Twenty-eight years ago, the first oil embargo was arude awakening to our vulnerability to energysupply disruptions. But that oil embargospurred Congress to create the Solar EnergyResearch Institute—designated a national lab-oratory and renamed the National Renewable

Energy Laboratory in 1991—to help develop thetechnology to make it possible to achieve a tran-

sition to a new energy future.

What has happened since SERI/NRELfirst began operating 25 years ago?

America uses nearly 50% more renewable energy than itdid then. We are witnessing the emergence of marketsbased on new energy technologies. America is employingenergy efficiency on a grander scale, decreasing its ener-gy intensity (energy used per dollar of gross domesticproduct) by about 1% per year.

Yet, today America is more dependent on foreign oil thanever. We use more natural gas and 75% more coal thanwe did in 1977. Driven largely by economic growth, ourenergy consumption has jumped by about 23 quads(where one quad equals 1015 Btus), with less than 3quads of that increase coming from renewable energy.This has resulted in large increases in greenhouse gasemissions and in air pollutants.

In light of these facts, is it still possible to achieve sus-tainable energy use? Yes—in the long run. We must re-member that it took 50 years from the building of the firstoil refinery until oil provided 10% of America’s energymix, and 60 years for natural gas to do likewise.

In the short term, with a portfolio of new energy tech-nologies and an enlightened public policy, we will pro-duce incremental changes. But these changes will,working with the existing energy infrastructure, begin tobuild exponentially to become significant in two, three,or four decades. And in the long term, what started assmall changes will grow to become a paradigm shift inhow America uses energy.

At the heart of this shift will be technology. And at theheart of the technology will be NREL. For the past 25years, NREL has helped build a foundation of renewableenergy and energy efficiency science and technology toput sustainable energy use within reach. For the next 25years and more, NREL will remain at the technology fore-front to spur various transitions toward sustainable ener-gy. This silver anniversary first biennial 2002 ResearchReview lays out a series of key transitions that will allow

us to move toward a sustainable world and indi-cates ways in which NREL and its partners aremaking that possible.

Wind and solar electricity markets, for example,are growing at rates greater than 30% per year.With help from advances such as NREL’s ad-vanced airfoil designs, wind power is alreadynearly competitive with some fossil-fuel main-

grid electricity generation. With potential inthe Great Plains alone to generate all ofAmerica’s electrical needs, wind power couldsoon become a major energy contributor, es-pecially as we develop the technology thatenables wind turbines to produce competitiveelectricity in low-wind-speed regimes.

As the solid-state approach to converting solarenergy to electricity, photovoltaic (PV) solarcells are the epitome of “futuristic” energy andare the best choice for high-tech applicationssuch as communications satellites and spaceshuttles. They also are becoming a preferredchoice for remote applications, for distributedgeneration, and for applications in which PVcan be integrated directly into the façade orstructure of buildings. NREL’s research on in-novative concepts that could help drop costssignificantly also could make solar electricitya preferred choice for main-grid power in an-other couple of decades.

But the future could easily bring a moveaway from reliance on main-grid power oreven electricity as the only energy carrier.New modular technologies (small gas tur-bines, fuel cells, solar cells, wind turbines,bioelectricity) and market needs—such ashigh-quality power for high-tech compa-nies—have created opportunities for electri-cal generation at the user site. In the sectionon distributed energy resources, we explainhow NREL works on improving the institu-tional as well as the technological ability tointegrate these distributed energy resourceswith the electrical generation system.

Hydrogen, like electricity, is easy to transportand burns cleanly, so makes a great energy car-rier. And because hydrogen can be producedand used as part of a clean, cyclic processwhen generated with a renewable source, itrepresents one of our most promising paths to-ward a sustainable energy future. In the sectionon the hydrogen economy, we describe severaltechnologies that NREL researchers are explor-ing to cleanly and efficiently produce hydrogenwith renewable energy.

When it comes to reducing vulnerabilityto dependence on foreign oil, it is vitallyimportant to develop alternative trans-portation fuels. NREL leads efforts to de-

velop technology to produce fuel ethanolfrom lignocellulosic biomass—the bulk of

most plant materials. In the section on biore-fineries, we describe how this technology andfive other core biomass technologies can beused not only to produce fuel but also to makeplastics, fibers, and other products now de-rived from chemicals produced at oil refineriesfrom petroleum. These six biomass technolo-gies are the platforms from which we canbuild the biomass economy and the biorefin-ery concept into a significant presence.

Hand-in-hand with research on fuels andproducts from biorefineries goes NREL’s re-search on transportation technologies. This in-cludes research to make transportationvehicles cleaner and more efficient, from“cool cars” that save on air-conditioning, toclean diesel engines and designer fuels, to ve-hicles that run on alternative fuels, to hybridelectric vehicles. All of which will help re-duce demand for foreign oil.

And last but not least, as with money, thebest way to make energy is to save energy. Inthe section on energy-efficient buildings, wedescribe a whole-building design approach,and a variety of technologies such as solarheating, natural daylighting, and building-integrated photovoltaics that NREL is de-veloping to reduce energy use in homesand commercial buildings. Efficient designand modern technology will enable us to de-velop zero-energy buildings—where abuilding’s energy use will be reduced tozero—an attainable goalfor homes built duringthe next 25 years.

Each of these energytransitions will be impor-tant in its own right andwill contribute toAmerica’s economy andto its path toward greaterenergy security. But tak-en together, they repre-sent a formidable forcethat could pave the wayto a new energy para-digm and a truly sustain-able energy future.

i 1

The 2002 Research ReviewThis Silver Anniversary 2002 Research Review is intendedas the first in a series of biennial overview reports on re-search progress at NREL. These reports will become part ofa series of semiannual journals, with the regular journal is-sues exploring particular NREL research efforts in depth.

In This Issue

Twenty-eight years ago, the first oil embargo was arude awakening to our vulnerability to energysupply disruptions. But that oil embargospurred Congress to create the Solar EnergyResearch Institute—designated a national lab-oratory and renamed the National Renewable

Energy Laboratory in 1991—to help develop thetechnology to make it possible to achieve a tran-

sition to a new energy future.

What has happened since SERI/NRELfirst began operating 25 years ago?

America uses nearly 50% more renewable energy than itdid then. We are witnessing the emergence of marketsbased on new energy technologies. America is employingenergy efficiency on a grander scale, decreasing its ener-gy intensity (energy used per dollar of gross domesticproduct) by about 1% per year.

Yet, today America is more dependent on foreign oil thanever. We use more natural gas and 75% more coal thanwe did in 1977. Driven largely by economic growth, ourenergy consumption has jumped by about 23 quads(where one quad equals 1015 Btus), with less than 3quads of that increase coming from renewable energy.This has resulted in large increases in greenhouse gasemissions and in air pollutants.

In light of these facts, is it still possible to achieve sus-tainable energy use? Yes—in the long run. We must re-member that it took 50 years from the building of the firstoil refinery until oil provided 10% of America’s energymix, and 60 years for natural gas to do likewise.

In the short term, with a portfolio of new energy tech-nologies and an enlightened public policy, we will pro-duce incremental changes. But these changes will,working with the existing energy infrastructure, begin tobuild exponentially to become significant in two, three,or four decades. And in the long term, what started assmall changes will grow to become a paradigm shift inhow America uses energy.

At the heart of this shift will be technology. And at theheart of the technology will be NREL. For the past 25years, NREL has helped build a foundation of renewableenergy and energy efficiency science and technology toput sustainable energy use within reach. For the next 25years and more, NREL will remain at the technology fore-front to spur various transitions toward sustainable ener-gy. This silver anniversary first biennial 2002 ResearchReview lays out a series of key transitions that will allow

us to move toward a sustainable world and indi-cates ways in which NREL and its partners aremaking that possible.

Wind and solar electricity markets, for example,are growing at rates greater than 30% per year.With help from advances such as NREL’s ad-vanced airfoil designs, wind power is alreadynearly competitive with some fossil-fuel main-

grid electricity generation. With potential inthe Great Plains alone to generate all ofAmerica’s electrical needs, wind power couldsoon become a major energy contributor, es-pecially as we develop the technology thatenables wind turbines to produce competitiveelectricity in low-wind-speed regimes.

As the solid-state approach to converting solarenergy to electricity, photovoltaic (PV) solarcells are the epitome of “futuristic” energy andare the best choice for high-tech applicationssuch as communications satellites and spaceshuttles. They also are becoming a preferredchoice for remote applications, for distributedgeneration, and for applications in which PVcan be integrated directly into the façade orstructure of buildings. NREL’s research on in-novative concepts that could help drop costssignificantly also could make solar electricitya preferred choice for main-grid power in an-other couple of decades.

But the future could easily bring a moveaway from reliance on main-grid power oreven electricity as the only energy carrier.New modular technologies (small gas tur-bines, fuel cells, solar cells, wind turbines,bioelectricity) and market needs—such ashigh-quality power for high-tech compa-nies—have created opportunities for electri-cal generation at the user site. In the sectionon distributed energy resources, we explainhow NREL works on improving the institu-tional as well as the technological ability tointegrate these distributed energy resourceswith the electrical generation system.

Hydrogen, like electricity, is easy to transportand burns cleanly, so makes a great energy car-rier. And because hydrogen can be producedand used as part of a clean, cyclic processwhen generated with a renewable source, itrepresents one of our most promising paths to-ward a sustainable energy future. In the sectionon the hydrogen economy, we describe severaltechnologies that NREL researchers are explor-ing to cleanly and efficiently produce hydrogenwith renewable energy.

When it comes to reducing vulnerabilityto dependence on foreign oil, it is vitallyimportant to develop alternative trans-portation fuels. NREL leads efforts to de-

velop technology to produce fuel ethanolfrom lignocellulosic biomass—the bulk of

most plant materials. In the section on biore-fineries, we describe how this technology andfive other core biomass technologies can beused not only to produce fuel but also to makeplastics, fibers, and other products now de-rived from chemicals produced at oil refineriesfrom petroleum. These six biomass technolo-gies are the platforms from which we canbuild the biomass economy and the biorefin-ery concept into a significant presence.

Hand-in-hand with research on fuels andproducts from biorefineries goes NREL’s re-search on transportation technologies. This in-cludes research to make transportationvehicles cleaner and more efficient, from“cool cars” that save on air-conditioning, toclean diesel engines and designer fuels, to ve-hicles that run on alternative fuels, to hybridelectric vehicles. All of which will help re-duce demand for foreign oil.

And last but not least, as with money, thebest way to make energy is to save energy. Inthe section on energy-efficient buildings, wedescribe a whole-building design approach,and a variety of technologies such as solarheating, natural daylighting, and building-integrated photovoltaics that NREL is de-veloping to reduce energy use in homesand commercial buildings. Efficient designand modern technology will enable us to de-velop zero-energy buildings—where abuilding’s energy use will be reduced tozero—an attainable goalfor homes built duringthe next 25 years.

Each of these energytransitions will be impor-tant in its own right andwill contribute toAmerica’s economy andto its path toward greaterenergy security. But tak-en together, they repre-sent a formidable forcethat could pave the wayto a new energy para-digm and a truly sustain-able energy future.

Biorefineries . . . . . . . . . . . . . . . . . . . 2

Transportation Technologies. . . . . . . . 6

Hydrogen Economy . . . . . . . . . . . . . 10

Solar Electricity . . . . . . . . . . . . . . . . 14

Distributed Energy Resources . . . . . 18

Energy-Efficient Buildings . . . . . . . . 22

Low-Wind-Speed Turbines . . . . . . . . 26

Epilogue . . . . . . . . . . . . . . . . . . . . . 28

1

The 2002 Research ReviewThis Silver Anniversary 2002 Research Review is intendedas the first in a series of biennial overview reports on re-search progress at NREL. These reports will become part ofa series of semiannual journals, with the regular journal is-sues exploring particular NREL research efforts in depth.

In This Issue

The 20th century was the century of thepetrochemical economy. Gasoline anddiesel (made from petroleum) power al-

most all our vehicles.Myriad plastics made from

petroleum or natural gas areused to make our clothes,

carpets, food packaging, andincreasingly, our car parts and building materials.Most of our chemicals and even toiletries andpharmaceuticals are petrochemically derived.

Unfortunately for the UnitedStates, most of the world’s pe-troleum is located elsewhere,so we import more than half ofwhat we use, creating heavyeconomic and security bur-dens. And unfortunately for theworld, whenever gasoline,diesel, and other fossil fuels areburned, they release carbondioxide that had been lockedup underground for millions ofyears, increasing greenhousegas levels.

In the 21st century, use of bio-mass—plants and plant-basedmaterials, produced by photo-synthesis within biologicalrather than geologic time—willoffset this petrochemical de-pendence. Biomass can’t fully

replace the huge volumes ofpetroleum and other fos-

sil fuels that we nowuse, but it can

provide fuels and chemicals comparable tothose derived from petroleum. Americanfarmers and foresters can fuel as well as feedand house America—in a sustainable fashion.

During the past 25 years, NREL researchershave developed an impressive slate of corebiological, physical, chemical, and engineer-ing skills for biomass technologies. With pri-mary responsibility for carrying out U.S.Department of Energy Biomass Programs,NREL’s National Bioenergy Center is at theforefront of efforts to develop the biologicaland thermochemical technologies that will al-low economically and environmentally re-sponsible production of fuels, chemicals, andpower from biomass to meet modern-dayneeds—the biomass economy.

Six Biomass Platforms

In 2000 and 2001, biomass, largely because ofbiomass power—combustion of materials suchas timber industry scrap or municipal solidwaste to generate electricity—surpassed hy-droelectric power as the largest U.S. source ofrenewable energy. And in 2002, U.S. produc-tion of fuel ethanol, made from corn grain(starch), will surpass 2 billion gallons per year,displacing a modest but significant amount ofimported oil. Also in 2002, a collaborativeventure of two major companies began pro-duction of polylactic acid plastic made frombiomass for clothing and packaging.

NREL researchers, who have made importantcontributions to each of these developments,are working to improve and greatly expandthese technologies through six different core

technologies or “platforms” for building thebiomass economy. Just as oil refineries breakdown petroleum and natural gas into numer-ous materials that then serve as commodity orplatform chemicals that the petrochemical in-dustry can use to make a multitude of finalproducts, these six biomass technology plat-forms will provide the base chemicals formaking biobased fuels and products.

The Sugar-Lignin Platform. One out of eightgallons of gasoline sold in the United Statesalready includes ethanol as an additive.Ethanol is made by fermenting sugar, most ofwhich is derived from starch in corn kernels.In contrast, instead of starting with sugar,NREL’s advanced bioethanol technology startswith cellulose and hemicellulose, two of thethree main components of most plant material—vastly expanding potential feedstocks—break-ing them down to sugars for fermentation. Inaddition to ethanol, the sugars, or intermedi-ate breakdown products, can be fermented,polymerized, or otherwise processed into anynumber of products. Lignin, the third maincomponent of biomass, can fuel the processor be used to produce a slate of differentchemicals, expanding the number of productsfor the sugar-lignin platform biorefinery. (Seesidebar “Lignocellulosic Bioethanol.”)

The Syngas Platform. If biomass is heatedwith limited oxygen (about one-third thatneeded for ideal combustion), it gasifies to a“syngas” composed mostly of hydrogen andcarbon monoxide. That syngas inherentlyburns cleaner and more efficiently than the

Biomass Characterization Technology

One reason NREL is so effective inbiomass technology research anddevelopment is because of its capa-bilities to analyze biomass and inter-mediates from its processing.Biomass gasification and pyrolysisboth require precise characteriza-tion of the breakdown products be-ing generated, so that processes canbe fine-tuned to produce optimalend products.

NREL uses sophisticated molecularbeam mass spectrometry and hasdeveloped a portable system thatcould have great value for syngasand bio-oil platform industries.

NREL’s R&D 100 Award-winningRapid Biomass Analysis systemquickly and inexpensively character-izes chemical and mechanical prop-erties of raw or processed biomass.Using near-infrared spectrometry cor-related by multivariate analysis, itcharacterizes in minutes what wouldotherwise require three or four daysand cost far more. Opportunities foruse in the lumber and paper indus-tries, let alone biorefineries, are al-most limitless. NREL researchers arecurrently using this approach to ana-lyze variations in corn stover compo-sition and their implications forethanol production.

Switchgrass, which can beeasily grown throughout muchof the United States, repre-sents a huge future resourceof lignocellulosic biomass foruse in biorefineries.

uing research of the basic biochemistry underlying biorefineryprocesses are key to major technology advances.

Artistic rendition of a cellulase enzyme breaking cellulosedown to component sugars. NREL’s understanding and contin-

Current ethanol production isprimarily from the starch in

kernels of field corn. NREL re-searchers are developing

technology to also produceethanol from the fibrous ma-terial (cellulose and hemicel-lulose) in the corn husks andstalks or in other agricultural

or forestry residues.

2 3

NREL has world-class facilitiesfor testing technologies thatwould be used for biorefiner-ies. These facilities are avail-able to NREL researchers aswell as to NREL’s researchpartners, under a variety ofagreements.

On the biological side, NRELhas a one-ton-per-day-feed-stock bioethanol pilot plantthat can take cellulosic bio-mass all the way from feed-stock preparation throughpretreatment, hydrolysis, andfermentation to distillation offuel ethanol. The plant is certi-fied to handle metabolicallyengineered fermentation or-ganisms such as NREL’sZymomonas mobilis, can useany of several pretreatment op-

tions, and includes completeprocess monitoring.

On the thermochemical side,the Thermochemical UsersFacility simulates thermochemi-cal processes such as gasifica-tion, combustion, and pyrolysis.The facility includes cyclonicand fluidized bed reactors forpyrolysis or gasification andcan easily accommodate re-search partners’ reactors. A va-riety of secondary reactor andcondensation equipment isavailable, and conversionproducts can be analyzed on-line with molecular beammass spectrometry, fouriertransform infrared spectrome-try, infrared spectrometry, orgas chromatography.

Biomass Conversion Facilities

The 20th century was the century of thepetrochemical economy. Gasoline anddiesel (made from petroleum) power al-

most all our vehicles.Myriad plastics made from

petroleum or natural gas areused to make our clothes,

carpets, food packaging, andincreasingly, our car parts and building materials.Most of our chemicals and even toiletries andpharmaceuticals are petrochemically derived.

Unfortunately for the UnitedStates, most of the world’s pe-troleum is located elsewhere,so we import more than half ofwhat we use, creating heavyeconomic and security bur-dens. And unfortunately for theworld, whenever gasoline,diesel, and other fossil fuels areburned, they release carbondioxide that had been lockedup underground for millions ofyears, increasing greenhousegas levels.

In the 21st century, use of bio-mass—plants and plant-basedmaterials, produced by photo-synthesis within biologicalrather than geologic time—willoffset this petrochemical de-pendence. Biomass can’t fully

replace the huge volumes ofpetroleum and other fos-

sil fuels that we nowuse, but it can

provide fuels and chemicals comparable tothose derived from petroleum. Americanfarmers and foresters can fuel as well as feedand house America—in a sustainable fashion.

During the past 25 years, NREL researchershave developed an impressive slate of corebiological, physical, chemical, and engineer-ing skills for biomass technologies. With pri-mary responsibility for carrying out U.S.Department of Energy Biomass Programs,NREL’s National Bioenergy Center is at theforefront of efforts to develop the biologicaland thermochemical technologies that will al-low economically and environmentally re-sponsible production of fuels, chemicals, andpower from biomass to meet modern-dayneeds—the biomass economy.

Six Biomass Platforms

In 2000 and 2001, biomass, largely because ofbiomass power—combustion of materials suchas timber industry scrap or municipal solidwaste to generate electricity—surpassed hy-droelectric power as the largest U.S. source ofrenewable energy. And in 2002, U.S. produc-tion of fuel ethanol, made from corn grain(starch), will surpass 2 billion gallons per year,displacing a modest but significant amount ofimported oil. Also in 2002, a collaborativeventure of two major companies began pro-duction of polylactic acid plastic made frombiomass for clothing and packaging.

NREL researchers, who have made importantcontributions to each of these developments,are working to improve and greatly expandthese technologies through six different core

technologies or “platforms” for building thebiomass economy. Just as oil refineries breakdown petroleum and natural gas into numer-ous materials that then serve as commodity orplatform chemicals that the petrochemical in-dustry can use to make a multitude of finalproducts, these six biomass technology plat-forms will provide the base chemicals formaking biobased fuels and products.

The Sugar-Lignin Platform. One out of eightgallons of gasoline sold in the United Statesalready includes ethanol as an additive.Ethanol is made by fermenting sugar, most ofwhich is derived from starch in corn kernels.In contrast, instead of starting with sugar,NREL’s advanced bioethanol technology startswith cellulose and hemicellulose, two of thethree main components of most plant material—vastly expanding potential feedstocks—break-ing them down to sugars for fermentation. Inaddition to ethanol, the sugars, or intermedi-ate breakdown products, can be fermented,polymerized, or otherwise processed into anynumber of products. Lignin, the third maincomponent of biomass, can fuel the processor be used to produce a slate of differentchemicals, expanding the number of productsfor the sugar-lignin platform biorefinery. (Seesidebar “Lignocellulosic Bioethanol.”)

The Syngas Platform. If biomass is heatedwith limited oxygen (about one-third thatneeded for ideal combustion), it gasifies to a“syngas” composed mostly of hydrogen andcarbon monoxide. That syngas inherentlyburns cleaner and more efficiently than the

Biomass Characterization Technology

One reason NREL is so effective inbiomass technology research anddevelopment is because of its capa-bilities to analyze biomass and inter-mediates from its processing.Biomass gasification and pyrolysisboth require precise characteriza-tion of the breakdown products be-ing generated, so that processes canbe fine-tuned to produce optimalend products.

NREL uses sophisticated molecularbeam mass spectrometry and hasdeveloped a portable system thatcould have great value for syngasand bio-oil platform industries.

NREL’s R&D 100 Award-winningRapid Biomass Analysis systemquickly and inexpensively character-izes chemical and mechanical prop-erties of raw or processed biomass.Using near-infrared spectrometry cor-related by multivariate analysis, itcharacterizes in minutes what wouldotherwise require three or four daysand cost far more. Opportunities foruse in the lumber and paper indus-tries, let alone biorefineries, are al-most limitless. NREL researchers arecurrently using this approach to ana-lyze variations in corn stover compo-sition and their implications forethanol production.

Switchgrass, which can beeasily grown throughout muchof the United States, repre-sents a huge future resourceof lignocellulosic biomass foruse in biorefineries.

uing research of the basic biochemistry underlying biorefineryprocesses are key to major technology advances.

Artistic rendition of a cellulase enzyme breaking cellulosedown to component sugars. NREL’s understanding and contin-

Current ethanol production isprimarily from the starch in

kernels of field corn. NREL re-searchers are developing

technology to also produceethanol from the fibrous ma-terial (cellulose and hemicel-lulose) in the corn husks andstalks or in other agricultural

or forestry residues.

3

NREL has world-class facilitiesfor testing technologies thatwould be used for biorefiner-ies. These facilities are avail-able to NREL researchers aswell as to NREL’s researchpartners, under a variety ofagreements.

On the biological side, NRELhas a one-ton-per-day-feed-stock bioethanol pilot plantthat can take cellulosic bio-mass all the way from feed-stock preparation throughpretreatment, hydrolysis, andfermentation to distillation offuel ethanol. The plant is certi-fied to handle metabolicallyengineered fermentation or-ganisms such as NREL’sZymomonas mobilis, can useany of several pretreatment op-

tions, and includes completeprocess monitoring.

On the thermochemical side,the Thermochemical UsersFacility simulates thermochemi-cal processes such as gasifica-tion, combustion, and pyrolysis.The facility includes cyclonicand fluidized bed reactors forpyrolysis or gasification andcan easily accommodate re-search partners’ reactors. A va-riety of secondary reactor andcondensation equipment isavailable, and conversionproducts can be analyzed on-line with molecular beammass spectrometry, fouriertransform infrared spectrome-try, infrared spectrometry, orgas chromatography.

Biomass Conversion Facilities

raw biomass. NREL scientists are using gasifi-cation technology to improve a large innova-tive biomass power plant in Vermont (seesidebar “Vermont Gasifier”) and to pro-vide electricity for the first time to isolat-ed Philippine villages with smallelectric generators. The syngas alsocan be used to produce hydrogen(see “Hydrogen Economy” on pages10-13) which, in turn, can be usedas a fuel or to make plastics, fertil-izers, and a wide variety of otherproducts. Syngas can also beconverted to sulfur-free liquidtransportation fuels using a cat-alytic process (known as theFischer-Tropsch Process), or pro-vide base chemicals for producingbiobased products.

The Bio-Oil Platform. If biomass is heated tohigh temperatures in the total absence of oxy-gen, it pyrolyzes to a liquid that is oxygenated,but otherwise has similar characteristics to pe-troleum. This pyrolysis- or “bio-” oil can beburned to generate electricity or it can be usedto provide base chemicals for biobased prod-ucts. As an example, NREL researchers haveextracted phenolics from bio-oil to make ad-hesives and plastic resins. NREL uses severalthermochemical reactor systems—available foruse by outside researchers—to efficiently py-rolyze and control the bio-oil components.NREL scientists have also used pyrolysis for“true recycling” of plastics such as nylon car-peting, selectively regenerating the base chem-icals from which the plastics were made.

The Biogas Platform. Another way to convert“waste” biomass into useful fuels and prod-

ucts is to have natural consortiums of anaer-obic microorganisms decompose the materialin closed systems. Anaerobic microorgan-isms break down or “digest” organic materialin the absence of oxygen and produce bio-gas as a waste product. Biogas produced inclosed tanks, or anaerobic digesters, consistsof 50% to 80% methane, 20% to 50% car-bon dioxide, and trace levels of other gasessuch as hydrogen, carbon monoxide, oxy-gen, and nitrogen. NREL has developed ananaerobic digestion system that handlesmuch higher solids loading than typical di-gesters. This system effectively converts cel-lulosic waste (such as municipal solid waste)and fatty waste (such as tuna cannerysludge) to a methane-rich biogas suitable forpower generation (or as a starting materialfor biobased products) and usable compostmaterial. Anaerobic digesters are currentlygetting considerable attention as a way toturn swine and cattle manure into useful fueland chemicals.

The Carbon-Rich Chains Platform. Plant andanimal fats and oils are long hydrocarbonchains, as are their fossil-fuel counterparts.Some are directly usable as fuels, but theycan also be modified to better meet currentneeds. Fatty acid methyl ester—fat or oil“transesterified” by combination withmethanol—substitutes directly for petroleumdiesel. Known as biodiesel, it differs primari-ly in containing oxygen, so it burns cleaner,

either by itself or as an additive. Biodieseluse is small but growing rapidly. In theUnited States, it is made mostly from soy-bean oil and used cooking oil. Soybeanmeal, the coproduct of oil extraction is nowused primarily as animal feed, but also couldbe a base for making biobased products.Glycerin, the coproduct of making biodiesel,is already used to make a variety of prod-ucts, but has potential for many more. Andthe fatty acids are used for detergents andother products. So carbon-rich chains arealready well on their way as a platform forthe biorefinery.

The Plant Products Platform. Modernbiotechnology not only can transform materi-als extracted from plants, but can transformthe plants to produce more valuable materi-als. Selective breeding and genetic engineer-ing can be used to improve production ofchemical, as well as food, fiber, and structur-al products. Plants can be developed to pro-duce high-value chemicals in greater quantitythan they do naturally, or even to producecompounds they do not naturally produce.With its genetic engineering, material andeconomic analysis, and general biotechnolo-gy expertise, NREL could make major contri-butions in this exciting arena. For example,NREL researchers exploring variation in com-position of stover for various strains of cornare analyzing the impact this makes on pro-ducing ethanol from stover.

Moving to Biorefineries

As exciting as these six platforms are, biore-fineries will not happen overnight. The oil re-fineries, and the corn wet-mills and pulp andpaper plants (the biorefineries of today) thatthey would parallel, are highly complex andvery expensive. No new U.S. oil refinerieshave been built in the past 30 years. Cornwet-mills produce a variety of food products—as well as ethanol—from starch, but mostnew ethanol plants are smaller dry mills pro-ducing just ethanol and animal feed. To over-

come the challenge and complexity ofproducing a slate of products starting withlignocellulosic material instead of oil orstarch will require enhanced technology de-velopment. NREL is providing the foundationfor this to occur.

Two important concepts are guiding NREL’sefforts to create novel, successful biorefiner-ies—taking maximum advantage of interme-diate products and balancing high-value/low-volume products with high-volume/low-valuefuels. High-value bioproducts may meet spe-cial needs and generate market excitement,but high-volume fuels are what Americaneeds to reduce its dependence on foreignoil and to improve the environment.

Biorefineries will not eliminate the need forpetrochemicals. But they will play a key rolein reducing our level of dependence on im-ported petroleum and making the 21st centuryone of an increasingly sustainable, domestic,and environmentally responsible biomasseconomy.

Vermont GasifierAt the McNeil Biomass Power GeneratingStation in Burlington, Vermont, NREL re-searchers helped design and install anR&D 100 Award-winning gasificationsystem. The project is one of two majorDOE projects to develop technology todramatically improve the efficiency andair emissions quality of biomass powersystems. The McNeil Station already issuccessfully burning up to 200 tons perday of gasified wood chips in its normalsteam generator. Once the gas is hookedup to a planned gas turbine, efficiencyshould be double that of a combustion-boiler generation system.

Lignocellulosic BioethanolNREL and the corn-starch-to-fuel-ethanol industry have grown uptogether during the past 25 years.NREL has contributed significant-ly to the industry maturing to oneutilizing energy-efficient tech-nologies.

NREL researchers are focusing onthe challenge of producingbioethanol from lignocellulosicbiomass instead of corn starch.Toward this end, NREL researchersalready have developed effectivetechnology to thermochemicallypretreat biomass; to hydrolyzehemicellulose to break it down in-to its component sugars and openup the cellulose to treatment; toenzymatically hydrolyze celluloseto break it down to sugars; and to

fermentboth five-carbon sugarsfrom hemicellu-lose and six-carbonsugars from cellulose. This entireprocess has been integrated usingan NREL-patented R&D 100Award-winning metabolically en-gineered bacteria—Zymomonasmobilis. Using a one-ton-feed-stock-per-day bioethanol pilotplant, NREL researchers are testingand improving these technologiesunder conditions that simulate in-dustrial production.

Bioethanol and the biorefineryconcept are closely linked. Thecellulosic ethanol technology de-veloped by NREL will open thedoor to making a wealth of otherproducts. Just as cellulose andhemicellulose are polymers ofsugars, new polymers can bemade from those sugars.Biodegradable plastics and natu-ral, nontoxic herbicides are justsome of the possibilities NREL re-searchers are exploring.

The Vermont gasifier, oneof the first large-scale

demonstrations of bio-mass gasification, sup-plies clean, renewable

fuel from biomass to theMcNeil Biomass Power

Generating Station inBurlington, Vermont.

NREL uses a one-ton-per-day pilot plant totest bioethanol tech-

nologies, includingNREL’s metabolicallyengineered bacteria,

Zymomonas mobilis,which enables the

cofermentation of cellu-lose and hemicellulose.

4 5

A researcher examines a beaker containing cellulase en-zymes, a key element in producing ethanol from lignocellu-losic biomass.

raw biomass. NREL scientists are using gasifi-cation technology to improve a large innova-tive biomass power plant in Vermont (seesidebar “Vermont Gasifier”) and to pro-vide electricity for the first time to isolat-ed Philippine villages with smallelectric generators. The syngas alsocan be used to produce hydrogen(see “Hydrogen Economy” on pages10-13) which, in turn, can be usedas a fuel or to make plastics, fertil-izers, and a wide variety of otherproducts. Syngas can also beconverted to sulfur-free liquidtransportation fuels using a cat-alytic process (known as theFischer-Tropsch Process), or pro-vide base chemicals for producingbiobased products.

The Bio-Oil Platform. If biomass is heated tohigh temperatures in the total absence of oxy-gen, it pyrolyzes to a liquid that is oxygenated,but otherwise has similar characteristics to pe-troleum. This pyrolysis- or “bio-” oil can beburned to generate electricity or it can be usedto provide base chemicals for biobased prod-ucts. As an example, NREL researchers haveextracted phenolics from bio-oil to make ad-hesives and plastic resins. NREL uses severalthermochemical reactor systems—available foruse by outside researchers—to efficiently py-rolyze and control the bio-oil components.NREL scientists have also used pyrolysis for“true recycling” of plastics such as nylon car-peting, selectively regenerating the base chem-icals from which the plastics were made.

The Biogas Platform. Another way to convert“waste” biomass into useful fuels and prod-

ucts is to have natural consortiums of anaer-obic microorganisms decompose the materialin closed systems. Anaerobic microorgan-isms break down or “digest” organic materialin the absence of oxygen and produce bio-gas as a waste product. Biogas produced inclosed tanks, or anaerobic digesters, consistsof 50% to 80% methane, 20% to 50% car-bon dioxide, and trace levels of other gasessuch as hydrogen, carbon monoxide, oxy-gen, and nitrogen. NREL has developed ananaerobic digestion system that handlesmuch higher solids loading than typical di-gesters. This system effectively converts cel-lulosic waste (such as municipal solid waste)and fatty waste (such as tuna cannerysludge) to a methane-rich biogas suitable forpower generation (or as a starting materialfor biobased products) and usable compostmaterial. Anaerobic digesters are currentlygetting considerable attention as a way toturn swine and cattle manure into useful fueland chemicals.

The Carbon-Rich Chains Platform. Plant andanimal fats and oils are long hydrocarbonchains, as are their fossil-fuel counterparts.Some are directly usable as fuels, but theycan also be modified to better meet currentneeds. Fatty acid methyl ester—fat or oil“transesterified” by combination withmethanol—substitutes directly for petroleumdiesel. Known as biodiesel, it differs primari-ly in containing oxygen, so it burns cleaner,

either by itself or as an additive. Biodieseluse is small but growing rapidly. In theUnited States, it is made mostly from soy-bean oil and used cooking oil. Soybeanmeal, the coproduct of oil extraction is nowused primarily as animal feed, but also couldbe a base for making biobased products.Glycerin, the coproduct of making biodiesel,is already used to make a variety of prod-ucts, but has potential for many more. Andthe fatty acids are used for detergents andother products. So carbon-rich chains arealready well on their way as a platform forthe biorefinery.

The Plant Products Platform. Modernbiotechnology not only can transform materi-als extracted from plants, but can transformthe plants to produce more valuable materi-als. Selective breeding and genetic engineer-ing can be used to improve production ofchemical, as well as food, fiber, and structur-al products. Plants can be developed to pro-duce high-value chemicals in greater quantitythan they do naturally, or even to producecompounds they do not naturally produce.With its genetic engineering, material andeconomic analysis, and general biotechnolo-gy expertise, NREL could make major contri-butions in this exciting arena. For example,NREL researchers exploring variation in com-position of stover for various strains of cornare analyzing the impact this makes on pro-ducing ethanol from stover.

Moving to Biorefineries

As exciting as these six platforms are, biore-fineries will not happen overnight. The oil re-fineries, and the corn wet-mills and pulp andpaper plants (the biorefineries of today) thatthey would parallel, are highly complex andvery expensive. No new U.S. oil refinerieshave been built in the past 30 years. Cornwet-mills produce a variety of food products—as well as ethanol—from starch, but mostnew ethanol plants are smaller dry mills pro-ducing just ethanol and animal feed. To over-

come the challenge and complexity ofproducing a slate of products starting withlignocellulosic material instead of oil orstarch will require enhanced technology de-velopment. NREL is providing the foundationfor this to occur.

Two important concepts are guiding NREL’sefforts to create novel, successful biorefiner-ies—taking maximum advantage of interme-diate products and balancing high-value/low-volume products with high-volume/low-valuefuels. High-value bioproducts may meet spe-cial needs and generate market excitement,but high-volume fuels are what Americaneeds to reduce its dependence on foreignoil and to improve the environment.

Biorefineries will not eliminate the need forpetrochemicals. But they will play a key rolein reducing our level of dependence on im-ported petroleum and making the 21st centuryone of an increasingly sustainable, domestic,and environmentally responsible biomasseconomy.

Vermont GasifierAt the McNeil Biomass Power GeneratingStation in Burlington, Vermont, NREL re-searchers helped design and install anR&D 100 Award-winning gasificationsystem. The project is one of two majorDOE projects to develop technology todramatically improve the efficiency andair emissions quality of biomass powersystems. The McNeil Station already issuccessfully burning up to 200 tons perday of gasified wood chips in its normalsteam generator. Once the gas is hookedup to a planned gas turbine, efficiencyshould be double that of a combustion-boiler generation system.

Lignocellulosic BioethanolNREL and the corn-starch-to-fuel-ethanol industry have grown uptogether during the past 25 years.NREL has contributed significant-ly to the industry maturing to oneutilizing energy-efficient tech-nologies.

NREL researchers are focusing onthe challenge of producingbioethanol from lignocellulosicbiomass instead of corn starch.Toward this end, NREL researchersalready have developed effectivetechnology to thermochemicallypretreat biomass; to hydrolyzehemicellulose to break it down in-to its component sugars and openup the cellulose to treatment; toenzymatically hydrolyze celluloseto break it down to sugars; and to

fermentboth five-carbon sugarsfrom hemicellu-lose and six-carbonsugars from cellulose. This entireprocess has been integrated usingan NREL-patented R&D 100Award-winning metabolically en-gineered bacteria—Zymomonasmobilis. Using a one-ton-feed-stock-per-day bioethanol pilotplant, NREL researchers are testingand improving these technologiesunder conditions that simulate in-dustrial production.

Bioethanol and the biorefineryconcept are closely linked. Thecellulosic ethanol technology de-veloped by NREL will open thedoor to making a wealth of otherproducts. Just as cellulose andhemicellulose are polymers ofsugars, new polymers can bemade from those sugars.Biodegradable plastics and natu-ral, nontoxic herbicides are justsome of the possibilities NREL re-searchers are exploring.

The Vermont gasifier, oneof the first large-scale

demonstrations of bio-mass gasification, sup-plies clean, renewable

fuel from biomass to theMcNeil Biomass Power

Generating Station inBurlington, Vermont.

NREL uses a one-ton-per-day pilot plant totest bioethanol tech-

nologies, includingNREL’s metabolicallyengineered bacteria,

Zymomonas mobilis,which enables the

cofermentation of cellu-lose and hemicellulose.

5

A researcher examines a beaker containing cellulase en-zymes, a key element in producing ethanol from lignocellu-losic biomass.

Imagine a future in which you drive home from work, plug your car intoyour house, and have it provide electricity for evening lights and mealsand even supply electricity to the grid for the community’s benefit. Then,

in the lull of the night, your house or the grid willreturn the favor to produce for your car the energyit will need for the next day.

This is a technically possible future because your carcould well be a fuel-cell car that us-es hydrogen to produce electricity(see “Hydrogen Economy” on pages10-13). Your car could become a

distributed generator and your house a producer ofenergy and a refueling station. Concurrently, theemissions resulting from the use of energy for yourhouse and car can approach zero, if the hydrogenand the electricity are produced using renewable

energy resources and technologies.

For America’s transportation sector, striv-ing toward such a future is vitally impor-tant. Our transportation is almost entirelydependent on oil, nearly 60% of whicharrives in tankers from foreign shores.And our use of petroleum in transporta-tion translates directly into huge emis-sions of pollutants and greenhouse gases.

It is against this backdrop that Secretaryof Energy Spencer Abraham announcedthe FreedomCAR program, for researchinto “advanced, fuel-cell technology,which uses hydrogen to power automo-biles without creating pollution. The

long-term results ofthis…effort will be carsand trucks that aremore efficient, cheaperto operate, pollutionfree, and competitive.”

6

Multifaceted R&D Effort

Although the program and its emphasis are new,the long-term goals are familiar—greater energyindependence, reducing emissions, and buildinga hydrogen-supply infrastructure. They are onesthat NREL has been supporting for years underDOE guidance.

Achieving these goals requires a multitiered ap-proach and will involve many players—autoand component manufacturers, the energy in-dustry, government agencies, and national labo-ratories. For its part, NREL is helping the nationrealize these goals through two general path-ways: the development of advanced vehicles,systems, and components; and the testing anddevelopment of alternative fuels.

The Advanced Vehicle Pathway

A drawback of our current transportation sys-tem is that it relies heavily on internal com-bustion engines, which are quiteinefficient—the typical gasoline internal com-bustion engine for cars converts less than 18%of the heat energy in gasoline into kinetic en-ergy for the car. An alternative is the electricvehicle, whose efficiency can be greater than60% and whose operation does not generateemissions. However, the most popular choicefor powering electric vehicles—batteries—pro-vides only a short driving range. But by com-bining internal combustion with electricpropulsion, you get the best of both worlds: ahybrid electric vehicle (HEV) with a very gooddriving range, significantly increased efficien-

cy over the internal combustion engine, andgreatly reduced emissions.

You also get a pathway to the future fuel-cell ve-hicle—where fuels cells will eventually replacethe engine in a hybrid electric vehicle. Towardthis future, NREL emphasizes a systems ap-proach, in which we analyze subsystems andcomponents to determine how they may best beintegrated to optimize vehicle performance. Todo this, we develop interactive modeling toolsand make them available to others so that theymay more quickly optimize their designs ofcomponents and HEV systems (see sidebar“Accelerating Clean Vehicle Development”).

One of the subsystems we analyze is the batterypack and its thermal management. Different batter-ies tend to operate best at particular temperatureranges, which can change with the cycling of the

All major manufacturers are developinghybrid electric vehicles and fuel-cell vehi-cles that will produce far fewer emissions

and get greater mileage. Above is aHonda Insight hybrid electric car and aGM S10 pickup truck that uses an on-

board reformer to produce hydrogen foruse in a fuel cell.

Car manufacturers are developingadvanced vehicles that will use lessfossil fuel and run cleaner. NRELcreated ADVISOR (ADvancedVehicle SimulatOR) to help acceler-ate that development. ADVISOR isan analysis software package thatprovides fast and accurate simula-tions of vehicle configurations withan emphasis on advanced power-trains and on optimizing designs forfuel efficiency and reduced emis-sions. It allows engineers to simulatenearly endless design options, re-ducing the time and the expense forbuilding and testing prototypes.

Easy to use, flexible, and robust,ADVISOR uses three primarygraphical interface screens toguide the user through the sim-ulation process. With the

Vehicle Input screen, the userchooses a predefined vehicle to

test, or creates a new vehicle froman extensive data base of vehiclecomponents and configurations. TheSimulation Setup screen allows theuser to test that vehicle under an in-credible range of simulated test pro-cedures, driving cycles, and loads.Finally, with the Results screen, theuser can view second-to-second re-sults from 127 output variables. This

is an iterative process that enablesthe designer to vary the parametersand optimize vehicle characteristics.

ADVISOR is primarily used to quan-tify the fuel economy, performance,and emissions of vehicles that useadvanced technologies such as fuelcells, batteries, and electric motorsfor hybrid electric vehicles, as wellas conventional technologies suchas internal combustion engines.

ADVISOR has attracted a rapidlygrowing worldwide community ofusers who incorporate it into theirown software programs. Users in-clude automotive manufacturersand suppliers, universities for re-search and training of engineers,research laboratories, and govern-ment organizations.

Accelerating CleanVehicle Development

Areas of the country that have air-qualityproblems will soon require the introduc-tion of ultra-low-emission vehicles into thetransportation mix. One strategy to meetthe emissions requirements is with hybridelectric vehicles. By 2010, there may be asmany as 250,000 HEVs sold in America.

HEVs often use nickel metal-hydride(NiMH) batteries because they havegreater energy density and last longerthan the more familiar, less expensivelead-acid batteries.

But things may be about to change,thanks to an R&D 100 Award-winningtechnology developed by NREL,Recombination Technologies, and OptimaBatteries. Lead-acid batteries have tradi-tionally been charged at a constant cur-rent and voltage. This constant-chargestrategy does not sufficiently recharge thenegative plate in the battery, and leads toa premature end of battery life.

NREL and its partners devised a clever,inexpensive technique—a current-inter-rupt charging algorithm—for charging thebatteries properly. The technique in-volves overcharging the battery for5 seconds then allowing it to rest for5 seconds. The rest period permits thebattery to cool and prevents it from go-ing into a gassing cycle.

This algorithm, which increases batterylife by three- to four-fold, enables lead-acid batteries to be competitive withNiMH batteries in terms of life cycle.

Going Farther for Less

The typical hybridelectric vehicle uses batter-

ies, an internal combustion engine,and a motor/generator for propulsion.

Such a hybrid configuration not onlygreatly extends gas mileage and cuts emis-sions, but may also serve as a precursor to

a fuel-cell vehicle.

InternalCombustion

Engine

Energy Mgmt &Control System

Battery Pack Fuel Tank

Motor/Generator

Thermal in-frared imageof lead-acidbattery during5-amp over-charge showstemperaturevariation of26°C to 33°C.

NREL’s ADVISOR software analysis packageuses interactive simulation to allow the userto interactively control the vehicle and toview vehicle and component response dur-ing the simulation.

7

Multifaceted R&D Effort

Although the program and its emphasis are new,the long-term goals are familiar—greater energyindependence, reducing emissions, and buildinga hydrogen-supply infrastructure. They are onesthat NREL has been supporting for years underDOE guidance.

Achieving these goals requires a multitiered ap-proach and will involve many players—autoand component manufacturers, the energy in-dustry, government agencies, and national labo-ratories. For its part, NREL is helping the nationrealize these goals through two general path-ways: the development of advanced vehicles,systems, and components; and the testing anddevelopment of alternative fuels.

The Advanced Vehicle Pathway

A drawback of our current transportation sys-tem is that it relies heavily on internal com-bustion engines, which are quiteinefficient—the typical gasoline internal com-bustion engine for cars converts less than 18%of the heat energy in gasoline into kinetic en-ergy for the car. An alternative is the electricvehicle, whose efficiency can be greater than60% and whose operation does not generateemissions. However, the most popular choicefor powering electric vehicles—batteries—pro-vides only a short driving range. But by com-bining internal combustion with electricpropulsion, you get the best of both worlds: ahybrid electric vehicle (HEV) with a very gooddriving range, significantly increased efficien-

cy over the internal combustion engine, andgreatly reduced emissions.

You also get a pathway to the future fuel-cell ve-hicle—where fuels cells will eventually replacethe engine in a hybrid electric vehicle. Towardthis future, NREL emphasizes a systems ap-proach, in which we analyze subsystems andcomponents to determine how they may best beintegrated to optimize vehicle performance. Todo this, we develop interactive modeling toolsand make them available to others so that theymay more quickly optimize their designs ofcomponents and HEV systems (see sidebar“Accelerating Clean Vehicle Development”).

One of the subsystems we analyze is the batterypack and its thermal management. Different batter-ies tend to operate best at particular temperatureranges, which can change with the cycling of the

All major manufacturers are developinghybrid electric vehicles and fuel-cell vehi-cles that will produce far fewer emissions

and get greater mileage. Above is aHonda Insight hybrid electric car and aGM S10 pickup truck that uses an on-

board reformer to produce hydrogen foruse in a fuel cell.

Car manufacturers are developingadvanced vehicles that will use lessfossil fuel and run cleaner. NRELcreated ADVISOR (ADvancedVehicle SimulatOR) to help acceler-ate that development. ADVISOR isan analysis software package thatprovides fast and accurate simula-tions of vehicle configurations withan emphasis on advanced power-trains and on optimizing designs forfuel efficiency and reduced emis-sions. It allows engineers to simulatenearly endless design options, re-ducing the time and the expense forbuilding and testing prototypes.

Easy to use, flexible, and robust,ADVISOR uses three primarygraphical interface screens toguide the user through the sim-ulation process. With the

Vehicle Input screen, the userchooses a predefined vehicle to

test, or creates a new vehicle froman extensive data base of vehiclecomponents and configurations. TheSimulation Setup screen allows theuser to test that vehicle under an in-credible range of simulated test pro-cedures, driving cycles, and loads.Finally, with the Results screen, theuser can view second-to-second re-sults from 127 output variables. This

is an iterative process that enablesthe designer to vary the parametersand optimize vehicle characteristics.

ADVISOR is primarily used to quan-tify the fuel economy, performance,and emissions of vehicles that useadvanced technologies such as fuelcells, batteries, and electric motorsfor hybrid electric vehicles, as wellas conventional technologies suchas internal combustion engines.

ADVISOR has attracted a rapidlygrowing worldwide community ofusers who incorporate it into theirown software programs. Users in-clude automotive manufacturersand suppliers, universities for re-search and training of engineers,research laboratories, and govern-ment organizations.

Accelerating CleanVehicle Development

Areas of the country that have air-qualityproblems will soon require the introduc-tion of ultra-low-emission vehicles into thetransportation mix. One strategy to meetthe emissions requirements is with hybridelectric vehicles. By 2010, there may be asmany as 250,000 HEVs sold in America.

HEVs often use nickel metal-hydride(NiMH) batteries because they havegreater energy density and last longerthan the more familiar, less expensivelead-acid batteries.

But things may be about to change,thanks to an R&D 100 Award-winningtechnology developed by NREL,Recombination Technologies, and OptimaBatteries. Lead-acid batteries have tradi-tionally been charged at a constant cur-rent and voltage. This constant-chargestrategy does not sufficiently recharge thenegative plate in the battery, and leads toa premature end of battery life.

NREL and its partners devised a clever,inexpensive technique—a current-inter-rupt charging algorithm—for charging thebatteries properly. The technique in-volves overcharging the battery for5 seconds then allowing it to rest for5 seconds. The rest period permits thebattery to cool and prevents it from go-ing into a gassing cycle.

This algorithm, which increases batterylife by three- to four-fold, enables lead-acid batteries to be competitive withNiMH batteries in terms of life cycle.

Going Farther for Less

The typical hybridelectric vehicle uses batter-

ies, an internal combustion engine,and a motor/generator for propulsion.

Such a hybrid configuration not onlygreatly extends gas mileage and cuts emis-sions, but may also serve as a precursor to

a fuel-cell vehicle.

InternalCombustion

Engine

Energy Mgmt &Control System

Battery Pack Fuel Tank

Motor/Generator

Thermal in-frared imageof lead-acidbattery during5-amp over-charge showstemperaturevariation of26°C to 33°C.

NREL’s ADVISOR software analysis packageuses interactive simulation to allow the userto interactively control the vehicle and toview vehicle and component response dur-ing the simulation.

The Fuel Pathway

A hydrogen infrastructure in which the hydro-gen fuel-cell car plays a starring role may bethe ideal to which to aspire, but there aremany options available that would enable thenation to cut its use of petroleum and in theprocess reduce its emissions. Among these op-tions are alternative fuels—including com-pressed natural gas, liquefied natural gas,ethanol, and methanol—that we can use in ourcars, trucks, and buses.

The first step in understanding how best to cutemissions and curtail oil consumption with al-ternative fuels is to establish a base that enablesus to make comparisons, to measure progress,and to understand the properties of fuels and theconsequences of its use. NREL is establishingsuch a base with a testing program it managesfor the Department of Energy—the AlternativeFuels Data Center. We test and analyze a widevariety of cars, trucks, vans, buses, and fleetsthat use alternative fuels. This program has en-abled us to build an extensive database on alter-native fuels, their properties, and theirperformance characteristics. The informationfrom this database is avail-able to anyone who wantsthe data, and it is used byfleet managers, munici-palities, manufacturers ofvehicles and components,the fuel industry, and re-searchers.

The next step is to devel-op alternative fuels, espe-cially ones that arederived from re-newable re-sources, such asbiomass. NREL

8 9

battery. Temperature variations from module tomodule can affect performance and life. Ouranalysis can point to ways in which to manage thetemperature of the battery subsystems, for best per-formance (see sidebar “Going Farther for Less”).

Other important subsystems are those that helpdetermine the comfort of the passenger—heat-ing, ventilation, cooling, and keeping the airclean. These auxiliary systems can consume alarge amount of energy. NREL uses an optimiza-tion approach to analyze auxiliary loads, simul-taneously modeling passenger comfort, heatingand air-conditioning, and vehicle performanceto determine how best to keep passengers com-fortable while minimizing fuel use and emis-sions. This systems approach, which canminimize auxiliary loads while increasing vehi-cle performance and passenger comfort, couldsave the nation billions of gallons of gasolineper year—to painlessly reduce our dependenceon foreign oil and enhance air quality.

develops these fuels through its biofuels andbiomass programs (see “Biorefineries” on pages2-5). These fuels are most often blended withgasoline—a strategy that not only gets more al-ternative fuels into the energy infrastructure, butalso helps curtail emissions.

A third step is to produce hydrogen from renew-able resources for use as both a fuel and an en-ergy carrier. This will dovetail nicely with theparallel development of fuel-cell vehicles. NRELpursues this alternative through its research inbasic energy sciences and through the DOE’shydrogen program (see “Hydrogen Economy”on pages 10-13).

The Heavy-duty Option. Another option for re-ducing emissions is to develop clean diesel fuelsfor heavy-duty vehicles. Diesel fuel accounts foralmost 20% of the fuel used on our highways,and its use in on-road heavy-duty vehicles gen-erates thousands of tons of nitrogen oxides, par-ticulate matter, and other pollutants each year.Working with industry, NREL has helped devel-op technologies and approaches in which dieselemissions can be drastically cut.

One approach byNREL and itspartners is todevelop clean“conventional”

diesel fuels for use with catalyzed filters (seesidebar “Breathing Easier”). A second approachis to develop clean synthetic fuels from naturalgas (or synthesis gas—primarily hydrogen andcarbon monoxide) in conjunction with modify-ing a diesel engine to optimally burn the syn-thetic diesel. With this approach, carbonmonoxide emissions can be nearly eliminated,while particulate matter and nitrogen oxidescan be reduced by up to 97%.

Designer Fuels. A further strategy is to designdiesel fuels on the molecular level. In this way,you can design for particular properties of a fu-el—such as the cetane number (a measure ofhow readily the fuel will ignite), auto-ignitiontemperature, and the rate of combustion. Eachof these properties is controlled by the molecu-lar structure of the fuel. Eventually, through aniterative process, designer fuels can be opti-mized for high performance and low pollutants.

NREL researchers are just beginning this process.Their aim is to do it first for diesel with moreconventional fossil-fuel stock, then to turn to re-newable stock, and finally, to pass beyonddiesel to other fuels.

Designing fuels at the molecular level is justone part of a multifaceted effort that NRELis engaged in to help the nation moveaway from foreign sources of oil, towardan infrastructure that includes a large per-centage of renewable fuels and advancedvehicles and that may eventually culmi-nate in zero emissions.

NREL and its partners in industryand academia developed a newfilter and fuel system that slashesparticulate emissions from heavy-duty diesel trucks by 97%, cutscarbon monoxide emissions bymore than 80%, and reduces to-tal hydrocarbon emissions to be-low detection limits.

The system consists of a low-sulfurdiesel fuel used in combinationwith either of two self-regenerat-ing particulate filters. The fuel,which was developed by ARCO,contains less than 15 ppm of sul-fur, is made using a conventionalrefinery process, does not requirespecial handling, and is availableon the California market.

The filters were developed byEngelhard and by JohnsonMatthey. Each filter—installed inplace of a muffler—is a cat-alyzed filter that oxidizes partic-ulate matter, carbon monoxide,and unburned carbons from thediesel exhaust. Because they oxi-dize particulate matter at low ex-haust temperatures, the filtersregenerate themselves and donot need to be routinely serv-iced. Both filters have been certi-fied by the California AirResources Board as being able tomeet the new, strict emissionsstandards to be phased in from2007 to 2010.

Breathing Easier

NREL and its partnersexplore many optionsfor reducing emissionsfrom diesel fuels. Oneoption is this speciallydesigned heavy-truckengine. The design re-duces the temperatureat which ignition occurs(to lower NOx emis-sions); modifies the pis-ton shape to increasethe volume of gas in thecombustion chamber(to lower ignition tem-perature); and re-circu-lates exhaust gasesproduced by each pis-ton stroke (lowering theoxygen in the mixture,and hence loweringNOx). When used witha Fischer-Tropsch Fuel,this approach reducesemissions of NOx andparticulate matter bymore than 90% com-pared to conventionaldiesel engines.

One way to lowerdiesel emissions is touse the Fischer-Tropschprocess to produceclean synthetic diesel,such as this fuel,which contains nosulfur and very fewaromatics. Anotherway NREL is exploringis to design the fuelfrom the molecularlevel, to achieve notonly low emissions buthigh performance.

Inlet air

Turbine compressor

Fischer-Tropschsynthetic diesel fuel

Conventionaldiesel fuel

Intercooler

Cooler

Exhaust

EGRvalve

Catalyzedparticle

filter

Two-stagelean-NOxcatalyst

Exhaustcooler

Secondaryfuel

injector

Fischer-Tropschfuel improves ef-ficiency of aftertreatment de-

vices

Exhaust GasRecirculation(EGR) lowerscombustiontemperatureand reduces

NOxformation

One way of reaching our goals onenergy, emissions, and infrastruc-ture is, to coin a phase, to just doit—find ways in which to put morealternative-fuel vehicles (AFVs) onthe road, and ways for those vehi-cles to use more alternative fuels.The DOE-sponsored Clean Citiesprogram is finding ways. This pro-gram helps build coalitions amonggovernment agencies and privatecompanies to promote the pur-chase of AFVs, the use of alterna-tive fuels, and the expansion ofrefueling stations for those fuels.The coalition members can lever-age their resources, collaborate onpublic policy issues, promote AFVsin their community, and help cre-ate AFV markets.

Opportunities are greatest in mar-kets where fleets of vehicles canshare their use of the infrastruc-ture. This includes airports, cam-puses, military bases, governmentagencies, transit agencies, andfreight and package delivery com-panies. By tapping these markets,the program and its cooperatingmembers have built coalitions inmore than 80 cities and 41 states.There are about 400,000 AFVs on

the road today. And today, driversare discovering a growing infra-structure of stations where theycan fill up their tanks with com-pressed natural gas (CNG), E85(a blend containing 85% ethanoland 15% gasoline), and other al-ternative fuels.

Two of the aims of this coalition-building effort are to get 1 millionAFVs on the road by 2010 and tohave these vehicles consume 1 bil-lion equivalent gallons of alterna-tive fuels. But the long-term goal isto build a sustainable alternative-fuel market, and thereby enhanceenergy security and air quality.

Clearing the Air

SuperShuttle, a van service that provides shared,door-to-door rides to seven major airports acrossthe country, operates approximately 300 CNG vehi-cles. This one is filling up with CNG at the DenverInternational Airport.

9

battery. Temperature variations from module tomodule can affect performance and life. Ouranalysis can point to ways in which to manage thetemperature of the battery subsystems, for best per-formance (see sidebar “Going Farther for Less”).

Other important subsystems are those that helpdetermine the comfort of the passenger—heat-ing, ventilation, cooling, and keeping the airclean. These auxiliary systems can consume alarge amount of energy. NREL uses an optimiza-tion approach to analyze auxiliary loads, simul-taneously modeling passenger comfort, heatingand air-conditioning, and vehicle performanceto determine how best to keep passengers com-fortable while minimizing fuel use and emis-sions. This systems approach, which canminimize auxiliary loads while increasing vehi-cle performance and passenger comfort, couldsave the nation billions of gallons of gasolineper year—to painlessly reduce our dependenceon foreign oil and enhance air quality.

develops these fuels through its biofuels andbiomass programs (see “Biorefineries” on pages2-5). These fuels are most often blended withgasoline—a strategy that not only gets more al-ternative fuels into the energy infrastructure, butalso helps curtail emissions.

A third step is to produce hydrogen from renew-able resources for use as both a fuel and an en-ergy carrier. This will dovetail nicely with theparallel development of fuel-cell vehicles. NRELpursues this alternative through its research inbasic energy sciences and through the DOE’shydrogen program (see “Hydrogen Economy”on pages 10-13).

The Heavy-duty Option. Another option for re-ducing emissions is to develop clean diesel fuelsfor heavy-duty vehicles. Diesel fuel accounts foralmost 20% of the fuel used on our highways,and its use in on-road heavy-duty vehicles gen-erates thousands of tons of nitrogen oxides, par-ticulate matter, and other pollutants each year.Working with industry, NREL has helped devel-op technologies and approaches in which dieselemissions can be drastically cut.

One approach byNREL and itspartners is todevelop clean“conventional”

diesel fuels for use with catalyzed filters (seesidebar “Breathing Easier”). A second approachis to develop clean synthetic fuels from naturalgas (or synthesis gas—primarily hydrogen andcarbon monoxide) in conjunction with modify-ing a diesel engine to optimally burn the syn-thetic diesel. With this approach, carbonmonoxide emissions can be nearly eliminated,while particulate matter and nitrogen oxidescan be reduced by up to 97%.

Designer Fuels. A further strategy is to designdiesel fuels on the molecular level. In this way,you can design for particular properties of a fu-el—such as the cetane number (a measure ofhow readily the fuel will ignite), auto-ignitiontemperature, and the rate of combustion. Eachof these properties is controlled by the molecu-lar structure of the fuel. Eventually, through aniterative process, designer fuels can be opti-mized for high performance and low pollutants.

NREL researchers are just beginning this process.Their aim is to do it first for diesel with moreconventional fossil-fuel stock, then to turn to re-newable stock, and finally, to pass beyonddiesel to other fuels.

Designing fuels at the molecular level is justone part of a multifaceted effort that NRELis engaged in to help the nation moveaway from foreign sources of oil, towardan infrastructure that includes a large per-centage of renewable fuels and advancedvehicles and that may eventually culmi-nate in zero emissions.

NREL and its partners in industryand academia developed a newfilter and fuel system that slashesparticulate emissions from heavy-duty diesel trucks by 97%, cutscarbon monoxide emissions bymore than 80%, and reduces to-tal hydrocarbon emissions to be-low detection limits.

The system consists of a low-sulfurdiesel fuel used in combinationwith either of two self-regenerat-ing particulate filters. The fuel,which was developed by ARCO,contains less than 15 ppm of sul-fur, is made using a conventionalrefinery process, does not requirespecial handling, and is availableon the California market.

The filters were developed byEngelhard and by JohnsonMatthey. Each filter—installed inplace of a muffler—is a cat-alyzed filter that oxidizes partic-ulate matter, carbon monoxide,and unburned carbons from thediesel exhaust. Because they oxi-dize particulate matter at low ex-haust temperatures, the filtersregenerate themselves and donot need to be routinely serv-iced. Both filters have been certi-fied by the California AirResources Board as being able tomeet the new, strict emissionsstandards to be phased in from2007 to 2010.

Breathing Easier

NREL and its partnersexplore many optionsfor reducing emissionsfrom diesel fuels. Oneoption is this speciallydesigned heavy-truckengine. The design re-duces the temperatureat which ignition occurs(to lower NOx emis-sions); modifies the pis-ton shape to increasethe volume of gas in thecombustion chamber(to lower ignition tem-perature); and re-circu-lates exhaust gasesproduced by each pis-ton stroke (lowering theoxygen in the mixture,and hence loweringNOx). When used witha Fischer-Tropsch Fuel,this approach reducesemissions of NOx andparticulate matter bymore than 90% com-pared to conventionaldiesel engines.

One way to lowerdiesel emissions is touse the Fischer-Tropschprocess to produceclean synthetic diesel,such as this fuel,which contains nosulfur and very fewaromatics. Anotherway NREL is exploringis to design the fuelfrom the molecularlevel, to achieve notonly low emissions buthigh performance.

Inlet air

Turbine compressor

Fischer-Tropschsynthetic diesel fuel

Conventionaldiesel fuel

Intercooler

Cooler

Exhaust

EGRvalve

Catalyzedparticle

filter

Two-stagelean-NOxcatalyst

Exhaustcooler

Secondaryfuel

injector

Fischer-Tropschfuel improves ef-ficiency of aftertreatment de-

vices

Exhaust GasRecirculation(EGR) lowerscombustiontemperatureand reduces

NOxformation

Hydrogen is the simplest element in theuniverse. It is also the most abundant ele-ment, constituting more that 90% of theatoms of the universe and 75% of its mass.It is the third most abundant element inthe Earth’s surface and is found mostly incombination with oxygen as water (H2O).

As a gas (H2), it is colorless, odorless,tasteless, and non-poisonous.

Hydrogen also may be one of thebest bets to fuel the future economy

of America and the world.Why? First, it is widely dis-tributed in many resources.Hydrogen is not only presentin water, but is in fossil fuels,like petroleum, coal, andnatural gas, and it is inplants and organic waste.Hydrogen can be producedfrom these resources usingelectrolytic, thermochemical,or photolytic processes.

Second, as a fuel, hydrogenis clean. Solar energy canprovide the electricity to splitwater into its constituent ele-ments of hydrogen and oxy-gen (see sidebar “Solid-StateWater Splitting”). The hydro-gen then can be used in a

fuel cell, where hydrogen and oxygen from airrecombine to generate electricity, heat, andwater (see sidebar “Fuel Cells”). Deriving andusing hydrogen in this manner produces noparticulates, carbon dioxide, or pollution.

Third, hydrogen is versatile. We can producehydrogen at one location or time to store en-ergy and then distribute it to release the ener-gy at another time or place. Hydrogen can beused to generate electricity, through the use offuel cells, turbines, or microturbines. It cansupply us with heat, warm our buildings, orpower industrial processes. It can be used ininternal combustion engines to power ourcars, trucks, and buses, or in fuel cells for thesame purpose. It can provide power for ourjetliners and ocean fleets. Because fuel cellsare modular, hydrogen can be used for bothsmall- and large-scale applications—to pro-vide heat and electricity for single homes or to

supply the energyto run an entire

large com-mercial

building; to provide a small amount of elec-tricity to a community grid, or a large amountof electricity to a large grid network.

The Road to the Hydrogen Economy

In the coming hydrogen economy, hydrogenwill serve, along with electricity, as the na-tion’s energy carrier. When hydrogen is pro-duced from renewable energy sources—wind,solar energy, biomass, water—America willhave an inexhaustible supply of clean,domestically produced energy.

Although making the transition to arenewable hydrogen economy willtake decades, we are already startingdown the road toward an energyeconomy based on hydrogen andelectricity. NREL is working with in-dustry, universities, the Department ofEnergy, and other national laboratories tooutline the steps required to realize our visionof a hydrogen economy. The transition willbegin by building on current infrastructuresand capabilities; future progress will dependon developing and commercializing a range oftechnologies for using, producing, storing, anddistributing hydrogen.

Using Hydrogen. An essential driver for reach-ing a hydrogen economy is to increase the useof hydrogen. Today, the United States uses

Fuel CellsA fuel cell is a device somewhatlike a battery—it produces elec-tricity electrochemically. Unlike abattery, it does not need to beelectrically recharged because ituses an external fuel source, hy-

drogen gas, to generate electric-ity as long as hydrogen fuel

is supplied.

A typical fuel cell employsa catalyzed membranesandwiched between anegative electrode (an-ode) and a positive elec-trode (cathode). Oxygenflows into the fuel cell on

the cathode side.Hydrogen flows into the

cell on the anode side,where the catalyst separates

the hydrogen atoms into protons

(hydrogen ions) and electrons. Theelectrons are attracted to the cath-ode, but they are blocked by themembrane. Consequently, theyflow to the cathode through an ex-ternal circuit, creating a current ofelectricity. The protons are attract-ed by the oxygen at the cathodeand flow through the membrane,where they combine with the elec-trons and the oxygen to produceheat and water.

Individual fuel cells can be com-bined into a fuel-cell stack. Thismodular design capability allowsfuel-cell stacks to produce enoughelectric power or heat for almostany size application. In addition,by putting both the heat and elec-tricity to effective use, a fuel cellcould be 80% to 90% efficient.

Scientists have known for decadesthat green algae can produce hydro-gen. Researchers at NREL, ORNL,and the University of California atBerkeley have unlocked the secret toincreasing the hydrogen yield of acertain type of green microalgae—Chlamydomonas reinhardtii—whichshows promise of producing hydro-gen cheaply, easily, and cleanly.

The process they’ve developed in-volves interrupting the algae’s normalphotosynthesis process. These algae,like all green plants, use photosynthe-sis—i.e., in the presence of light they“inhale” carbon dioxide and “exhale”

oxygen. But hydrogenase—an enzyme that produceshydrogen—shuts down in the presence of oxygen, inthe daylight, during prime photosynthesis time. Thisconfines the algae’s production of hydrogen to night-

time when photosynthesis does not occur, limiting theamount of hydrogen produced.

To overcome this limitation, the scientists developed atwo-step method that allows the algae to make hydro-gen while the sun shines. First they grow out (“fatten”)the algae under normal photosynthetic conditions.Second, they withhold sulfur which, the scientists dis-covered, is essential for this green algae to maintainnormal photosynthesis. Without sulfur, the algae stopemitting oxygen and stop storing energy. Instead, theyswitch to a new metabolic pathway—one that exploitsstored energy reserves in the absence of net oxygenproduction. This kicks the hydrogenase into high gearto release large amounts of hydrogen.

This process induces the algae to produce 100,000 timesmore hydrogen than they do under normal conditions. Plus,the researchers have developed a process to fatten the algaeagain on a diet of sunshine and sulfur, and then to starve thealgae of sulfur again to produce hydrogen. This cycle canbe repeated several times. Still, much work remains to bedone to make the process feasible on a larger scale.

The fuel cell (of whicha typical schematic isshown) is essentialto the hydrogeneconomy and mayhelp revolutionizethe way in whichwe use energy inAmerica. Using hy-drogen as fuel, fuelcells will power ourtransportation, provideelectricity, and heat andcool our buildings. Allwithout producing pollutionor greenhouse gases.

The hydrogen cycle: Whengenerated from renewablesources, hydrogen produc-tion and use is part of aclean, cyclic process.

NASA's space shuttle (top) uses liquid hydro-gen and oxygen for propulsion and hydrogen-

powered fuel cells to provide onboardelectricity and water. Car manufacturers

(bottom) are beginning to produce vehiclespowered by fuel cells. (Shuttle photo and Eagle

Nebula photo in the background and on the frontcover are courtesy of NASA.)

A scientistscrutinizes a

flask contain-ing microalgae

for hydrogenproduction.

10 11

Harvesting Hydrogen from Microalgae

Hydrogen is the simplest element in theuniverse. It is also the most abundant ele-ment, constituting more that 90% of theatoms of the universe and 75% of its mass.It is the third most abundant element inthe Earth’s surface and is found mostly incombination with oxygen as water (H2O).

As a gas (H2), it is colorless, odorless,tasteless, and non-poisonous.

Hydrogen also may be one of thebest bets to fuel the future economy

of America and the world.Why? First, it is widely dis-tributed in many resources.Hydrogen is not only presentin water, but is in fossil fuels,like petroleum, coal, andnatural gas, and it is inplants and organic waste.Hydrogen can be producedfrom these resources usingelectrolytic, thermochemical,or photolytic processes.

Second, as a fuel, hydrogenis clean. Solar energy canprovide the electricity to splitwater into its constituent ele-ments of hydrogen and oxy-gen (see sidebar “Solid-StateWater Splitting”). The hydro-gen then can be used in a

fuel cell, where hydrogen and oxygen from airrecombine to generate electricity, heat, andwater (see sidebar “Fuel Cells”). Deriving andusing hydrogen in this manner produces noparticulates, carbon dioxide, or pollution.

Third, hydrogen is versatile. We can producehydrogen at one location or time to store en-ergy and then distribute it to release the ener-gy at another time or place. Hydrogen can beused to generate electricity, through the use offuel cells, turbines, or microturbines. It cansupply us with heat, warm our buildings, orpower industrial processes. It can be used ininternal combustion engines to power ourcars, trucks, and buses, or in fuel cells for thesame purpose. It can provide power for ourjetliners and ocean fleets. Because fuel cellsare modular, hydrogen can be used for bothsmall- and large-scale applications—to pro-vide heat and electricity for single homes or to

supply the energyto run an entire

large com-mercial

building; to provide a small amount of elec-tricity to a community grid, or a large amountof electricity to a large grid network.

The Road to the Hydrogen Economy

In the coming hydrogen economy, hydrogenwill serve, along with electricity, as the na-tion’s energy carrier. When hydrogen is pro-duced from renewable energy sources—wind,solar energy, biomass, water—America willhave an inexhaustible supply of clean,domestically produced energy.

Although making the transition to arenewable hydrogen economy willtake decades, we are already startingdown the road toward an energyeconomy based on hydrogen andelectricity. NREL is working with in-dustry, universities, the Department ofEnergy, and other national laboratories tooutline the steps required to realize our visionof a hydrogen economy. The transition willbegin by building on current infrastructuresand capabilities; future progress will dependon developing and commercializing a range oftechnologies for using, producing, storing, anddistributing hydrogen.

Using Hydrogen. An essential driver for reach-ing a hydrogen economy is to increase the useof hydrogen. Today, the United States uses

Fuel CellsA fuel cell is a device somewhatlike a battery—it produces elec-tricity electrochemically. Unlike abattery, it does not need to beelectrically recharged because ituses an external fuel source, hy-

drogen gas, to generate electric-ity as long as hydrogen fuel

is supplied.

A typical fuel cell employsa catalyzed membranesandwiched between anegative electrode (an-ode) and a positive elec-trode (cathode). Oxygenflows into the fuel cell on

the cathode side.Hydrogen flows into the

cell on the anode side,where the catalyst separates

the hydrogen atoms into protons

(hydrogen ions) and electrons. Theelectrons are attracted to the cath-ode, but they are blocked by themembrane. Consequently, theyflow to the cathode through an ex-ternal circuit, creating a current ofelectricity. The protons are attract-ed by the oxygen at the cathodeand flow through the membrane,where they combine with the elec-trons and the oxygen to produceheat and water.

Individual fuel cells can be com-bined into a fuel-cell stack. Thismodular design capability allowsfuel-cell stacks to produce enoughelectric power or heat for almostany size application. In addition,by putting both the heat and elec-tricity to effective use, a fuel cellcould be 80% to 90% efficient.

Scientists have known for decadesthat green algae can produce hydro-gen. Researchers at NREL, ORNL,and the University of California atBerkeley have unlocked the secret toincreasing the hydrogen yield of acertain type of green microalgae—Chlamydomonas reinhardtii—whichshows promise of producing hydro-gen cheaply, easily, and cleanly.

The process they’ve developed in-volves interrupting the algae’s normalphotosynthesis process. These algae,like all green plants, use photosynthe-sis—i.e., in the presence of light they“inhale” carbon dioxide and “exhale”

oxygen. But hydrogenase—an enzyme that produceshydrogen—shuts down in the presence of oxygen, inthe daylight, during prime photosynthesis time. Thisconfines the algae’s production of hydrogen to night-

time when photosynthesis does not occur, limiting theamount of hydrogen produced.

To overcome this limitation, the scientists developed atwo-step method that allows the algae to make hydro-gen while the sun shines. First they grow out (“fatten”)the algae under normal photosynthetic conditions.Second, they withhold sulfur which, the scientists dis-covered, is essential for this green algae to maintainnormal photosynthesis. Without sulfur, the algae stopemitting oxygen and stop storing energy. Instead, theyswitch to a new metabolic pathway—one that exploitsstored energy reserves in the absence of net oxygenproduction. This kicks the hydrogenase into high gearto release large amounts of hydrogen.

This process induces the algae to produce 100,000 timesmore hydrogen than they do under normal conditions. Plus,the researchers have developed a process to fatten the algaeagain on a diet of sunshine and sulfur, and then to starve thealgae of sulfur again to produce hydrogen. This cycle canbe repeated several times. Still, much work remains to bedone to make the process feasible on a larger scale.

The fuel cell (of whicha typical schematic isshown) is essentialto the hydrogeneconomy and mayhelp revolutionizethe way in whichwe use energy inAmerica. Using hy-drogen as fuel, fuelcells will power ourtransportation, provideelectricity, and heat andcool our buildings. Allwithout producing pollutionor greenhouse gases.

The hydrogen cycle: Whengenerated from renewablesources, hydrogen produc-tion and use is part of aclean, cyclic process.

NASA's space shuttle (top) uses liquid hydro-gen and oxygen for propulsion and hydrogen-

powered fuel cells to provide onboardelectricity and water. Car manufacturers

(bottom) are beginning to produce vehiclespowered by fuel cells. (Shuttle photo and Eagle

Nebula photo in the background and on the frontcover are courtesy of NASA.)

A scientistscrutinizes a

flask contain-ing microalgae

for hydrogenproduction.

11

Harvesting Hydrogen from Microalgae

12

more than 90 billion cubic meters (3.2 trillioncubic feet) of hydrogen annually. The greatmajority of this is used for refining petroleum,making plastics, and producing fertilizers.Demonstrations are now under way to provehydrogen’s potential for transportation, for pro-ducing electricity, and for providing heat andelectricity to buildings—all of which will helpspur the growth of the hydrogen economy.Take transportation as an example. Initially wemay witness the growth of hydrogen-fueledinternal combustion engines—building on cur-rent transportation technologies and infrastruc-ture. Ultimately, however, fuel cells will beintegral to transportation (as well as to build-ings, industry, and utilities). We will see fuelcells being incorporated into hybrid electricvehicles (which use both fuel-cell electricityand internal combustion), in which they willreplace the engine. And eventually, fuel cellswill provide the power for advanced fuel-cellvehicles (see also “Transportation Technologies”on pages 6-9).

Producing Hydrogen. Almost all of the hydro-gen produced today is made by steam refor-mation of natural gas. For the near term, thismethod of production will continue to domi-

nate. Hydrogen can also be produced by thegasification of coal or the partial oxidation ofoil. Near-term improvements in these fossil-fuel-based processes will allow for the cap-ture of the carbon dioxide byproduct, whichcan then be sequestered (stored or lockedaway). In the mid term, we’ll see renewableenergy technologies taking a larger role—viagasification or pyrolysis of biomass (see“Biorefineries” on pages 2-5) or via electroly-sis of water with electricity produced by windenergy or other renewable electric technolo-gies. Eventually, through long-term R&D, hy-drogen will be produced directly usingphotobiological or photolytic processes (seesidebars “Harvesting Hydrogen from Micro-algae” and “Solid-State Water Splitting”), inwhich hydrogen will be derived directly fromsunlight and water.

Storing Hydrogen. Today, we store hydrogenas a compressed gas under high pressure or asa liquid at cryogenic temperatures. These willcontinue to be the primary means of storagefor quite some time. There is also a possibilitythat we soon may be able to store hydrogenonboard vehicles or at the point of use asgasoline, methanol, or some other hydrogen-

rich material, fromwhich it could beextracted using areformer (whichbreaks down hy-drogen-carbonbonds to pro-duce a gas fromwhich hydrogen

is obtained). In the meantime, research willcontinue to explore ways in which to storehydrogen in chemical or metal hydrides or incarbon nanotubes. These long-term optionscould provide safe and high-density storage,reducing storage space and providing a rangethat could be greater than that provided byconventional vehicles (see sidebar “StoringHydrogen in Nanotubes”).

Distributing Hydrogen. America has an ex-tensive distribution network for its energy.There are more than 3 million miles ofpipelines for transporting natural gas and pe-troleum, 160,000 miles of high-voltage trans-mission lines, and thousands of tankers andtrucks. And there are tens of thousands of gasstations for dispensing gasoline. This network

is characterized by centralized productionwith distribution to regional and local mar-kets. Hydrogen itself is transported primarilyby truck, but also by tankers and pipeline. Inthe near term, hydrogen for energy will usethe existing distribution systems. But as de-mand grows in the future, we could see natu-ral gas piped to regional locations, where itwill be reformed to hydrogen for regionaldistribution. Farther into the future, asproduction from renewable energysources and technologies becomes lessexpensive, we may see hydrogen producedboth regionally and locally, and distributedlocally. Thus, the emerging hydrogen econo-my will not only provide secure and clean en-ergy for the nation, but also will provide localcommunities with an important economicbase from which to grow.

Today, most all hydrogenis produced via steam ref-ormation of natural gas at

oil refineries. The greatmajority of that hydrogen

is used by oil refineriesand petrochemical plantsto refine fuel and to make

industrial commodities.

This photovoltaic system at SunLine Transit Agency in Thou-sand Palms, California, provides electricity for the StuartEnergy electrolysis unit (on the right).

The energy density (energy permass) of hydrogen is more thanthree times that of gasoline. Theproblem is, because hydrogen is solight, it requires a large volume tostore an appropriate amount of hy-drogen energy onboard a vehicle.To overcome this, we can store thehydrogen at very low temperatures,under high pressure as a com-pressed gas, in chemical or metalhydrides (materials that reversiblyabsorb hydrogen), or even in liquidhydrocarbons that can be reformedto hydrogen on demand.

A team of NREL scientists is pursu-ing a novel and promising long-term solution: storage of hydrogenin carbon nanotubes—hollowtubes of carbon 1-2 nanometers indiameter. The walls of the tubesare made of a single layer of car-bon atoms arranged in hexagonalpatterns. These tubes can absorband safely store high volumes of

hydrogen in a small space at nor-mal operating conditions. Thestored hydrogen can be releasedon demand through small changesin temperature and pressure.

Researchers have been able tomake some very pure carbon nan-otubes that appear to be ableto store up to 67 kilogramsof hydrogen per cubic meter(kg/m3). At such a capaci-ty—which surpasses thegoal of 62 kg/m3 set by theDepartment of Energy—itwould take only about0.075 cubic meters to store5 kilograms of hydrogen,which is about the size ofgas tanks used in some cars andsmall trucks today. With thisamount of stored hydrogen, anadvanced fuel-cell car shouldbe able to travel farther on atank than today’s typical car orsmall truck.

Storing Hydrogen in Nanotubes

The cleanest way to produce hy-drogen is by using sunlight to di-rectly split water into hydrogenand oxygen. All you need is sun-light and water, and an appropri-ate system to split the water.

NREL scientists have devisedsuch a system, in which a multi-junction solar cell is immersed inan aqueous electrolytic solution.The top cell in the structure(made of gallium indium phos-phide—GaInP2) absorbs the high-energy photons in the solarspectrum to produce electron-hole pairs. The bottom cell (made

of gallium arsenide—GaAs)does likewise with thelower-energy photons thatpass through the top cell.The electrons flow towardthe illuminated surfaceand the electrolytic-GaInP2 interface, whichserves as a cathode forthe system. Holes travel

to the GaAs bottom surface,which is coated with platinum toprovide an ohmic contact. Thetandem cell provides a sufficientvoltage to drive an oxidation-re-duction reaction that produceshydrogen at the cathode and oxy-gen at a platinum anode.

This NREL system produces elec-tricity from sunlight without theexpense and complication ofelectrolyzers—and at 12.4% so-lar-to-hydrogen efficiency, doesso more efficiently than otherphotolytic approaches. This ap-proach represents one possiblelong-term solution for the sus-tainable production of hydrogen.In the meantime, there remainsmuch to be explored, includingnon-aqueous electrolytes, alter-nate semiconductor systems, andlower-cost materials that maylead to the commercial produc-tion of hydrogen from sunlightand water.

An NREL scientist holds a beaker contain-ing a photolytic device submerged in analkaline aqueous solution. This configura-tion produces hydrogen from water withgreater than 12% efficiency.

13

Solid-State Water Splitting

Carbon nanotubes carrythe promise of being

able to store high vol-umes of hydrogen and

to release the hydrogenon demand.

more than 90 billion cubic meters (3.2 trillioncubic feet) of hydrogen annually. The greatmajority of this is used for refining petroleum,making plastics, and producing fertilizers.Demonstrations are now under way to provehydrogen’s potential for transportation, for pro-ducing electricity, and for providing heat andelectricity to buildings—all of which will helpspur the growth of the hydrogen economy.Take transportation as an example. Initially wemay witness the growth of hydrogen-fueledinternal combustion engines—building on cur-rent transportation technologies and infrastruc-ture. Ultimately, however, fuel cells will beintegral to transportation (as well as to build-ings, industry, and utilities). We will see fuelcells being incorporated into hybrid electricvehicles (which use both fuel-cell electricityand internal combustion), in which they willreplace the engine. And eventually, fuel cellswill provide the power for advanced fuel-cellvehicles (see also “Transportation Technologies”on pages 6-9).

Producing Hydrogen. Almost all of the hydro-gen produced today is made by steam refor-mation of natural gas. For the near term, thismethod of production will continue to domi-

nate. Hydrogen can also be produced by thegasification of coal or the partial oxidation ofoil. Near-term improvements in these fossil-fuel-based processes will allow for the cap-ture of the carbon dioxide byproduct, whichcan then be sequestered (stored or lockedaway). In the mid term, we’ll see renewableenergy technologies taking a larger role—viagasification or pyrolysis of biomass (see“Biorefineries” on pages 2-5) or via electroly-sis of water with electricity produced by windenergy or other renewable electric technolo-gies. Eventually, through long-term R&D, hy-drogen will be produced directly usingphotobiological or photolytic processes (seesidebars “Harvesting Hydrogen from Micro-algae” and “Solid-State Water Splitting”), inwhich hydrogen will be derived directly fromsunlight and water.

Storing Hydrogen. Today, we store hydrogenas a compressed gas under high pressure or asa liquid at cryogenic temperatures. These willcontinue to be the primary means of storagefor quite some time. There is also a possibilitythat we soon may be able to store hydrogenonboard vehicles or at the point of use asgasoline, methanol, or some other hydrogen-

rich material, fromwhich it could beextracted using areformer (whichbreaks down hy-drogen-carbonbonds to pro-duce a gas fromwhich hydrogen

is obtained). In the meantime, research willcontinue to explore ways in which to storehydrogen in chemical or metal hydrides or incarbon nanotubes. These long-term optionscould provide safe and high-density storage,reducing storage space and providing a rangethat could be greater than that provided byconventional vehicles (see sidebar “StoringHydrogen in Nanotubes”).

Distributing Hydrogen. America has an ex-tensive distribution network for its energy.There are more than 3 million miles ofpipelines for transporting natural gas and pe-troleum, 160,000 miles of high-voltage trans-mission lines, and thousands of tankers andtrucks. And there are tens of thousands of gasstations for dispensing gasoline. This network

is characterized by centralized productionwith distribution to regional and local mar-kets. Hydrogen itself is transported primarilyby truck, but also by tankers and pipeline. Inthe near term, hydrogen for energy will usethe existing distribution systems. But as de-mand grows in the future, we could see natu-ral gas piped to regional locations, where itwill be reformed to hydrogen for regionaldistribution. Farther into the future, asproduction from renewable energysources and technologies becomes lessexpensive, we may see hydrogen producedboth regionally and locally, and distributedlocally. Thus, the emerging hydrogen econo-my will not only provide secure and clean en-ergy for the nation, but also will provide localcommunities with an important economicbase from which to grow.

Today, most all hydrogenis produced via steam ref-ormation of natural gas at

oil refineries. The greatmajority of that hydrogen

is used by oil refineriesand petrochemical plantsto refine fuel and to make

industrial commodities.

This photovoltaic system at SunLine Transit Agency in Thou-sand Palms, California, provides electricity for the StuartEnergy electrolysis unit (on the right).

The energy density (energy permass) of hydrogen is more thanthree times that of gasoline. Theproblem is, because hydrogen is solight, it requires a large volume tostore an appropriate amount of hy-drogen energy onboard a vehicle.To overcome this, we can store thehydrogen at very low temperatures,under high pressure as a com-pressed gas, in chemical or metalhydrides (materials that reversiblyabsorb hydrogen), or even in liquidhydrocarbons that can be reformedto hydrogen on demand.

A team of NREL scientists is pursu-ing a novel and promising long-term solution: storage of hydrogenin carbon nanotubes—hollowtubes of carbon 1-2 nanometers indiameter. The walls of the tubesare made of a single layer of car-bon atoms arranged in hexagonalpatterns. These tubes can absorband safely store high volumes of

hydrogen in a small space at nor-mal operating conditions. Thestored hydrogen can be releasedon demand through small changesin temperature and pressure.

Researchers have been able tomake some very pure carbon nan-otubes that appear to be ableto store up to 67 kilogramsof hydrogen per cubic meter(kg/m3). At such a capaci-ty—which surpasses thegoal of 62 kg/m3 set by theDepartment of Energy—itwould take only about0.075 cubic meters to store5 kilograms of hydrogen,which is about the size ofgas tanks used in some cars andsmall trucks today. With thisamount of stored hydrogen, anadvanced fuel-cell car shouldbe able to travel farther on atank than today’s typical car orsmall truck.

Storing Hydrogen in Nanotubes

The cleanest way to produce hy-drogen is by using sunlight to di-rectly split water into hydrogenand oxygen. All you need is sun-light and water, and an appropri-ate system to split the water.

NREL scientists have devisedsuch a system, in which a multi-junction solar cell is immersed inan aqueous electrolytic solution.The top cell in the structure(made of gallium indium phos-phide—GaInP2) absorbs the high-energy photons in the solarspectrum to produce electron-hole pairs. The bottom cell (made

of gallium arsenide—GaAs)does likewise with thelower-energy photons thatpass through the top cell.The electrons flow towardthe illuminated surfaceand the electrolytic-GaInP2 interface, whichserves as a cathode forthe system. Holes travel

to the GaAs bottom surface,which is coated with platinum toprovide an ohmic contact. Thetandem cell provides a sufficientvoltage to drive an oxidation-re-duction reaction that produceshydrogen at the cathode and oxy-gen at a platinum anode.

This NREL system produces elec-tricity from sunlight without theexpense and complication ofelectrolyzers—and at 12.4% so-lar-to-hydrogen efficiency, doesso more efficiently than otherphotolytic approaches. This ap-proach represents one possiblelong-term solution for the sus-tainable production of hydrogen.In the meantime, there remainsmuch to be explored, includingnon-aqueous electrolytes, alter-nate semiconductor systems, andlower-cost materials that maylead to the commercial produc-tion of hydrogen from sunlightand water.

An NREL scientist holds a beaker contain-ing a photolytic device submerged in analkaline aqueous solution. This configura-tion produces hydrogen from water withgreater than 12% efficiency.

Hydrogen-powered vehicles, which are becomingmore popular, include SUVs and fleets of buses. TheSunLine Transit Agency, for example, uses two busespowered by a mixture of hydrogen and natural gas,and one bus powered by hydrogen fuel cells.

13

Solid-State Water Splitting

Carbon nanotubes carrythe promise of being

able to store high vol-umes of hydrogen and

to release the hydrogenon demand.

Something asseemingly sim-ple as saran

wrap. Thin—verythin —layers ofstacked plasticsheets could repre-sent the future ofelectricity. Thosethin sheets are

conductive polymers with embedded nanorods orquantum dots of semiconductor material that oneday may produce electricity from the sun to pow-er homes and businesses.

Fanciful? Perhaps. But plastic solar cells serve as abenchmark for how far we’ve come since the mid-dle of the 1970s, when solar electricity was only areality for powering satellites and was still too ex-pensive for uses on Earth. And they are a harbingerof what is to come. The first steps toward plasticsolar cells have been taken by researchers at uni-versities and research organizations under an NRELprogram. Scientists can convert from 2% to nearly5% of sunlight to electricity (depending on the ap-proach). And prospects look good for bumpingconversion efficiencies well beyond 10%, towardviability and toward solar electricity that couldsomeday cost less than 2¢/kWh.

This is part of the promise of the emerging solarelectric revolution. Solar electricity is the ultimate

distributed energy. Solar electric systems canprovide electricity anywhere in anyamount—from a few watts to billions of

watts. Solar electricity is comingto America along two generaltechnological pathways. Oneof these pathways is photo-voltaics (PV or solar cells)—in which photons dislodgeelectrons in solid-state materi-als to directly convert sun-light to electricity. The otheris concentrating solar pow-er—in which the heat ofconcentrated sunlight is usedto generate electricity.

Solar-CellGenerations

In 1977, when NREL first be-gan its research on solarcells, the world producedless than 50,000 watts of so-lar cells; they were based oncrystalline silicon wafer tech-

nology, and most werefor use in space. Today,we are developing andexploring a wide range ofmaterial and device tech-nologies, the worldwidemarket is growing by 30%to 40% per year and isfast approaching 500million watts per year.

Several things arespurring this growth.First is the search fordependable alternativeelectricity systems thatcan be used in a dis-tributive sense—togenerate electricity atthe point of demand—and that can providesecurity against supplydisruptions, sabotage,or swings in energyprices. Second, PV hasbecome a dependableand versatile technolo-gy. Third, the cost ofelectricity from solarcells has declined more than fourfold since1980 and continues to decline.

In America today, tens of thousands of homesand businesses use PV electricity. By 2030,this number could increase to tens of mil-lions, with PV providing 150 to 200 billionwatts of power. “To get there,” says LarryKazmerski, director of NREL’s National Centerfor Photovoltaics, “solar cells and modulesmust get much cheaper, get much more effi-cient, or both.” NREL and its research partnersin industry and universities are helping topush PV toward the cheaper and better alongseveral generations.

1st Generation—Silicon Wafers. This path isone of continuous incremental improvements.Silicon-wafer technology uses “thick” (150- to300-microns) wafers of crystalline silicon cellsconnected together to form modules andsandwiched between sheets of glass. In 2001,this mature technology constituted about 90%of the solar-cell market. Costs are dominatedby the relatively high cost of semiconductormaterial. Module conversion efficiencies areexpected to increase from today’s 13% to be-yond 16%. As a result of this and improve-ments in manufacturing technology, this path

could drop the cost of solar electricity toaround 7¢/kWh by 2010. This is

good for the short run, butnot as low as we can go in

the long term.

2nd Generation, Part 1—ThinFilms. This technology uses films

of semiconductor material that arefrom 1 to 10 microns thick. Hence,

thin films use far less semiconduc-tor material than does wafer silicon.

Thin-film devices can be made inunits as large as a meter—100 times as largeas a silicon wafer—and can be made in largeruns using mass-production techniques. Thinfilms are versatile and are leading the chargefor today’s specialty, building-integrated appli-cations. For example, thin-film modules canbe made translucent, as shingles for roofs, andincorporated into architectural glass.

NREL has been researching thin-film materialssince the late 1970s. Of these, three haveemerged—amorphous silicon, copper indiumdiselenide, and cadmium telluride. Amorphoussilicon has been building market share sincethe 1980s. The other two are relative new-comers to the market. Currently, the efficiencyof commercial thin-film modules ranges from5% to 11% (depending on the ma-terial and device structure), andcosts are competitive with those ofwafer silicon. But prospects arepromising. For example, by layer-ing thin-film materials on top ofeach other so that different layerscapture and convert different por-tions of the solar spectrum—aconcept known as “multijunc-tion”—modules could eventuallyconvert more than 15% of sunlightto electricity. This, along with im-proved production techniques,could drop electricity costs below4¢/kWh—competitive with mostconventional electricity, but withbuilt-in advantages.

2nd Generation, Part 2—Multi-junction. A third path is throughhigh-efficiency multijunction. Thisis similar to the thin-film multi-junction described above, exceptthat it relies on semiconductor ma-terials that could result in veryhigh efficiencies. These are materi-als primarily from Groups III and V

BP Solar’s new semi-transparent amorphoussilicon modules—devel-oped through participa-tion in the Amorphous

Silicon NationalResearch Team—are

used to provide powerto run pumps, lights,

and other loads at BPgasoline stations.

14

Nanorods and Quantum DotsNREL and its research partners have beeninvestigating semiconductor-related nano-technology since the early 1980s. In 1984,NREL researchers were among the first toreport on quantization effects in nanosizesemiconductor particles related to solarcells. Today, this pioneering research isshowing promising results in the form ofnanorod and quantum-dot solar cells.

Nanorods are semiconductor “wires” thatare a few nanometers wide and up to 100nanometers long (a nanometer is one-bil-lionth of a meter). Embedding nanorods inconductive plastic sheets results in thin,flexible solar cells. The nanorods absorblight of specific wavelengths to generateelectrons and holes (vacancies in the mate-rial that move around similar to electrons).The rods conduct the electrons along theirlength. Holes are transferred to the plastic,

whichconductsthem to an electrode.

Quantum dotsare dots of semi-conductor mate-rial containingfrom just a fewatoms to tens ofthousands ofatoms. Likenanorods, dotscan be embeddedin conductive polymer, or can be used withother materials, such as titanium dioxide. Byvarying their size, quantum dots can be tunedto absorb specific wavelengths of light and sorepresent an avenue toward multi-multijunc-tion devices that could theoretically convertas much as 66% of sunlight to electricity.

Two innovative organic solarcells: The top cell employsnanorods of cadmium seleni-um embedded in conductivepolymer. The bottom cell alsouses a conductive polymersubstrate, but with extremelythin embedded multilayers oforganic molecules.

The 4 Times Square building in Manhattan usesthin-film PV panels to supply 15 kW of power tosupplement the building’s electricity needs. Locatedon the top 14 floors on the south and east sides ofthe building, the PV panels are integrated into thespandrel—the opaque area of the façade belowrows of windows—in 60-inch-wide strips. (AndrewGordon Photography.)

NREL has built what maybe the world’s finest centerfor measuring and charac-terizing photovoltaic andrenewable energy materialsand devices. Shown hereare just a few of the dozensof sophisticated instrumentsused in the center: an XPS,for chemical-bonding infor-mation; a TOF SIMS, forsurface and compositionalanalysis; and an STM, fornanoscale imaging andspectroscopic studies.

Something asseemingly sim-ple as saran

wrap. Thin—verythin —layers ofstacked plasticsheets could repre-sent the future ofelectricity. Thosethin sheets are

conductive polymers with embedded nanorods orquantum dots of semiconductor material that oneday may produce electricity from the sun to pow-er homes and businesses.

Fanciful? Perhaps. But plastic solar cells serve as abenchmark for how far we’ve come since the mid-dle of the 1970s, when solar electricity was only areality for powering satellites and was still too ex-pensive for uses on Earth. And they are a harbingerof what is to come. The first steps toward plasticsolar cells have been taken by researchers at uni-versities and research organizations under an NRELprogram. Scientists can convert from 2% to nearly5% of sunlight to electricity (depending on the ap-proach). And prospects look good for bumpingconversion efficiencies well beyond 10%, towardviability and toward solar electricity that couldsomeday cost less than 2¢/kWh.

This is part of the promise of the emerging solarelectric revolution. Solar electricity is the ultimate

distributed energy. Solar electric systems canprovide electricity anywhere in anyamount—from a few watts to billions of

watts. Solar electricity is comingto America along two generaltechnological pathways. Oneof these pathways is photo-voltaics (PV or solar cells)—in which photons dislodgeelectrons in solid-state materi-als to directly convert sun-light to electricity. The otheris concentrating solar pow-er—in which the heat ofconcentrated sunlight is usedto generate electricity.

Solar-CellGenerations

In 1977, when NREL first be-gan its research on solarcells, the world producedless than 50,000 watts of so-lar cells; they were based oncrystalline silicon wafer tech-

nology, and most werefor use in space. Today,we are developing andexploring a wide range ofmaterial and device tech-nologies, the worldwidemarket is growing by 30%to 40% per year and isfast approaching 500million watts per year.

Several things arespurring this growth.First is the search fordependable alternativeelectricity systems thatcan be used in a dis-tributive sense—togenerate electricity atthe point of demand—and that can providesecurity against supplydisruptions, sabotage,or swings in energyprices. Second, PV hasbecome a dependableand versatile technolo-gy. Third, the cost ofelectricity from solarcells has declined more than fourfold since1980 and continues to decline.

In America today, tens of thousands of homesand businesses use PV electricity. By 2030,this number could increase to tens of mil-lions, with PV providing 150 to 200 billionwatts of power. “To get there,” says LarryKazmerski, director of NREL’s National Centerfor Photovoltaics, “solar cells and modulesmust get much cheaper, get much more effi-cient, or both.” NREL and its research partnersin industry and universities are helping topush PV toward the cheaper and better alongseveral generations.

1st Generation—Silicon Wafers. This path isone of continuous incremental improvements.Silicon-wafer technology uses “thick” (150- to300-microns) wafers of crystalline silicon cellsconnected together to form modules andsandwiched between sheets of glass. In 2001,this mature technology constituted about 90%of the solar-cell market. Costs are dominatedby the relatively high cost of semiconductormaterial. Module conversion efficiencies areexpected to increase from today’s 13% to be-yond 16%. As a result of this and improve-ments in manufacturing technology, this path

could drop the cost of solar electricity toaround 7¢/kWh by 2010. This is

good for the short run, butnot as low as we can go in

the long term.

2nd Generation, Part 1—ThinFilms. This technology uses films

of semiconductor material that arefrom 1 to 10 microns thick. Hence,

thin films use far less semiconduc-tor material than does wafer silicon.

Thin-film devices can be made inunits as large as a meter—100 times as largeas a silicon wafer—and can be made in largeruns using mass-production techniques. Thinfilms are versatile and are leading the chargefor today’s specialty, building-integrated appli-cations. For example, thin-film modules canbe made translucent, as shingles for roofs, andincorporated into architectural glass.

NREL has been researching thin-film materialssince the late 1970s. Of these, three haveemerged—amorphous silicon, copper indiumdiselenide, and cadmium telluride. Amorphoussilicon has been building market share sincethe 1980s. The other two are relative new-comers to the market. Currently, the efficiencyof commercial thin-film modules ranges from5% to 11% (depending on the ma-terial and device structure), andcosts are competitive with those ofwafer silicon. But prospects arepromising. For example, by layer-ing thin-film materials on top ofeach other so that different layerscapture and convert different por-tions of the solar spectrum—aconcept known as “multijunc-tion”—modules could eventuallyconvert more than 15% of sunlightto electricity. This, along with im-proved production techniques,could drop electricity costs below4¢/kWh—competitive with mostconventional electricity, but withbuilt-in advantages.

2nd Generation, Part 2—Multi-junction. A third path is throughhigh-efficiency multijunction. Thisis similar to the thin-film multi-junction described above, exceptthat it relies on semiconductor ma-terials that could result in veryhigh efficiencies. These are materi-als primarily from Groups III and V

BP Solar’s new semi-transparent amorphoussilicon modules—devel-oped through participa-tion in the Amorphous

Silicon NationalResearch Team—are

used to provide powerto run pumps, lights,

and other loads at BPgasoline stations.

15

Nanorods and Quantum DotsNREL and its research partners have beeninvestigating semiconductor-related nano-technology since the early 1980s. In 1984,NREL researchers were among the first toreport on quantization effects in nanosizesemiconductor particles related to solarcells. Today, this pioneering research isshowing promising results in the form ofnanorod and quantum-dot solar cells.

Nanorods are semiconductor “wires” thatare a few nanometers wide and up to 100nanometers long (a nanometer is one-bil-lionth of a meter). Embedding nanorods inconductive plastic sheets results in thin,flexible solar cells. The nanorods absorblight of specific wavelengths to generateelectrons and holes (vacancies in the mate-rial that move around similar to electrons).The rods conduct the electrons along theirlength. Holes are transferred to the plastic,

whichconductsthem to an electrode.

Quantum dotsare dots of semi-conductor mate-rial containingfrom just a fewatoms to tens ofthousands ofatoms. Likenanorods, dotscan be embeddedin conductive polymer, or can be used withother materials, such as titanium dioxide. Byvarying their size, quantum dots can be tunedto absorb specific wavelengths of light and sorepresent an avenue toward multi-multijunc-tion devices that could theoretically convertas much as 66% of sunlight to electricity.

Two innovative organic solarcells: The top cell employsnanorods of cadmium seleni-um embedded in conductivepolymer. The bottom cell alsouses a conductive polymersubstrate, but with extremelythin embedded multilayers oforganic molecules.

The 4 Times Square building in Manhattan usesthin-film PV panels to supply 15 kW of power tosupplement the building’s electricity needs. Locatedon the top 14 floors on the south and east sides ofthe building, the PV panels are integrated into thespandrel—the opaque area of the façade belowrows of windows—in 60-inch-wide strips. (AndrewGordon Photography.)

NREL has built what maybe the world’s finest centerfor measuring and charac-terizing photovoltaic andrenewable energy materialsand devices. Shown hereare just a few of the dozensof sophisticated instrumentsused in the center: an XPS,for chemical-bonding infor-mation; a TOF SIMS, forsurface and compositionalanalysis; and an STM, fornanoscale imaging andspectroscopic studies.

of the Periodic Table of the Elements—such asgallium arsenide, indium phosphide, and gal-lium indium phosphide. Thus far, the best de-vice is a three-layer (three-junction) cell thatconverts up to 34% of sunlight to electricity(see sidebar “From Space to the Earth”).Typically, this approach uses concentratedsunlight, where lenses focus large amounts ofsolar energy onto a small cell.

3rd Generation—Beyond the Horizon. Todrastically lower the cost of solar electricity—below 2¢/kWh—you have to leapfrog theconventional to the innovative. This third gen-eration is mostly at the basic research stage,but these are concepts that auger very lowcost or very high efficiency (three or fourtimes that of current state-of-the-art silicon-wafer cells). The plastic cells mentionedabove are part of this future generation. Otherconcepts include:

• Hot-carrier solar cells (which capture andconvert electrons in excited states beforethey return to stable energy levels).

• Cells that can convert a photon into two ormore electron-hole pairs to carry the cur-rent, in contrast to conventional cells, inwhich a photon produces one electron-hole pair.

• Quantum-dot solar cells, in which nano-sized dots of semiconductor material aretuned to capture and convert specific wave-lengths of the solar spectrum (see sidebar“Nanorods and Quantum Dots”).

Concentrating Solar Power

Solar Troughs. When the federal research pro-gram began in the late 1970s, there were noconcentrating solar power systems in existence.By 1991, thousands of acres of solar troughs inthe Mojave Desert were generating 354 MW ofpower, thanks in large part to R&D by nationallaboratories (including NREL, along with SandiaNational Laboratories) and industry thatdropped costs three- to five-fold by 1990.

A solar trough uses parabolic-shaped mirrors toconcentrate sunlight onto a receiver (a heat-col-lection element) running along the focus of thecurved surface. For latitudes within the UnitedStates, the trough tracks the sun from east towest to maximize solar energy captured by thereceiver. This concentrated solar energy heatsoil flowing through the receiver, which is thenused to generate electricity via a conventionalsteam generator.

At 12¢ to 14¢/kWh, the troughs in the MojaveDesert produce electricity more cheaply thanother solar electric alternatives. As such, theyprovide supplementary power to a highly com-petitive market—that of peaking and intermedi-ate-load power for grid-scale applications.Moreover, with a federal R&D strategy that willhelp reduce the cost of electricity to about6¢/kWh by the end of the decade, solar troughswill be able to compete directly with conven-tional power generation for peaking markets.This strategy may also reduce trough electricityto less than 5¢/kWh by 2020, making it com-

petitive for central-station power. Toward theseends, R&D will focus on:

• A near-term capability to store solar energy forlong periods—such as in a molten salt medi-um—which would allow energy to be cap-tured while the sun shines and electricity to begenerated and dispatched while the sun is notshining. The ability to dispatch energy whenand where needed will extend the utility ofconcentrated solar power and reduce costs.

• Longer-term advanced fluids for thermal stor-age of solar energy—fluids whose propertieswould enable easy storage and retrieval ofenergy, at optimal working temperatures.

• Better, lighter, cheaper reflecting surfaces—such as very thin glass or flexible, high-densityaluminum—laminated on a flexible substrate.

• Improved heat-collection elements that captureand transfer solar energy more

efficiently.

The Perfect Dish. For greater modularity, onecan turn to dish concentrator systems, whichuse mirrors or reflective membranes in a dish-shaped configuration to reflect and focus thesun onto a small area, and a receiver/enginelocated at the focal point to generate electricity.When used with a Stirling heat engine to con-vert solar heat energy to electricity, a dish con-centrator can provide electricity in units thatrange in size from 3 kW to 25 kW.

Although today’s systems can convert nearly30% of sunlight to electricity and althoughR&D by NREL, Sandia National Laboratories,and industry has dropped costs and improvedreliability significantly since the early 1980s,the only systems in use today are those beingbuilt to test and demonstrate their viability. Butlarge markets are just around the corner.

Once we prove the ability of systems to operatereliably, economies of scale could reduce thecost of current designs to 8¢-10¢/kWh andopen the distributed generation market. R&D—especially that for developing a more reliable,efficient, and long-lasting engine system—willhelp drop costs even more.

Coming Full Circle. An innovative research di-rection combines the solar dish concentratorwith that of a highly efficient silicon or multi-junction PV module placed at the focal point ofthe concentrator. NREL researchers are engineer-ing the PV module so that it can withstand the

high concentration of solar energy at thefocal point. They are also redesigning theconcentrator concept, using a secondary

concentrator in tandem with the pri-mary dish concentrator. The sec-ondary concentrator alters theprofile of the concentrated

sunlight so that the so-lar flux will be

uniform acrossthe surface of themodule. If successful,this concept could make

the dish concentrator sys-tem more modular—reaching

units as small as 1 kW—andcould help reduce electricity cost

to 5¢/kWh, opening up the marketfor grid-connected substations.

For decades to come, satellites launchedinto Earth orbit will depend on power

provided by innovative solar cells pio-neered by NREL scientists and perfect-ed in partnership with industry. Thesedevices are lighter, more powerful,and more efficient than all previoussolar-cell power systems shot intospace. And more durable—they will

easily withstand 15 years of particlestorms sent by sun and solar wind.

The devices are double- and triple-junctioncells based on gallium indium phosphide,gallium arsenide, and germanium. Theyconvert about 30% of sunlight to electricity,far greater than other space solar cells.They’re not just good for space, though.NREL and Spectrolab—an industrial part-

ner—redesigned the cell for use on Earthunder concentrated sunlight. This Earth-bound version, which is especiallysuited for use under direct sunlight,can convert up to 34% of sunlightto electricity, a world record forphotovoltaics.

This research resulted in two presti-gious R&D 100 Awards—one for the spacecell and one for the redesign that brought itto Earth. But even more important, it hasled to breakthroughs in understanding sol-id-state materials, their growth processes,and their optical and electronic prop-erties. This understanding is leadingthe advance toward devices withfour and more junctions and efficienciesbeyond 40%.

Molecular beam epitaxy(MBE) is one of scores ofsystems NREL researchersuse to grow, develop, de-sign, and monitor PV cellsand devices. The MBE, infact, is integral to thegrowth and design ofNREL’s successful III-Vfamily of high-efficiencymultijunction devices.

The IMAGE (Imager forMagnetopause-to-

Aurora GlobalExploration) satellitewas one of the early

satellites to use thenew III-V multijunctioncells to provide powerfor operations. IMAGE

was launched in Marchof 2000 to study the

Earth’s magnetosphereand related phenome-na, such as the aurora

borealis. (Graphiccourtesy of NASA.)

The Impact 2000 home in Massachusetts uses a 4.5-kWutility-interactive PV system. It also incorporates many otherenergy efficiency and renewable energy features—solar hotwater, super insulation, passive solar heating and cooling,and an earth-coupled, geothermal heat pump.

16

From Space to the Earth

Ordered crystal structure of the gallium indium phos-phide material that is used in double- and triple-junctionhigh-efficiency solar cells.

of the Periodic Table of the Elements—such asgallium arsenide, indium phosphide, and gal-lium indium phosphide. Thus far, the best de-vice is a three-layer (three-junction) cell thatconverts up to 34% of sunlight to electricity(see sidebar “From Space to the Earth”).Typically, this approach uses concentratedsunlight, where lenses focus large amounts ofsolar energy onto a small cell.

3rd Generation—Beyond the Horizon. Todrastically lower the cost of solar electricity—below 2¢/kWh—you have to leapfrog theconventional to the innovative. This third gen-eration is mostly at the basic research stage,but these are concepts that auger very lowcost or very high efficiency (three or fourtimes that of current state-of-the-art silicon-wafer cells). The plastic cells mentionedabove are part of this future generation. Otherconcepts include:

• Hot-carrier solar cells (which capture andconvert electrons in excited states beforethey return to stable energy levels).

• Cells that can convert a photon into two ormore electron-hole pairs to carry the cur-rent, in contrast to conventional cells, inwhich a photon produces one electron-hole pair.

• Quantum-dot solar cells, in which nano-sized dots of semiconductor material aretuned to capture and convert specific wave-lengths of the solar spectrum (see sidebar“Nanorods and Quantum Dots”).

Concentrating Solar Power

Solar Troughs. When the federal research pro-gram began in the late 1970s, there were noconcentrating solar power systems in existence.By 1991, thousands of acres of solar troughs inthe Mojave Desert were generating 354 MW ofpower, thanks in large part to R&D by nationallaboratories (including NREL, along with SandiaNational Laboratories) and industry thatdropped costs three- to five-fold by 1990.

A solar trough uses parabolic-shaped mirrors toconcentrate sunlight onto a receiver (a heat-col-lection element) running along the focus of thecurved surface. For latitudes within the UnitedStates, the trough tracks the sun from east towest to maximize solar energy captured by thereceiver. This concentrated solar energy heatsoil flowing through the receiver, which is thenused to generate electricity via a conventionalsteam generator.

At 12¢ to 14¢/kWh, the troughs in the MojaveDesert produce electricity more cheaply thanother solar electric alternatives. As such, theyprovide supplementary power to a highly com-petitive market—that of peaking and intermedi-ate-load power for grid-scale applications.Moreover, with a federal R&D strategy that willhelp reduce the cost of electricity to about6¢/kWh by the end of the decade, solar troughswill be able to compete directly with conven-tional power generation for peaking markets.This strategy may also reduce trough electricityto less than 5¢/kWh by 2020, making it com-

petitive for central-station power. Toward theseends, R&D will focus on:

• A near-term capability to store solar energy forlong periods—such as in a molten salt medi-um—which would allow energy to be cap-tured while the sun shines and electricity to begenerated and dispatched while the sun is notshining. The ability to dispatch energy whenand where needed will extend the utility ofconcentrated solar power and reduce costs.

• Longer-term advanced fluids for thermal stor-age of solar energy—fluids whose propertieswould enable easy storage and retrieval ofenergy, at optimal working temperatures.

• Better, lighter, cheaper reflecting surfaces—such as very thin glass or flexible, high-densityaluminum—laminated on a flexible substrate.

• Improved heat-collection elements that captureand transfer solar energy more

efficiently.

The Perfect Dish. For greater modularity, onecan turn to dish concentrator systems, whichuse mirrors or reflective membranes in a dish-shaped configuration to reflect and focus thesun onto a small area, and a receiver/enginelocated at the focal point to generate electricity.When used with a Stirling heat engine to con-vert solar heat energy to electricity, a dish con-centrator can provide electricity in units thatrange in size from 3 kW to 25 kW.

Although today’s systems can convert nearly30% of sunlight to electricity and althoughR&D by NREL, Sandia National Laboratories,and industry has dropped costs and improvedreliability significantly since the early 1980s,the only systems in use today are those beingbuilt to test and demonstrate their viability. Butlarge markets are just around the corner.

Once we prove the ability of systems to operatereliably, economies of scale could reduce thecost of current designs to 8¢-10¢/kWh andopen the distributed generation market. R&D—especially that for developing a more reliable,efficient, and long-lasting engine system—willhelp drop costs even more.

Coming Full Circle. An innovative research di-rection combines the solar dish concentratorwith that of a highly efficient silicon or multi-junction PV module placed at the focal point ofthe concentrator. NREL researchers are engineer-ing the PV module so that it can withstand the

high concentration of solar energy at thefocal point. They are also redesigning theconcentrator concept, using a secondary

concentrator in tandem with the pri-mary dish concentrator. The sec-ondary concentrator alters theprofile of the concentrated

sunlight so that the so-lar flux will be

uniform acrossthe surface of themodule. If successful,this concept could make

the dish concentrator sys-tem more modular—reaching

units as small as 1 kW—andcould help reduce electricity cost

to 5¢/kWh, opening up the marketfor grid-connected substations.

For decades to come, satellites launchedinto Earth orbit will depend on power

provided by innovative solar cells pio-neered by NREL scientists and perfect-ed in partnership with industry. Thesedevices are lighter, more powerful,and more efficient than all previoussolar-cell power systems shot intospace. And more durable—they will

easily withstand 15 years of particlestorms sent by sun and solar wind.

The devices are double- and triple-junctioncells based on gallium indium phosphide,gallium arsenide, and germanium. Theyconvert about 30% of sunlight to electricity,far greater than other space solar cells.They’re not just good for space, though.NREL and Spectrolab—an industrial part-

ner—redesigned the cell for use on Earthunder concentrated sunlight. This Earth-bound version, which is especiallysuited for use under direct sunlight,can convert up to 34% of sunlightto electricity, a world record forphotovoltaics.

This research resulted in two presti-gious R&D 100 Awards—one for the spacecell and one for the redesign that brought itto Earth. But even more important, it hasled to breakthroughs in understanding sol-id-state materials, their growth processes,and their optical and electronic prop-erties. This understanding is leadingthe advance toward devices withfour and more junctions and efficienciesbeyond 40%.

Molecular beam epitaxy(MBE) is one of scores ofsystems NREL researchersuse to grow, develop, de-sign, and monitor PV cellsand devices. The MBE, infact, is integral to thegrowth and design ofNREL’s successful III-Vfamily of high-efficiencymultijunction devices.

The IMAGE (Imager forMagnetopause-to-

Aurora GlobalExploration) satellitewas one of the early

satellites to use thenew III-V multijunctioncells to provide powerfor operations. IMAGE

was launched in Marchof 2000 to study the

Earth’s magnetosphereand related phenome-na, such as the aurora

borealis. (Graphiccourtesy of NASA.)

The Impact 2000 home in Massachusetts uses a 4.5-kWutility-interactive PV system. It also incorporates many otherenergy efficiency and renewable energy features—solar hotwater, super insulation, passive solar heating and cooling,and an earth-coupled, geothermal heat pump.

17

From Space to the Earth

Ordered crystal structure of the gallium indium phos-phide material that is used in double- and triple-junctionhigh-efficiency solar cells.

What IS distributed energy resources, or DER? The termrefers to modular power generators that can be com-bined with energy management in storage to improvethe electricity delivery system. In the future, DER will

be the umbrella that connects exciting new tech-nologies—fuel cells, building-integrat-ed photovoltaics, and microturbines—together into power-generating pack-ages that are located at your businessor in your community. But, according

to Dick DeBlasio, NREL’s DER technology manager, “DERrefers as much to the way that people will relate to ener-gy—the way it will be distributed to your home, office, orschool—as to the way the electricity is generated.” DER isthe way electricity will work in the future, but it is also theway we’re going to make the transition to a more secureenergy future, where businesses, hospitals, and schools canstill operate even in emergencies and when the power gridis down.

Changing the Way We Grid

When you flip on a light at home today, electricity comes toyou from the power grid—a giant system of distribution andtransmission lines that radiate out from large power generationplants to send electricity to where we need it. Increasingly, as

DER is integrated into the system, these lineswill form two-way networks that, in turn, willcontain embedded distributed generators. In thesame way that computer technologies have

gone from mainframes to smaller computers net-worked together, the future power system will bedecentralized. Smaller “mini-grids” containingtheir own generators will be distributed through-out the larger system, closer to where the elec-tricity can be used.

These mini-grids can be as simple as one ortwo small generators feeding electricity toyour business or back to the power grid ifyou’re not using it. Or, they can be muchmore complicated—containing several typesof generators, such as fuel cells that converthydrogen into electricity, photovoltaics, orwind turbines, along with biomass or fossil-fuel generators for backup and energy stor-age systems—all networked together andcontrolled by computers that manage thepower systems.

According to Tony Schaffhauser, NREL’s DERcenter director, DER is really about flexibilityand choice. “DER provides people with agreater choice of sources, including more con-trol over what environmental effects the elec-tricity they use will have,” he says.

Making Power ReliableDER is about flexibility and choice—and more.Moving toward an electricity model based onintegrating distributed energy resources into theenergy infrastructure has a variety of benefits.For one thing, having many power generatorsconnected to a grid in a distributed fashioncould greatly increase reliability—with a smart,well-designed distributed energy network,power would always be available (or at least99.99999% of the time). Blackouts (which arecaused primarily by failures in distributionlines) and rolling brownouts may even becomea thing of the past.

Second, the quality of the power provided hasa potential to become much better and morestable. As a result, there would be far fewervoltage surges, spikes, and sags. This could beimportant to the modern business community,much of which is run by digital technologyand is very sensitive to variations in power

Distributed energy resources doesnot just refer to distributed genera-tion of power. It also refers to thefact that much of the natural re-sources that can be used to providethe energy that generates the elec-tricity also is distributed. This in-cludes wind energy, geothermalenergy, hydropower, biomass, andsunshine (or solar radiation). Inmaking decisions on where orwhether to locate a generator de-pendent on these resources, it is im-portant to know their spatialdistribution, intensity, availability,and other characteristics. NREL sci-entists have long been modeling,measuring, and characterizing theseresources. In particular, throughoutits existence, NREL has steadilybuilt a world-renowned reputationfor its research in solar radiation, es-pecially in measuring and modelingthis resource.

At the center of this reputation isNREL’s Solar Radiation ResearchLaboratory. This unique research fa-cility continually measures andmonitors solar radiation and othermeteorological data and dissemi-nates the information to government,

industry, academic, and internationallaboratories and agencies. The datathat the laboratory measures in-cludes global, diffuse, and direct-normal irradiance, ultravioletradiation, infrared radiation from theEarth’s surface, atmospheric aerosols,wind speed and direction, tempera-ture, barometric pressure, relativehumidity, and more. These data maynot only be used for testing systemsthat convert solar energy to electrici-ty, but also for climate-change stud-ies, for research on weather and theatmosphere, and more.

The Distributed Resource

A researcher adjusts an absolute cavity ra-diometer at NREL’s Solar Radiation ResearchLaboratory. Absolute cavity radiometers areused to make very accurate measurements ofsolar irradiance and provide the referencefrom which other radiometers are calibrated.

In the future, distributedenergy resources will bethe way energy works––connecting exciting newtechnologies into power-generating packages lo-

cated at your business orin your community. In

addition to central powerplants, distributed energy

means that a variety ofelectricity sources are

distributed close towhere they will be used,

allowing for more effi-cient use of heat that is

“wasted” at power plantstoday. It also provides

greater security, spread-ing out sources of elec-

tricity so that operationscan continue even if onesource is not operational.

18

What IS distributed energy resources, or DER? The termrefers to modular power generators that can be com-bined with energy management in storage to improvethe electricity delivery system. In the future, DER will

be the umbrella that connects exciting new tech-nologies—fuel cells, building-integrat-ed photovoltaics, and microturbines—together into power-generating pack-ages that are located at your businessor in your community. But, according

to Dick DeBlasio, NREL’s DER technology manager, “DERrefers as much to the way that people will relate to ener-gy—the way it will be distributed to your home, office, orschool—as to the way the electricity is generated.” DER isthe way electricity will work in the future, but it is also theway we’re going to make the transition to a more secureenergy future, where businesses, hospitals, and schools canstill operate even in emergencies and when the power gridis down.

Changing the Way We Grid

When you flip on a light at home today, electricity comes toyou from the power grid—a giant system of distribution andtransmission lines that radiate out from large power generationplants to send electricity to where we need it. Increasingly, as

DER is integrated into the system, these lineswill form two-way networks that, in turn, willcontain embedded distributed generators. In thesame way that computer technologies have

gone from mainframes to smaller computers net-worked together, the future power system will bedecentralized. Smaller “mini-grids” containingtheir own generators will be distributed through-out the larger system, closer to where the elec-tricity can be used.

These mini-grids can be as simple as one ortwo small generators feeding electricity toyour business or back to the power grid ifyou’re not using it. Or, they can be muchmore complicated—containing several typesof generators, such as fuel cells that converthydrogen into electricity, photovoltaics, orwind turbines, along with biomass or fossil-fuel generators for backup and energy stor-age systems—all networked together andcontrolled by computers that manage thepower systems.

According to Tony Schaffhauser, NREL’s DERcenter director, DER is really about flexibilityand choice. “DER provides people with agreater choice of sources, including more con-trol over what environmental effects the elec-tricity they use will have,” he says.

Making Power ReliableDER is about flexibility and choice—and more.Moving toward an electricity model based onintegrating distributed energy resources into theenergy infrastructure has a variety of benefits.For one thing, having many power generatorsconnected to a grid in a distributed fashioncould greatly increase reliability—with a smart,well-designed distributed energy network,power would always be available (or at least99.99999% of the time). Blackouts (which arecaused primarily by failures in distributionlines) and rolling brownouts may even becomea thing of the past.

Second, the quality of the power provided hasa potential to become much better and morestable. As a result, there would be far fewervoltage surges, spikes, and sags. This could beimportant to the modern business community,much of which is run by digital technologyand is very sensitive to variations in power

Distributed energy resources doesnot just refer to distributed genera-tion of power. It also refers to thefact that much of the natural re-sources that can be used to providethe energy that generates the elec-tricity also is distributed. This in-cludes wind energy, geothermalenergy, hydropower, biomass, andsunshine (or solar radiation). Inmaking decisions on where orwhether to locate a generator de-pendent on these resources, it is im-portant to know their spatialdistribution, intensity, availability,and other characteristics. NREL sci-entists have long been modeling,measuring, and characterizing theseresources. In particular, throughoutits existence, NREL has steadilybuilt a world-renowned reputationfor its research in solar radiation, es-pecially in measuring and modelingthis resource.

At the center of this reputation isNREL’s Solar Radiation ResearchLaboratory. This unique research fa-cility continually measures andmonitors solar radiation and othermeteorological data and dissemi-nates the information to government,

industry, academic, and internationallaboratories and agencies. The datathat the laboratory measures in-cludes global, diffuse, and direct-normal irradiance, ultravioletradiation, infrared radiation from theEarth’s surface, atmospheric aerosols,wind speed and direction, tempera-ture, barometric pressure, relativehumidity, and more. These data maynot only be used for testing systemsthat convert solar energy to electrici-ty, but also for climate-change stud-ies, for research on weather and theatmosphere, and more.

The Distributed Resource

A researcher adjusts an absolute cavity ra-diometer at NREL’s Solar Radiation ResearchLaboratory. Absolute cavity radiometers areused to make very accurate measurements ofsolar irradiance and provide the referencefrom which other radiometers are calibrated.

In the future, distributedenergy resources will bethe way energy works––connecting exciting newtechnologies into power-generating packages lo-

cated at your business orin your community. In

addition to central powerplants, distributed energy

means that a variety ofelectricity sources are

distributed close towhere they will be used,

allowing for more effi-cient use of heat that is

“wasted” at power plantstoday. It also provides

greater security, spread-ing out sources of elec-

tricity so that operationscan continue even if onesource is not operational.

19

quality. In fact, the Electric Power ResearchInstitute estimates that power outages andpoor power quality cost American businessesmore than $100 billion each year.

Third, there is greater energy security in a gridnetwork in which many generators are provid-ing the electricity. If all of a region’s electricityis supplied by one central power facility, forexample, and that facility goes down—whether by natural means or through sabo-tage—then the entire region will be shutdown. This would not happen with awell-designed distributed energy net-work, which provides inherentredundancy and safety.

DER also benefits utilities. A network that de-pends on a wide variety of mini- and micro-generators can add capacity incrementally,when and where it is needed.Such a network can avoid theexpensive financial and timecommitment demanded by theconstruction of large, central facilities.

Using All the Heat

But efficiency may be the most compelling ar-gument for distributed energy resources.Traditional power generation plants burn coal

or gas. But only aboutone-third of the pri-

mary energy usedis captured andconverted to elec-tricity. Then, asmuch as another10% can be lostthrough transmis-sion and distribu-tion of theelectricity. Sincethe point of DER,on the otherhand, is to gener-ate electricityclose to where itis to be used, youcan minimizelosses due totransmission ordistribution. Plus,heat that is tradi-tionally “wasted”can be convertedto power in otherways. Using

waste heat efficiently, a micro-grid at yourhome will power your appliances; heat, cool,and adjust humidity levels in your home; andheat your water. In industrial settings, wasteheat will power industrial processes.

Researchers are working on additional andmore effective ways to use that waste heat andmake power generation more effective. As wefind ways to be more efficient, as much as60% of the power used to generate electricitywill be captured.

Making the Rules

As the brave new world of creating our ownelectricity evolves, we need to think strategi-cally about the rules that will govern its use.Like codes and standards governing the waybuildings are made or commerce is conduct-ed, standards for the way that people canconnect into the power grid, how they cansend electricity back to the grid, and rulesgoverning the way that utilities relate to thesemini-grids are critical. Right now, businessesthat install photovoltaic systems and try to tiein to the power grid face different procedureswith different utilities, and states and localgovernments also have different rules.

Navigating the process can be frus-trating and lengthy.

But for two years now, a national group ofalmost 300 members of the Institute of

Electrical and Electronics Engineers (IEEE)—representatives from utilities, electricity pro-ducers, manufacturers, laboratories, andconsulting groups—have been developingtechnical standards to make the process more

consistent. NREL’s Dick DeBlasio, chair ofthe IEEE working group, saysthat once the group has ap-proved the standards, stateand federal regulators willhave the option of adoptingthem. “Right now there arehundreds, if not thousands, ofutility rules for connecting tothe grid,” he says. “Thestandards we are develop-ing will, as they are adopt-

ed by utilities and regulatorycommissions, level the playing field

for distributed resources and enable them tocompete in the marketplace.”

At the same time, from the regulatory perspec-tive, state and local governments are also tryingto address the challenges of bringing about adistributed energy generation future. GaryNakarado, NREL’s DER regulatory liaison, isworking with regulators to make changes in theway that regulations are structured—moving toa different model that can accommodate more

customer choice and more power providers.“The traditional regulatory model is turned onits head by distributed generation,” Nakaradosays. “We need to encourage policy makers toask the important questions, like ‘What’s in thepublic interest?’ because there are so many newtools and technologies available.”

Pulling It All Together

The full integration of renewable energy re-sources and distributed generation into thenation’s energy infrastructure will be a long-term process that will involve research, tech-nology, negotiations, and cooperation onmany levels across the United States. Butsuch an integration will liberate our depend-ence on traditional fuel sources. And it willprovide a reliable, secure, and flexible systemof powering America.

The Distributed Energy ResourcesTest Facility looks like a mass ofelectric switches, panels, andlines connecting large machinestogether. That’s exactly what itis—the facility, which is the onlyone of its kind, tests how distrib-uted generation sources connectand work together.

At the facility, generation sourcessuch as a 30-kW microturbine,60- or 100-kW wind turbines, vari-ous-sized diesel generators, and a1.8-kW photovoltaics panel areconnected to a 200-kW “grid”—simulating a utility. This allows re-searchers to test how each of thesources work together and howthey interact.

A lightning-surge simulator testswhat happens to the individualsources and the whole systemduring adverse weather condi-tions, and the grid can also beturned off to simulate emergencysituations when the electric grid isdown. Grid-simulator controls al-low researchers to adjust the volt-age and frequency of electricitymoving in the grid to simulatesags and surges on the distributionsystem—similar to variations inthe real power grid and distribu-

tion systems that result in black-outs or brownouts. Using an elec-tric-load simulator, researcherscan see how the systems work un-der different use patterns—up to165 kW of load.

This kind of work requires a high-speed data acquisition system—andthe facility has one that samples at5 million samples per second.Collecting data that quickly allowsresearchers to monitor high-speedinterconnections between the gen-eration sources and to record elec-trical faults and disturbances.

The test facility will help determinehow reliable distributed power sys-tems are, provide research data touse when developing interconnec-tion standards, and help understandhow complex energy systems canbe integrated together. Researcherscan evaluate moment-by-momentdynamics of distributed power sys-tems, gather data on long-term per-formance, and demonstrate newdesign concepts.

A new, larger, energy-efficient testfacility is under design and is ex-pected to open by 2005. The10,000-square-foot facility will in-crease testing capacity to up to1 MW of generation.

Electricity Soup

Microturbines are represen-tative of just one of the many

kinds of distributed powergenerators that are ideal for

use in a distributed network.Microturbines, which can be

powered by natural gas orbiofuels, provide a reliable

source of electricity and heatfor commercial businesses

and industries.

A researcher monitors the control panel for a simulated utilitygrid at NREL’s Distributed Energy Resources Test Facility.Using the control panel, researchers can adjust voltage, fre-quencies, loads, and a variety of other parameters to deter-mine how the network may work under different conditions.

20

This stand-alone system creates a mini-grid whereverit goes and creates enough power to run asmall home. It consists of a 1.8-kilowattphotovoltaic panel, a diesel gener-ator for backup, and invert-ers to convert directcurrent power toalternatingcurrent.

quality. In fact, the Electric Power ResearchInstitute estimates that power outages andpoor power quality cost American businessesmore than $100 billion each year.

Third, there is greater energy security in a gridnetwork in which many generators are provid-ing the electricity. If all of a region’s electricityis supplied by one central power facility, forexample, and that facility goes down—whether by natural means or through sabo-tage—then the entire region will be shutdown. This would not happen with awell-designed distributed energy net-work, which provides inherentredundancy and safety.

DER also benefits utilities. A network that de-pends on a wide variety of mini- and micro-generators can add capacity incrementally,when and where it is needed.Such a network can avoid theexpensive financial and timecommitment demanded by theconstruction of large, central facilities.

Using All the Heat

But efficiency may be the most compelling ar-gument for distributed energy resources.Traditional power generation plants burn coal

or gas. But only aboutone-third of the pri-

mary energy usedis captured andconverted to elec-tricity. Then, asmuch as another10% can be lostthrough transmis-sion and distribu-tion of theelectricity. Sincethe point of DER,on the otherhand, is to gener-ate electricityclose to where itis to be used, youcan minimizelosses due totransmission ordistribution. Plus,heat that is tradi-tionally “wasted”can be convertedto power in otherways. Using

waste heat efficiently, a micro-grid at yourhome will power your appliances; heat, cool,and adjust humidity levels in your home; andheat your water. In industrial settings, wasteheat will power industrial processes.

Researchers are working on additional andmore effective ways to use that waste heat andmake power generation more effective. As wefind ways to be more efficient, as much as60% of the power used to generate electricitywill be captured.

Making the Rules

As the brave new world of creating our ownelectricity evolves, we need to think strategi-cally about the rules that will govern its use.Like codes and standards governing the waybuildings are made or commerce is conduct-ed, standards for the way that people canconnect into the power grid, how they cansend electricity back to the grid, and rulesgoverning the way that utilities relate to thesemini-grids are critical. Right now, businessesthat install photovoltaic systems and try to tiein to the power grid face different procedureswith different utilities, and states and localgovernments also have different rules.

Navigating the process can be frus-trating and lengthy.

But for two years now, a national group ofalmost 300 members of the Institute of

Electrical and Electronics Engineers (IEEE)—representatives from utilities, electricity pro-ducers, manufacturers, laboratories, andconsulting groups—have been developingtechnical standards to make the process more

consistent. NREL’s Dick DeBlasio, chair ofthe IEEE working group, saysthat once the group has ap-proved the standards, stateand federal regulators willhave the option of adoptingthem. “Right now there arehundreds, if not thousands, ofutility rules for connecting tothe grid,” he says. “Thestandards we are develop-ing will, as they are adopt-

ed by utilities and regulatorycommissions, level the playing field

for distributed resources and enable them tocompete in the marketplace.”

At the same time, from the regulatory perspec-tive, state and local governments are also tryingto address the challenges of bringing about adistributed energy generation future. GaryNakarado, NREL’s DER regulatory liaison, isworking with regulators to make changes in theway that regulations are structured—moving toa different model that can accommodate more

customer choice and more power providers.“The traditional regulatory model is turned onits head by distributed generation,” Nakaradosays. “We need to encourage policy makers toask the important questions, like ‘What’s in thepublic interest?’ because there are so many newtools and technologies available.”

Pulling It All Together

The full integration of renewable energy re-sources and distributed generation into thenation’s energy infrastructure will be a long-term process that will involve research, tech-nology, negotiations, and cooperation onmany levels across the United States. Butsuch an integration will liberate our depend-ence on traditional fuel sources. And it willprovide a reliable, secure, and flexible systemof powering America.

The Distributed Energy ResourcesTest Facility looks like a mass ofelectric switches, panels, andlines connecting large machinestogether. That’s exactly what itis—the facility, which is the onlyone of its kind, tests how distrib-uted generation sources connectand work together.

At the facility, generation sourcessuch as a 30-kW microturbine,60- or 100-kW wind turbines, vari-ous-sized diesel generators, and a1.8-kW photovoltaics panel areconnected to a 200-kW “grid”—simulating a utility. This allows re-searchers to test how each of thesources work together and howthey interact.

A lightning-surge simulator testswhat happens to the individualsources and the whole systemduring adverse weather condi-tions, and the grid can also beturned off to simulate emergencysituations when the electric grid isdown. Grid-simulator controls al-low researchers to adjust the volt-age and frequency of electricitymoving in the grid to simulatesags and surges on the distributionsystem—similar to variations inthe real power grid and distribu-

tion systems that result in black-outs or brownouts. Using an elec-tric-load simulator, researcherscan see how the systems work un-der different use patterns—up to165 kW of load.

This kind of work requires a high-speed data acquisition system—andthe facility has one that samples at5 million samples per second.Collecting data that quickly allowsresearchers to monitor high-speedinterconnections between the gen-eration sources and to record elec-trical faults and disturbances.

The test facility will help determinehow reliable distributed power sys-tems are, provide research data touse when developing interconnec-tion standards, and help understandhow complex energy systems canbe integrated together. Researcherscan evaluate moment-by-momentdynamics of distributed power sys-tems, gather data on long-term per-formance, and demonstrate newdesign concepts.

A new, larger, energy-efficient testfacility is under design and is ex-pected to open by 2005. The10,000-square-foot facility will in-crease testing capacity to up to1 MW of generation.

Electricity Soup

Microturbines are represen-tative of just one of the many

kinds of distributed powergenerators that are ideal for

use in a distributed network.Microturbines, which can be

powered by natural gas orbiofuels, provide a reliable

source of electricity and heatfor commercial businesses

and industries.

A researcher monitors the control panel for a simulated utilitygrid at NREL’s Distributed Energy Resources Test Facility.Using the control panel, researchers can adjust voltage, fre-quencies, loads, and a variety of other parameters to deter-mine how the network may work under different conditions.

21

What if your house were a mini-powerplant, generating the power you need tolive? Imagine—solar panels in the form of

roof shingles, heat-col-lecting walls, and fuelcells powering yourappliances, heatingyour home, and evencharging your car. Andbuildings of the futurewill be “smarter,” withwindows that automati-

cally darken to shade duringthe heat of summer and open or close to allownatural ventilation. Computer systems will auto-matically control lighting levels and turn on andoff your appliances. All of these technologiesand concepts will make the buildings of the fu-ture more productive and comfortable, extreme-ly energy efficient, and secure—continuing torun even if the electric grid is down.

Living Laboratories

We might be further along the path to this futurethan you realize. Researchers are testing homeand office designs today that are up to 80% moreenergy efficient than those built when NREL firstbegan operating. These new building designscombine renewable and energy-efficient tech-nologies in ways we could not have imagined in

past decades.

In fact, much of the focus in improving build-ings today is taking knowledge gained in pastresearch into the real world to test it there.These real-world test sites, or living laborato-

ries, use technologies and research results fromindustry (as well as from laboratories) and look atthem as a whole system—testing how all theseparate pieces are functioning together. Moreimportant, living laboratories show how the vari-ous systems in the whole building can be moreefficient and cost effective.

NREL’s work in both the commercial buildingsector—schools, office buildings, and retail build-ings—and the residential sector—single familyhomes, apartment buildings, and housing com-munities—helps move both markets forward byacting as a way for manufacturers, builders, anddesigners to find out how their products andtechnologies can be more effective.

Changing the Way We Work and Shop

In the mountains of Colorado, the BigHornRetail Complex in Silverthorne is one of the na-tion’s first retail buildings to use natural daylightand ventilation cooling. The complex is de-signed to allow light into the building withoutcreating too much heat, and because of carefuldesign, no air-conditioning system is needed.A photovoltaic system integrated into the roof,along with energy-efficient features like a solarmass wall and compact fluorescent light fixtures,has reduced energy use by more than 60%.

BigHorn is one of many living laboratories test-ing the most advanced building technologies inthe world. “Scientists have spent the last twodecades measuring energy in buildings and find-ing out which technologies, by themselves, aremost efficient,” says High-PerformanceBuildings Task Leader Paul Torcellini. “Now,” hesays, “it’s time to design a decision-makingprocess to consider all the parts as a system.”

“Designing efficient buildings is a process—based on hard science—that helps us build com-mercial buildings that are more environmentallysensitive and comfortable,” Torcellini says. “Inthis stage of research, we’re trying to weigh thebenefits of different building features, instead ofjust testing windows or photovoltaic systems.”

Changing the Way We Learn

In addition to being a living laboratory, whereresearchers hone energy efficiency and designtechnologies, Oberlin College’s Center forEnvironmental Studies is a living classroom forstudents, where the building itself is the main top-ic of study. The building’s wastewater is treatedusing a system of microbes, plants, snails, and in-sects. A solar electric system on the main south-

In the Sonoran Desert aroundTucson, Arizona, the Civano com-munity members are trying a newway of coexisting with the envi-

ronment and each other. The820-acre neighborhood

development was de-signed to pro-

moteeconomicgrowth

while focus-ing on social

values and eco-logical harmony. Thecommunity supportshousing, as well as lightindustry and commer-cial and retail business-es located no more thana 5-minute walk fromthe homes. Anothergoal of the communityis to minimize the useof natural resourcessubstantially below pre-

vailing levels in comparable devel-opments, in part by using renewableenergy and creating building de-signs that are energy efficient—allthe homes in Civano use less than50% of the energy of a convention-ally built home and all have solarwater heaters. NREL’s researchershave been monitoring the efficiencyof Civano’s homes, collecting dataand creating virtual models of thebuildings on computer to under-stand how energy is being used andhow to improve performance.

22 23

Living Desert Wise

Even high in the Colorado moun-tains, where winter temperaturescause heating challenges for anybuilding, BigHorn’s large, retailspaces and warehouse are con-suming 62% less energy than asimilar, conventional space.NREL’s researchers helped to de-sign and test, and continue tomonitor the complex, which is

breaking ground for the future ofretail space with a lot of “firsts.”The complex is one of the first re-tail buildings in the United Statesto use daylighting and natural ven-tilation cooling systems, the largestcommercial photovoltaic array inColorado (9-kW capacity), thestate’s first commercial buildingto have a standing-seam, roof-integrated PV system, and thefirst retail center in Coloradoto have a net metering agree-ment (where electricity pro-duced over the amount used issold back to the utility). Insidethe building, customers experi-ence radiant floor heating, andlarge, operable windows that letin Colorado’s bright sun and lookout on the Rocky Mountains. Acomputer system automaticallybalances the ventilation and light-ing levels to make sure customershave the optimum comfort levelsfor shopping.

The BigHorn high-performance building features PV,clerestory windows, daylighting, diffusing skylights,

and solar wall. Anticipated energy cost savings fromall the features, not including PV, is 62%.

Shopping Mile High

Each home at the Civano developmentincorporates results of systems engineer-ing developed by teams under theBuilding America program.

What if your house were a mini-powerplant, generating the power you need tolive? Imagine—solar panels in the form of

roof shingles, heat-col-lecting walls, and fuelcells powering yourappliances, heatingyour home, and evencharging your car. Andbuildings of the futurewill be “smarter,” withwindows that automati-

cally darken to shade duringthe heat of summer and open or close to allownatural ventilation. Computer systems will auto-matically control lighting levels and turn on andoff your appliances. All of these technologiesand concepts will make the buildings of the fu-ture more productive and comfortable, extreme-ly energy efficient, and secure—continuing torun even if the electric grid is down.

Living Laboratories

We might be further along the path to this futurethan you realize. Researchers are testing homeand office designs today that are up to 80% moreenergy efficient than those built when NREL firstbegan operating. These new building designscombine renewable and energy-efficient tech-nologies in ways we could not have imagined in

past decades.

In fact, much of the focus in improving build-ings today is taking knowledge gained in pastresearch into the real world to test it there.These real-world test sites, or living laborato-

ries, use technologies and research results fromindustry (as well as from laboratories) and look atthem as a whole system—testing how all theseparate pieces are functioning together. Moreimportant, living laboratories show how the vari-ous systems in the whole building can be moreefficient and cost effective.

NREL’s work in both the commercial buildingsector—schools, office buildings, and retail build-ings—and the residential sector—single familyhomes, apartment buildings, and housing com-munities—helps move both markets forward byacting as a way for manufacturers, builders, anddesigners to find out how their products andtechnologies can be more effective.

Changing the Way We Work and Shop

In the mountains of Colorado, the BigHornRetail Complex in Silverthorne is one of the na-tion’s first retail buildings to use natural daylightand ventilation cooling. The complex is de-signed to allow light into the building withoutcreating too much heat, and because of carefuldesign, no air-conditioning system is needed.A photovoltaic system integrated into the roof,along with energy-efficient features like a solarmass wall and compact fluorescent light fixtures,has reduced energy use by more than 60%.

BigHorn is one of many living laboratories test-ing the most advanced building technologies inthe world. “Scientists have spent the last twodecades measuring energy in buildings and find-ing out which technologies, by themselves, aremost efficient,” says High-PerformanceBuildings Task Leader Paul Torcellini. “Now,” hesays, “it’s time to design a decision-makingprocess to consider all the parts as a system.”

“Designing efficient buildings is a process—based on hard science—that helps us build com-mercial buildings that are more environmentallysensitive and comfortable,” Torcellini says. “Inthis stage of research, we’re trying to weigh thebenefits of different building features, instead ofjust testing windows or photovoltaic systems.”

Changing the Way We Learn

In addition to being a living laboratory, whereresearchers hone energy efficiency and designtechnologies, Oberlin College’s Center forEnvironmental Studies is a living classroom forstudents, where the building itself is the main top-ic of study. The building’s wastewater is treatedusing a system of microbes, plants, snails, and in-sects. A solar electric system on the main south-

In the Sonoran Desert aroundTucson, Arizona, the Civano com-munity members are trying a newway of coexisting with the envi-

ronment and each other. The820-acre neighborhood

development was de-signed to pro-

moteeconomicgrowth

while focus-ing on social

values and eco-logical harmony. Thecommunity supportshousing, as well as lightindustry and commer-cial and retail business-es located no more thana 5-minute walk fromthe homes. Anothergoal of the communityis to minimize the useof natural resourcessubstantially below pre-

vailing levels in comparable devel-opments, in part by using renewableenergy and creating building de-signs that are energy efficient—allthe homes in Civano use less than50% of the energy of a convention-ally built home and all have solarwater heaters. NREL’s researchershave been monitoring the efficiencyof Civano’s homes, collecting dataand creating virtual models of thebuildings on computer to under-stand how energy is being used andhow to improve performance.

The pool of the Civano developmentin Tucson, Arizona, uses a 6-kW pho-tovoltaic installation to help meet the

community’s energy standard.

23

Living Desert Wise

Even high in the Colorado moun-tains, where winter temperaturescause heating challenges for anybuilding, BigHorn’s large, retailspaces and warehouse are con-suming 62% less energy than asimilar, conventional space.NREL’s researchers helped to de-sign and test, and continue tomonitor the complex, which is

breaking ground for the future ofretail space with a lot of “firsts.”The complex is one of the first re-tail buildings in the United Statesto use daylighting and natural ven-tilation cooling systems, the largestcommercial photovoltaic array inColorado (9-kW capacity), thestate’s first commercial buildingto have a standing-seam, roof-integrated PV system, and thefirst retail center in Coloradoto have a net metering agree-ment (where electricity pro-duced over the amount used issold back to the utility). Insidethe building, customers experi-ence radiant floor heating, andlarge, operable windows that letin Colorado’s bright sun and lookout on the Rocky Mountains. Acomputer system automaticallybalances the ventilation and light-ing levels to make sure customershave the optimum comfort levelsfor shopping.

The BigHorn high-performance building features PV,clerestory windows, daylighting, diffusing skylights,

and solar wall. Anticipated energy cost savings fromall the features, not including PV, is 62%.

Shopping Mile High

Each home at the Civano developmentincorporates results of systems engineer-ing developed by teams under theBuilding America program.

facing curved roof provides half of the electricalenergy for the building. Overhanging eaves andtrusses shade the summer sun while allowingwinter heat gain. Natural light comes into thebuilding through clerestories and south-facingwindows, reducing the need for electrical lighting.

At the center, electronic sensors track light in-tensity, electricity produced by the solar electricpanels, and energy consumed by the heatingand ventilation systems. A monitoring systemhelps students and NREL researchers understandhow a building interacts with its environmentand how it behaves as a system.

In many schools, students and researchers alikelearn about energy efficiency and renewabletechnologies through partnerships—like theone with Oberlin—and programs like DOE’sEnergySmart Schools. NREL’s EnergySmartSchools Coordinator Patricia Plympton saysthat these programs are transitioning ourschools to new ways of using and teachingabout energy. “Sometimes students can teachus how to make classrooms more comfortableand productive using energy efficiency and re-newable technologies,” she says. “We’re alllearning from these living laboratories.”

Changing the Way We Live

In the desert community of Civano, outsideTucson, Arizona, all homes use 50% less energy

than a traditional home. The sun is used to heatwater for swimming pools and homes, and pho-tovoltaics help to offset electricity consumption.A network of bike and walking paths connectoffice buildings with homes to reduce the needfor driving. Native landscaping and efficientbuilding materials help the community livewithin the desert ecosystem, reducing waterconsumption and the need for air-conditioning.

Research on communities like Civano is help-ing scientists measure the effectiveness oftechnologies and improve designs. Energy per-formance is monitored and put into a comput-er system to model ways to make the homeseven more efficient. This huge network of liv-ing laboratories is a catalyst for change in thehome-building industry. Many large buildersare starting to see the benefits of producinghomes on a community scale that use 30% to50% less energy, reduceconstruction time andwaste by as muchas 50%, andprovide newproduct op-portunities tomanufacturers.

“We work with buildersand designers, who arechanging the way homes arebuilt,” said Paul Norton, NRELproject manager for DOE’sBuilding America program. “Our

research develops and refines technologies tomeet the builders’ specific needs, and also totest performance to find solutions when thingsdon’t work the way we thought they would.”

Getting to Zero—Buildings thatProduce Energy

Compared to the off-grid, energy self-sufficientEarthships of the 1970s, the Solar Patriot houseoutside of Washington, D.C., is a space station.Many people have built homes that are self-sus-taining, but the Solar Patriot house represents thefirst mass-market house that is connected to apower grid but not dependent on it. The houseuses a photovoltaic system to generate electrici-ty, aided by a solar hot-water system and passivesolar design, which has been so successful that ithas produced enough excess electricity to con-

sistently spin its electric meterbackward.

Tim Merrigan, NREL project manager for thenew DOE initiative for zero-energy homes, saysthat the Solar Patriot house is just one of themany zero-energy homes that will be tested dur-ing the next few years. NREL has awarded con-tracts to four teams of builders this past year todevelop new kinds of designs for homes.

“Most people can’t buy a zero-energy home to-day, but what does exist is a vast amount ofknowledge that will make zero-energy homesavailable to everyone in the future—buildingtechnology research as well as long-term fieldtesting of solar hot-water systems and photo-voltaic systems,” Merrigan said. “All that re-search exists and this program brings thatresearch together. The Zero Energy Buildingsprogram has very lofty goals, and we’re on thebrink of meeting those goals.”

What if your house were a mini-power plant,your roof shingles were photovoltaic panels, andheat collecting walls heated your home? Thesetechnologies already exist today, and are alreadybeing used in living laboratories across the nationto hone them for efficient, large-scale use in themarketplace. It may sound futuristic, but build-ings technologies like these are not far away.

Installation of PV-integrated standing-seam metal roof panels.

24 25

For eight days in 2002, 14 studentteams will participate in a compe-tition that will be a living laborato-ry for future designers, engineers,researchers, and communicators.The student teams will compete tocapture, convert, store, and useenough solar energy to power a“home” they will build themselves

on the Washington, DC, mall.Solar Decathletes will be requiredto provide all the energy for anentire household, including ahome-based business and thetransportation needs of the house-hold and business. During theevent, only the solar energy avail-able within the perimeter of eachhouse may be used to generate thepower needed to compete in theten Solar Decathlon contests. TheSolar Decathlon, sponsored byDOE and administered by NREL,will educate consumers about so-lar energy and energy-efficientproducts and also guide the nextgeneration of researchers, ar-chitects, engineers, andbuilders as they prepare tobegin their careers.

Competing for the Future

In a serene neighborhood just out-side Washington, D.C., the SolarPatriot house is quietly heralding thenext step in the transition to build-ings of the future. The house is soefficient that its 6-kW photovoltaicsystem produced more electricitythan the family used during 2-1/2months in early fall 2001. Also dur-ing that time, the house remainedfully powered, while the rest of theneighborhood went dark duringeight power outages. In addition, thefive-bedroom house is not only af-fordable for its rapidly growing areaof the country, but its exterior needs

no more maintenance than a con-ventional home. The standing-seammetal roof has a life expectancy of40-50 years. Maintenance on the so-lar systems is minimal.

A Future of Zero Energy

The “Solar Patriot,” in Virginia has a 6-kW PVsystem, solar water heater, geothermal heatpump, compact fluorescent lighting, high-efficiency appliances,and low-e windows.

The 2002 Solar Decathlon team from theUniversity of Colorado at Boulder developed thedesign of their house in a collaborative effort be-tween engineering and architecture students.

facing curved roof provides half of the electricalenergy for the building. Overhanging eaves andtrusses shade the summer sun while allowingwinter heat gain. Natural light comes into thebuilding through clerestories and south-facingwindows, reducing the need for electrical lighting.

At the center, electronic sensors track light in-tensity, electricity produced by the solar electricpanels, and energy consumed by the heatingand ventilation systems. A monitoring systemhelps students and NREL researchers understandhow a building interacts with its environmentand how it behaves as a system.

In many schools, students and researchers alikelearn about energy efficiency and renewabletechnologies through partnerships—like theone with Oberlin—and programs like DOE’sEnergySmart Schools. NREL’s EnergySmartSchools Coordinator Patricia Plympton saysthat these programs are transitioning ourschools to new ways of using and teachingabout energy. “Sometimes students can teachus how to make classrooms more comfortableand productive using energy efficiency and re-newable technologies,” she says. “We’re alllearning from these living laboratories.”

Changing the Way We Live

In the desert community of Civano, outsideTucson, Arizona, all homes use 50% less energy

than a traditional home. The sun is used to heatwater for swimming pools and homes, and pho-tovoltaics help to offset electricity consumption.A network of bike and walking paths connectoffice buildings with homes to reduce the needfor driving. Native landscaping and efficientbuilding materials help the community livewithin the desert ecosystem, reducing waterconsumption and the need for air-conditioning.

Research on communities like Civano is help-ing scientists measure the effectiveness oftechnologies and improve designs. Energy per-formance is monitored and put into a comput-er system to model ways to make the homeseven more efficient. This huge network of liv-ing laboratories is a catalyst for change in thehome-building industry. Many large buildersare starting to see the benefits of producinghomes on a community scale that use 30% to50% less energy, reduceconstruction time andwaste by as muchas 50%, andprovide newproduct op-portunities tomanufacturers.

“We work with buildersand designers, who arechanging the way homes arebuilt,” said Paul Norton, NRELproject manager for DOE’sBuilding America program. “Our

research develops and refines technologies tomeet the builders’ specific needs, and also totest performance to find solutions when thingsdon’t work the way we thought they would.”

Getting to Zero—Buildings thatProduce Energy

Compared to the off-grid, energy self-sufficientEarthships of the 1970s, the Solar Patriot houseoutside of Washington, D.C., is a space station.Many people have built homes that are self-sus-taining, but the Solar Patriot house represents thefirst mass-market house that is connected to apower grid but not dependent on it. The houseuses a photovoltaic system to generate electrici-ty, aided by a solar hot-water system and passivesolar design, which has been so successful that ithas produced enough excess electricity to con-

sistently spin its electric meterbackward.

Tim Merrigan, NREL project manager for thenew DOE initiative for zero-energy homes, saysthat the Solar Patriot house is just one of themany zero-energy homes that will be tested dur-ing the next few years. NREL has awarded con-tracts to four teams of builders this past year todevelop new kinds of designs for homes.

“Most people can’t buy a zero-energy home to-day, but what does exist is a vast amount ofknowledge that will make zero-energy homesavailable to everyone in the future—buildingtechnology research as well as long-term fieldtesting of solar hot-water systems and photo-voltaic systems,” Merrigan said. “All that re-search exists and this program brings thatresearch together. The Zero Energy Buildingsprogram has very lofty goals, and we’re on thebrink of meeting those goals.”

What if your house were a mini-power plant,your roof shingles were photovoltaic panels, andheat collecting walls heated your home? Thesetechnologies already exist today, and are alreadybeing used in living laboratories across the nationto hone them for efficient, large-scale use in themarketplace. It may sound futuristic, but build-ings technologies like these are not far away.

Installation of PV-integrated standing-seam metal roof panels.

25

For eight days in 2002, 14 studentteams will participate in a compe-tition that will be a living laborato-ry for future designers, engineers,researchers, and communicators.The student teams will compete tocapture, convert, store, and useenough solar energy to power a“home” they will build themselves

on the Washington, DC, mall.Solar Decathletes will be requiredto provide all the energy for anentire household, including ahome-based business and thetransportation needs of the house-hold and business. During theevent, only the solar energy avail-able within the perimeter of eachhouse may be used to generate thepower needed to compete in theten Solar Decathlon contests. TheSolar Decathlon, sponsored byDOE and administered by NREL,will educate consumers about so-lar energy and energy-efficientproducts and also guide the nextgeneration of researchers, ar-chitects, engineers, andbuilders as they prepare tobegin their careers.

Competing for the Future

In a serene neighborhood just out-side Washington, D.C., the SolarPatriot house is quietly heralding thenext step in the transition to build-ings of the future. The house is soefficient that its 6-kW photovoltaicsystem produced more electricitythan the family used during 2-1/2months in early fall 2001. Also dur-ing that time, the house remainedfully powered, while the rest of theneighborhood went dark duringeight power outages. In addition, thefive-bedroom house is not only af-fordable for its rapidly growing areaof the country, but its exterior needs

no more maintenance than a con-ventional home. The standing-seammetal roof has a life expectancy of40-50 years. Maintenance on the so-lar systems is minimal.

A Future of Zero Energy

The “Solar Patriot,” in Virginia has a 6-kW PVsystem, solar water heater, geothermal heatpump, compact fluorescent lighting, high-efficiency appliances,and low-e windows.

With rotor diameters longer than football fields,wind turbines of the future will stand on towers400 feet high, operate even in low-wind areas, andhave adapting blades that change shape accordingto wind speed and direction. As researchers devel-

op the technology to grow turbines to gar-gantuan size, they also are working toshrink efficient designs—small turbines ef-fective for homes or small businesses.

Already, wind power has made great leapsin technology and price competitiveness during thepast two decades. Since the early 1980s, the cost ofwind power has decreased from 80¢/kWh (in 2002dollars) to about 4¢/kWh in high-wind-speed areas.And market use of wind power is growing at recordspeed—in the past two years alone, the amount ofelectric capacity produced by wind energy in theUnited States has almost doubled to 4,500 MW.

The challenge for wind power as we make thetransition to our energy future is to hone the tech-nology to be even more cost competitive and tooperate under even lower wind speeds. By operat-ing efficient turbines at low wind speeds—an aver-age of 13.5 miles per hour annually versus the 15miles per hour necessary now—20 times moreland in the nation will be able to cost effectivelyaccess wind power.

With this goal in mind, the U.S.Department of Energy, NREL, andother wind research organizations

are focusing on developing, testing,and lowering the costs of turbine com-

ponents that operate in lower speeds.“We’re putting our whole research program

behind this—aerodynamics, understanding tur-bulence, advanced controls, advanced materi-als, power electronics,” says NREL’s Sue Hock,wind energy technology manager. According toHock, only with continued low-wind researchwill wind power reach its goal of being costcompetitive at low wind speeds with fuels by2010—by bringing low-wind costs down from6¢/kWh to 3¢/kWh, and even to below 2¢/kWhby 2020.

The Components of Wind Turbines

A wind turbine is composed of blades turning arotor that is situated on top of a tower. Drivetraincomponents (which can include generators, gear-boxes, shafts, and bearings) transfer the slow-ro-tating mechanical energy from the rotor andconvert it to electrical energy. Researchers arestudying all of these components to make themmore effective and less expensive to manufactureand operate.

One NREL program called WindPACT (WindPartnerships for Advanced ComponentTechnologies) combines laboratory researchwith applied, industry research to improve low-wind components. Promising research ideas andconcepts generated in the laboratory are furtherdeveloped and tested by a joint team of industryand laboratory researchers through WindPACT.Partnerships between new industry membersand existing wind compa-nies are encouraged, sothe program attracts neworganizations and ideasinto the arena.

MakingTowers Taller

One WindPACT studylooks at how towers canbe improved. Becausewind speed increases withheight above the ground,taller towers can findhigher wind speeds evenin lower-wind areas. Buttaller tower designs beingtested now, between 200and 300 feet, are still

causing serious logistics problems during installa-tion. The study found several alternative methodsof constructing very tall towers, ranging from self-erecting concrete towers to telescoping tubes orjack-up devices. This work will form the founda-tion for further study by designers of low-windtechnologies in the years ahead.

Sharpening Blades

Blade designs and manufacturing processes are al-so being honed for low-wind speeds. Transporting300-foot blades across the country can be ex-pensive and complicated—so researchers arelooking at ways to set up mobile manufactur-ing “factories” at the site where the blades willbe installed. WindPACT also found that newand lighter-weight materials will be necessaryto grow blades to the larger sizes necessary. Inaddition to fiberglass (the material currentlyused) researchers are looking at carbon, whichis stronger and lighter weight than fiberglass, orglass-carbon hybrids.

26 27

Modern wind turbines, such as these in Northern Colorado,generate competitive electricity in high-wind-speed areas.NREL’s research is aimed at developing wind turbines thatgenerate inexpensive electricity in low-wind-speed areas,opening up a vast wind resource for the nation.

To develop wind turbines thatproduce inexpensive electricity(3¢/kWh or less) in low-wind-

speed areas, researchers arestudying all the components ofa wind turbine—rotors (whichinclude blades and hub), tow-

ers, gearboxes, generators,shafts, and controllers—to

make them more effective andless expensive.

A blade for a 750-kWwind turbine is beingfatigue tested at NREL’sIndustrial User Facility.

NREL’s National Wind Technology Center(NWTC) south of Boulder, Colorado, houses thenation’s most advanced, state-of-the-art facilitiesfor testing wind energy systems. Eleven tur-bines—up to 600-kW capacity—tower over theplains, silhouetted by the foothills of the RockyMountains. Some of the wind turbines are pro-totypes of new designs, and others are baselinemachines used for testing innovative compo-nents and control strategies.

Walt Musial, NREL’s development testing teamleader, says the wind site provides services to in-dustry that they usually don’t have access to:“This kind of testing and these kinds of facilitiescan be too expensive and too difficult to set upfor one manufacturer.” And, he says, the

National Wind Technology Center’s facil-ities are unique—the only blade-testinglaboratory in North America that can testmegawatt-scale blades and the only dy-namometer facility that can do full-sys-tem wind turbine testing.

Through the installation and testing ofthese diverse kinds of turbines, re-searchers are learning how they operateand perform and how to enhance com-puter-aided analysis and design. Duringthe next several years, NREL plans to in-stall as many as 16 more experimentalturbines at the center.

The site also hosts three specialized test facili-ties: The 10,000-square-foot Industrial UserFacility tests the performance and structural reli-ability of individual wind turbine blades up to85 feet long. This facility is the center for collab-orative activities with the wind industry, and itsunique building design enables several wind en-ergy companies to simultaneously disassembleturbines, analyze the individual components,and modify the components while protectingproprietary information.

The Dynamometer Test Facility was constructedin response to industry requests. The facilitygives engineers the ability to conduct lifetimeendurance tests on a wide range of wind turbinedrivetrains, gearboxes, brakes, control systems,and generators at various speeds, using low orhigh torque. A few months of testing on the dy-namometer can simulate the equivalent of 30years of use and a lifetime of braking cycles.Thus, engineers can determine which compo-nents are susceptible to wear and need re-designing to improve reliability and enduranceof the components.

At the Hybrid Power Test Facility, researcherstest existing systems and develop advanced con-trols for systems that use a variety of renewableand nonrenewable sources. The facility providesboth real and simulated wind and photovoltaicenergy sources, battery banks, and diesel gener-ators, and allows testing under controlled com-binations of solar and wind resources.

Testing the Wind

At NREL’s Dynamometer Test Facility, adrivetrain for a 750-kW wind turbine un-dergoes tests to measure loading under re-alistic conditions and endurance tests toverify design life.

Rotor

Shafts

Controller

Gear Box

Break

Tower

Generator

With rotor diameters longer than football fields,wind turbines of the future will stand on towers400 feet high, operate even in low-wind areas, andhave adapting blades that change shape accordingto wind speed and direction. As researchers devel-

op the technology to grow turbines to gar-gantuan size, they also are working toshrink efficient designs—small turbines ef-fective for homes or small businesses.

Already, wind power has made great leapsin technology and price competitiveness during thepast two decades. Since the early 1980s, the cost ofwind power has decreased from 80¢/kWh (in 2002dollars) to about 4¢/kWh in high-wind-speed areas.And market use of wind power is growing at recordspeed—in the past two years alone, the amount ofelectric capacity produced by wind energy in theUnited States has almost doubled to 4,500 MW.

The challenge for wind power as we make thetransition to our energy future is to hone the tech-nology to be even more cost competitive and tooperate under even lower wind speeds. By operat-ing efficient turbines at low wind speeds—an aver-age of 13.5 miles per hour annually versus the 15miles per hour necessary now—20 times moreland in the nation will be able to cost effectivelyaccess wind power.

With this goal in mind, the U.S.Department of Energy, NREL, andother wind research organizations

are focusing on developing, testing,and lowering the costs of turbine com-

ponents that operate in lower speeds.“We’re putting our whole research program

behind this—aerodynamics, understanding tur-bulence, advanced controls, advanced materi-als, power electronics,” says NREL’s Sue Hock,wind energy technology manager. According toHock, only with continued low-wind researchwill wind power reach its goal of being costcompetitive at low wind speeds with fuels by2010—by bringing low-wind costs down from6¢/kWh to 3¢/kWh, and even to below 2¢/kWhby 2020.

The Components of Wind Turbines

A wind turbine is composed of blades turning arotor that is situated on top of a tower. Drivetraincomponents (which can include generators, gear-boxes, shafts, and bearings) transfer the slow-ro-tating mechanical energy from the rotor andconvert it to electrical energy. Researchers arestudying all of these components to make themmore effective and less expensive to manufactureand operate.

One NREL program called WindPACT (WindPartnerships for Advanced ComponentTechnologies) combines laboratory researchwith applied, industry research to improve low-wind components. Promising research ideas andconcepts generated in the laboratory are furtherdeveloped and tested by a joint team of industryand laboratory researchers through WindPACT.Partnerships between new industry membersand existing wind compa-nies are encouraged, sothe program attracts neworganizations and ideasinto the arena.

MakingTowers Taller

One WindPACT studylooks at how towers canbe improved. Becausewind speed increases withheight above the ground,taller towers can findhigher wind speeds evenin lower-wind areas. Buttaller tower designs beingtested now, between 200and 300 feet, are still

causing serious logistics problems during installa-tion. The study found several alternative methodsof constructing very tall towers, ranging from self-erecting concrete towers to telescoping tubes orjack-up devices. This work will form the founda-tion for further study by designers of low-windtechnologies in the years ahead.

Sharpening Blades

Blade designs and manufacturing processes are al-so being honed for low-wind speeds. Transporting300-foot blades across the country can be ex-pensive and complicated—so researchers arelooking at ways to set up mobile manufactur-ing “factories” at the site where the blades willbe installed. WindPACT also found that newand lighter-weight materials will be necessaryto grow blades to the larger sizes necessary. Inaddition to fiberglass (the material currentlyused) researchers are looking at carbon, whichis stronger and lighter weight than fiberglass, orglass-carbon hybrids.

27

Modern wind turbines, such as these in Northern Colorado,generate competitive electricity in high-wind-speed areas.NREL’s research is aimed at developing wind turbines thatgenerate inexpensive electricity in low-wind-speed areas,opening up a vast wind resource for the nation.

To develop wind turbines thatproduce inexpensive electricity(3¢/kWh or less) in low-wind-

speed areas, researchers arestudying all the components ofa wind turbine—rotors (whichinclude blades and hub), tow-

ers, gearboxes, generators,shafts, and controllers—to

make them more effective andless expensive.

A blade for a 750-kWwind turbine is beingfatigue tested at NREL’sIndustrial User Facility.

NREL’s National Wind Technology Center(NWTC) south of Boulder, Colorado, houses thenation’s most advanced, state-of-the-art facilitiesfor testing wind energy systems. Eleven tur-bines—up to 600-kW capacity—tower over theplains, silhouetted by the foothills of the RockyMountains. Some of the wind turbines are pro-totypes of new designs, and others are baselinemachines used for testing innovative compo-nents and control strategies.

Walt Musial, NREL’s development testing teamleader, says the wind site provides services to in-dustry that they usually don’t have access to:“This kind of testing and these kinds of facilitiescan be too expensive and too difficult to set upfor one manufacturer.” And, he says, the

National Wind Technology Center’s facil-ities are unique—the only blade-testinglaboratory in North America that can testmegawatt-scale blades and the only dy-namometer facility that can do full-sys-tem wind turbine testing.

Through the installation and testing ofthese diverse kinds of turbines, re-searchers are learning how they operateand perform and how to enhance com-puter-aided analysis and design. Duringthe next several years, NREL plans to in-stall as many as 16 more experimentalturbines at the center.

The site also hosts three specialized test facili-ties: The 10,000-square-foot Industrial UserFacility tests the performance and structural reli-ability of individual wind turbine blades up to85 feet long. This facility is the center for collab-orative activities with the wind industry, and itsunique building design enables several wind en-ergy companies to simultaneously disassembleturbines, analyze the individual components,and modify the components while protectingproprietary information.

The Dynamometer Test Facility was constructedin response to industry requests. The facilitygives engineers the ability to conduct lifetimeendurance tests on a wide range of wind turbinedrivetrains, gearboxes, brakes, control systems,and generators at various speeds, using low orhigh torque. A few months of testing on the dy-namometer can simulate the equivalent of 30years of use and a lifetime of braking cycles.Thus, engineers can determine which compo-nents are susceptible to wear and need re-designing to improve reliability and enduranceof the components.

At the Hybrid Power Test Facility, researcherstest existing systems and develop advanced con-trols for systems that use a variety of renewableand nonrenewable sources. The facility providesboth real and simulated wind and photovoltaicenergy sources, battery banks, and diesel gener-ators, and allows testing under controlled com-binations of solar and wind resources.

Testing the Wind

At NREL’s Dynamometer Test Facility, adrivetrain for a 750-kW wind turbine un-dergoes tests to measure loading under re-alistic conditions and endurance tests toverify design life.

September 11 changed America. It changed ourbelief that our shores were immune to attack. Itchanged the way in which many of us do busi-ness. It changed our idea of how our freedomsand our security are intertwined.

And it changed our concept of how impor-tant energy security—especially in the formof homegrown and diverse energy sup-plies—is to national security.

President Bush has stated that “one of the keys toenergy security in America, and national security,is to have a diversified energy base,” and that“Over-dependence on any one source of energy,

especially a foreign source, leaves usvulnerable to price shocks, supply in-terruptions, and…blackmail.”

Blackmail, indeed, and worse—sabo-tage of energy supplies in an effort tochoke the vitality of our economy,eviscerate the vigor of our way of life,and curb our hard-won freedoms.

It is no wonder, then, thatSecretary of Energy SpencerAbraham has stated that “. . . en-ergy and science programs shouldbe judged by whether they ad-vance this nation’s energy—andhence, national—security.”

The R&D that NREL performsfor the Department of Energy

on renewable energy and energy efficiency is wellplaced in this regard.

When NREL began its mission 25 years ago, the popularrefrain was, “No one can embargo the sun.” Well, no onecan embargo or disrupt energy that isn’t spent, either—such as the energy saved through energy-efficient tech-nologies. We can incorporate energy efficiency into everyhome, building, business, industry, and vehicle. And thesimple fact is, the more efficient you become, the lessvulnerable you are to disruptions of energy supply.

And renewable energy? The technologies and the ener-gy resources for renewable energy are homegrown. Weunravel the science, develop the technologies, andmanufacture the systems here, in America. And the re-sources themselves—sunshine, wind, water, biomass,and the heat of the Earth—are vast, ubiquitous, safe,and uninterruptible here, in America.

And it is in America that we can use these resourcesand technologies to enhance national security. We canenhance it directly through our national defense by us-ing energy efficiency technologies to improve fuel effi-ciencies for a wide range of weapons platforms and to

make supply lines less vulnerable. We can em-ploy biomass-derived fuels to supplement otherfuels for strategic military purposes. And wecan deploy photovoltaic systems for remote ormobile field service.

Photovoltaic systems, in fact, have longplayed an important military and strategicrole. They are the preferred power supply forthe Earth-orbiting satellites that the U.S. mili-tary and intelligence agencies rely on for gath-ering and communicating information fromaround the world.

But renewable energy and energy efficiencytechnologies are equally important for other as-pects of our national security. For example,certain liquid desiccants—often used for build-ing dehumidification and cooling—are wellknown for their ability to absorb water. Butthey also can absorb a wide variety of sus-pended particles from the air, including poten-tially pathogenic bacterial and fungal spores.As a consequence, air-conditioning equipmentbased on liquid desiccants may prove to be avaluable technology for removing and destroy-ing potential airborne pathogens—dependingon how well the liquid desiccant-based airconditioner can remove these particles fromthe air and how effective the liquid-desiccantmaterial is in deactivating the absorbedpathogens. Currently, researchers are investi-gating both of these issues.

Bacteria and viruses can also be easily filteredout of our water supply with an R&D 100Award-winning technology developed byNREL and its partners. This technology is basedon nanoscale ceramic fibers that have an ex-tremely high surface area and a chemical affin-ity that makes them particularly adept forfiltration of microbial pathogens and viruseswhose sizes range from a few nanometers to afew micrometers. This material is also ideal forpurifying blood plasma, sampling and detect-ing pathogens in lakes and streams, and re-moving heavy metals from water.

And consider again those PV-powered, Earth-orbiting satellites. They are at the heart oftelecommunications, which has become funda-mental to the way the nation communicatesand does business. Telecommunications alsohas become extremely valuable in times of dis-aster—natural or man-induced—for keepingcommunications open and for locating peopleand areas of concern. And because photo-voltaics and other renewable energy systems

are portable and can be employed stand-alone,in times of disaster they can be used to refriger-ate vital medical supplies and to provide powerfor critical services.

Renewable energy and energy efficiency tech-nologies represent the ultimate distributed re-source. For example, renewable electrictechnologies—photovoltaics, wind energy, con-centrated solar power, bioelectric units—addredundancy, security, and reliability to any sys-tem, whether for a single home, a business, arepeater station, a community, or for an entiregrid network. With renewable electric systemsinterconnected with other resources and tech-nologies in a “smart” grid network, electricitycan be rerouted around any damaged portionof the network to keep vital energy flowing.

These are just a few ways in which re-newable energy and energy effi-ciency technologies are beingused today. But their po-tential for energy andnational securi-ty is enor-mous.

Bioenergytechnolo-gies, for exam-ple, carry a greatprospect for sup-plementing and dis-placing imported fossil fuels and for supplyingfeedstock for chemicals, fibers, and other mate-rials. And one day we will be able to use re-newable energy to generate hydrogen inalmost any locality of the nation, and then touse that hydrogen to fuel our aircraft, heat ourhomes and offices, power our cars, and pro-vide us with electricity.

In these and many otherways, renewable energyand energy efficiency tech-nologies will help reshapeAmerica’s energy infra-structure from one that re-lies heavily on foreignsupplies and centrally de-livered power to one thatis decentralized and moredependent on domesticand local resources. Andthey will help moveAmerica toward a moresecure energy future.

PV-powered Earth-orbitingsatellites have become es-sential to America’s well be-ing. They are at the heart ofan expanding telecommuni-cations network that gath-ers, deciphers, and transmitsinformation on weather, cli-mate, aerosols, communica-tions, oceans, volcanoes,trace gases, storms, disas-ters, troop movements, andmuch more.

(Top) Wind turbines generateelectricity for a U.S. Naval base

on San Clemente Island.(Center) Solar wall pro-vides heat and ventila-

tion for ahelicopter main-tenance hangar

at Fort Carsonin Colorado

Springs.(Bottom) A solar electric panelsupplies power for refrigerating

vaccines at a remote healthcenter. (Background) Biomass-derived fuel supplements fossil

fuel used in a U.S. Army vehicle.Solar arrays provide 15 kW of

supplemental powerfor the Pentagon.

28

September 11 changed America. It changed ourbelief that our shores were immune to attack. Itchanged the way in which many of us do busi-ness. It changed our idea of how our freedomsand our security are intertwined.

And it changed our concept of how impor-tant energy security—especially in the formof homegrown and diverse energy sup-plies—is to national security.

President Bush has stated that “one of the keys toenergy security in America, and national security,is to have a diversified energy base,” and that“Over-dependence on any one source of energy,

especially a foreign source, leaves usvulnerable to price shocks, supply in-terruptions, and…blackmail.”

Blackmail, indeed, and worse—sabo-tage of energy supplies in an effort tochoke the vitality of our economy,eviscerate the vigor of our way of life,and curb our hard-won freedoms.

It is no wonder, then, thatSecretary of Energy SpencerAbraham has stated that “. . . en-ergy and science programs shouldbe judged by whether they ad-vance this nation’s energy—andhence, national—security.”

The R&D that NREL performsfor the Department of Energy

on renewable energy and energy efficiency is wellplaced in this regard.

When NREL began its mission 25 years ago, the popularrefrain was, “No one can embargo the sun.” Well, no onecan embargo or disrupt energy that isn’t spent, either—such as the energy saved through energy-efficient tech-nologies. We can incorporate energy efficiency into everyhome, building, business, industry, and vehicle. And thesimple fact is, the more efficient you become, the lessvulnerable you are to disruptions of energy supply.

And renewable energy? The technologies and the ener-gy resources for renewable energy are homegrown. Weunravel the science, develop the technologies, andmanufacture the systems here, in America. And the re-sources themselves—sunshine, wind, water, biomass,and the heat of the Earth—are vast, ubiquitous, safe,and uninterruptible here, in America.

And it is in America that we can use these resourcesand technologies to enhance national security. We canenhance it directly through our national defense by us-ing energy efficiency technologies to improve fuel effi-ciencies for a wide range of weapons platforms and to

make supply lines less vulnerable. We can em-ploy biomass-derived fuels to supplement otherfuels for strategic military purposes. And wecan deploy photovoltaic systems for remote ormobile field service.

Photovoltaic systems, in fact, have longplayed an important military and strategicrole. They are the preferred power supply forthe Earth-orbiting satellites that the U.S. mili-tary and intelligence agencies rely on for gath-ering and communicating information fromaround the world.

But renewable energy and energy efficiencytechnologies are equally important for other as-pects of our national security. For example,certain liquid desiccants—often used for build-ing dehumidification and cooling—are wellknown for their ability to absorb water. Butthey also can absorb a wide variety of sus-pended particles from the air, including poten-tially pathogenic bacterial and fungal spores.As a consequence, air-conditioning equipmentbased on liquid desiccants may prove to be avaluable technology for removing and destroy-ing potential airborne pathogens—dependingon how well the liquid desiccant-based airconditioner can remove these particles fromthe air and how effective the liquid-desiccantmaterial is in deactivating the absorbedpathogens. Currently, researchers are investi-gating both of these issues.

Bacteria and viruses can also be easily filteredout of our water supply with an R&D 100Award-winning technology developed byNREL and its partners. This technology is basedon nanoscale ceramic fibers that have an ex-tremely high surface area and a chemical affin-ity that makes them particularly adept forfiltration of microbial pathogens and viruseswhose sizes range from a few nanometers to afew micrometers. This material is also ideal forpurifying blood plasma, sampling and detect-ing pathogens in lakes and streams, and re-moving heavy metals from water.

And consider again those PV-powered, Earth-orbiting satellites. They are at the heart oftelecommunications, which has become funda-mental to the way the nation communicatesand does business. Telecommunications alsohas become extremely valuable in times of dis-aster—natural or man-induced—for keepingcommunications open and for locating peopleand areas of concern. And because photo-voltaics and other renewable energy systems

are portable and can be employed stand-alone,in times of disaster they can be used to refriger-ate vital medical supplies and to provide powerfor critical services.

Renewable energy and energy efficiency tech-nologies represent the ultimate distributed re-source. For example, renewable electrictechnologies—photovoltaics, wind energy, con-centrated solar power, bioelectric units—addredundancy, security, and reliability to any sys-tem, whether for a single home, a business, arepeater station, a community, or for an entiregrid network. With renewable electric systemsinterconnected with other resources and tech-nologies in a “smart” grid network, electricitycan be rerouted around any damaged portionof the network to keep vital energy flowing.

These are just a few ways in which re-newable energy and energy effi-ciency technologies are beingused today. But their po-tential for energy andnational securi-ty is enor-mous.

Bioenergytechnolo-gies, for exam-ple, carry a greatprospect for sup-plementing and dis-placing imported fossil fuels and for supplyingfeedstock for chemicals, fibers, and other mate-rials. And one day we will be able to use re-newable energy to generate hydrogen inalmost any locality of the nation, and then touse that hydrogen to fuel our aircraft, heat ourhomes and offices, power our cars, and pro-vide us with electricity.

In these and many otherways, renewable energyand energy efficiency tech-nologies will help reshapeAmerica’s energy infra-structure from one that re-lies heavily on foreignsupplies and centrally de-livered power to one thatis decentralized and moredependent on domesticand local resources. Andthey will help moveAmerica toward a moresecure energy future.

PV-powered Earth-orbitingsatellites have become es-sential to America’s well be-ing. They are at the heart ofan expanding telecommuni-cations network that gath-ers, deciphers, and transmitsinformation on weather, cli-mate, aerosols, communica-tions, oceans, volcanoes,trace gases, storms, disas-ters, troop movements, andmuch more.

(Top) Wind turbines generateelectricity for a U.S. Naval base

on San Clemente Island.(Center) Solar wall pro-vides heat and ventila-

tion for ahelicopter main-tenance hangar

at Fort Carsonin Colorado

Springs.(Bottom) A solar electric panelsupplies power for refrigerating

vaccines at a remote healthcenter. (Background) Biomass-derived fuel supplements fossil

fuel used in a U.S. Army vehicle.Solar arrays provide 15 kW of

supplemental powerfor the Pentagon.

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Executive Editor: Gary Cook, NREL

Writers: Kyra Epstein, Howard Brown, and Gary Cook, NREL

Design/Layout: Al Hicks, NREL

Cover Design: Ray David, NREL

Photography: Jim Yost, Jim Yost Photography;Warren Gretz, NREL

Editor: Michelle Kubik, NREL

Contributors/Reviewers: Many at NREL

NREL 2002 Research Review Staff