environmental science 13e chapter 13: energy. core case study: amory lovins and the rocky mountain...
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ENVIRONMENTAL SCIENCE 13e
CHAPTER 13:Energy
Core Case Study: Amory Lovins and the Rocky Mountain Institute (1)
• 1984: home and office building in Snowmass, CO
• Heat:– Sun
– Heavy roof insulation
– Thick stone walls
– Energy-efficient windows
– Waste-heat recovery
Core Case Study: Amory Lovins and the Rocky Mountain Institute (2)
• Sun– 99% of heat and hot water– 95% of daytime lighting– 90% of household electricity
• Energy-efficient electrical appliances and computers
• Rocky Mountain Institute– Promotes energy-efficient buildings and
transportation
Fig. 13-1, p. 296
13-1 What Major Sources of Energy Do We Use?
• Concept 13-1A About three-quarters of the world’s commercial energy comes from nonrenewable fossil fuels, and the rest comes from nonrenewable nuclear fuel and renewable sources.
• Concept 13-1B Net energy is the amount of high-quality energy available from a resource minus the amount of energy needed to make it available.
• What do we need to consider when evaluating energy resources?
Evaluating Energy Resources
• The supply
• The environmental impact
• How much net useful energy they provide
Fig. 13-2, p. 298
Commercial energy use by source
What can be said about renewable vs non-renewable?
Science Focus: Net Energy
• It takes energy get energy. • What steps are involved in the oil industry that require
energy? • Second law of thermodynamics (what happens to the
energy at each step?)
• Net energy: The usable amount of high quality energy available from a given quantity of an energy resource minus the energy needed to find, extract, process, and get that energy to consumers
• Net energy ratio• Ex. Nuclear fuel cycle, how much energy we get out vs
how much energy we put in
13-2 What Are the Advantages and Disadvantages of Fossil Fuels?
• Concept 13-2 Oil, natural gas, and coal are currently abundant and relatively inexpensive, but using them causes air and water pollution, degrades large areas of land, and releases greenhouse gases to the atmosphere.
Dependence on Oil (1)
• Petroleum (crude oil)– Also called light oil– Trapped underground or under ocean with
natural gas– Fossil fuels
• Extraction– U.S. peak production– Global peak production: the point in time when we reach the
maximum overall rate of crude oil production for the whole world. Once we pass this point, what will happen to global oil production?
Dependence on Oil (2)
• Transportation
• Refining
• Petrochemicals
Asphalt
GasesLowest Boiling Point
Highest Boiling Point
Gasoline
Aviation fuel
Heating oil
Dieseloil
Heatedcrude oil
Furnace
Naphtha
Greaseand wax
Fig. 13-3, p. 300
Fig. 13-3, p. 300
Supplement 9, Fig. 3, p. S40
How Long Will Crude Oil Supplies Last?
• Crude oil is the single largest source of commercial energy in world and U.S.
How Long Will Crude Oil Supplies Last?
• Crude oil is the single largest source of commercial energy in world and U.S.
• Proven oil reserves– Identified deposits that can be extracted
profitably at today’s prices with today’s technology
How Long Will Crude Oil Supplies Last?
• Crude oil is the single largest source of commercial energy in world and U.S.
• Proven oil reserves– Identified deposits that can be extracted
profitably at today’s prices with today’s technology
– Geologists predict known and projected global reserves of crude oil will be 80% depleted between 2050 and 2100 depending on consumption rates
What are our options?
What are our options?
• Look for more oil
• Use and waste less oil
• Use other energy options
• Yes, yes, and yes!
Fig. 13-4, p. 301
2050
Year
Bar
rels
of
oil
per
yea
r (b
illi
on
s)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Projected U.S.oil consumption
Arctic refuge oiloutput over 50 years
2000 2010 2020 2030 2040
*United States Oil Production and Use (1)
• U.S.– 93% of energy from fossil fuels
– 39% from crude oil
– Produces 9% of world’s crude oil
– Uses 25% of world production
– Has 2% of proven crude oil reserves
United States Oil Production and Use (2)
• Domestic oil production– Off-shore drilling
– Alaska
• Future U.S. production
• Consumption versus production
• Oil imports– 2008: imported 58% of crude oil
Fig. 13-5, p. 301
DisadvantagesNeed to findsubstitutes within 50years
Large governmentsubsidies
Environmental costsnot included inmarket price
Artificially low priceencourages wasteand discouragessearch for alternatives
Pollutes air whenproduced and burned
Releases CO2 whenburned
Can cause waterpollution
Ample supply for42–93 years
Low cost
High net energyyield
Easily transportedwithin andbetween countries
Low land use
Technology is welldeveloped
Efficientdistribution system
Trade-Offs
Conventional OilAdvantages
Oil Sand
• Oil sand (tar sand): mixture of clay, water and bitumen
• Bitumen: thick, sticky, tar like heavy oil with high sulfur content
• Northeastern Alberta in Canada has ¾ world’s tar sands resources
• Under boreal forest• Huge environmental cost
Tar sands
• http://www.good.is/post/think-nuclear-or-coal-is-bad-tar-sands-mining-is-coming-to-utah/
• http://www.youtube.com/watch?v=YkwoRivP17A&feature=related
Oil shale
• Contain kerogen• Shale Oil• About 72% of world’s estimated oil shale
reserves buries in government owed land in US states of Colorado, Wyoming, and Utah in Green River formation
• What are the problems? Low net energy, requires huge amount of water to produce (Colorado River System), severe water pollution, air pollution, CO2 emission …
Fig. 13-6, p. 303
Fig. 13-7, p. 303
Heavy Oils from OilShale and Tar Sand
High cost (oil shale)
Low net energy yield
Environmental costsnot included inmarket price
Large amounts ofwater needed forprocessing
Severe land disruption
Severe waterpollution
Air pollution and CO2 emissions when produced and burned
Technologywell-developed(tar sand)
Efficientdistribution system in place
Easily transportedwithin andbetween countries
Large potentialsupplies, especiallytar sands inCanada
Moderate cost(tar sand)
Trade-Offs
Advantages Disadvantages
Natural Gas Is a Useful and Clean-burning Fossil Fuel (1)
• Natural gas
• Conventional natural gas
• Unconventional natural gas
• Liquefied petroleum gas (LPG)
• Less carbon dioxide emitted per unit of energy than with crude oil, tar sand, shale oil
Natural Gas Is a Useful and Clean-burning Fossil Fuel (2)
• Liquefied natural gas (LNG)• World supply of conventional natural
gas – 62-125 years
• Unconventional natural gas– Coal-bed methane gas– Methane hydrate
Fig. 13-8, p. 304
Conventional Natural Gas
Nonrenewable resource
Releases CO2 when burned
Government subsidies
Environmental costs notincluded in market price
Methane(a greenhouse gas) canleak from pipelines
Difficult to transfer fromone country to another
Can be shipped acrossocean only as highlyexplosive LNG
Ample supplies
High net energy yield
Low cost
Less air pollution thanother fossil fuels
Lower CO2 emissions thanother fossil fuels
Easily transported bypipeline
Low land use
Good fuel for fuel cells,gas turbines, and motorvehicles
Trade-Offs
Advantages Disadvantages
Coal Is a Plentiful But Dirty Fuel (1)
• Used in electricity production
• World’s most abundant fossil fuel
• U.S. reserves should last about 250 years
• Sulfur and particulate pollutants
• Mercury and radioactive pollutants
Coal Is a Plentiful But Dirty Fuel (2)
• Heavy carbon dioxide emissions
• Pollution control and environmental costs
• China major builder of coal plants
Highly desirable fuel because of its high heat content andlow sulfur content; supplies are limited in most areas
Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content
Low heat content; lowsulfur content; limitedsupplies in most areas
Partially decayed plantmatter in swamps andbogs; low heat content
Peat(not a coal)
Lignite(brown coal)
Bituminous(soft coal)
Increasing heat and carbon content Increasing moisture content
Heat Heat Heat
Pressure Pressure Pressure
Anthracite(hard coal)
Fig. 13-9, p. 305
Stack
Waste heat
Cooling towertransfers wasteheat to atmosphere
Pulverizing mill
TurbineCoal bunker
GeneratorCooling loop
Condenser
Boiler
Filter
Toxic ash disposal
Fig. 13-10, p. 306
Coal burning power plant
TVA Coal fired power plant
• http://www.tva.com/power/coalart.htm
• http://www.newsweek.com/photo/2009/07/21/photos--the-worst-man-made-environmental-disasters.html
Fig. 13-10, p. 306
Coal-fired electricity
286%
Synthetic oil and gas produced
from coal
150%
Coal 100%
Tar sand 92%
Oil 86%
Natural gas 58%
Nuclear power fuel cycle 17%
Geothermal 10%Stepped Art
Fig. 13-11, p. 306
CO2 Emissions per unit of electrical energy
Fig. 13-12, p. 307
DisadvantagesSevere land disturbance,air pollution, and waterpollution
Severe threat to humanhealth when burned
Environmental costs notincluded in market price
Large governmentsubsidies
High CO2 emissionswhen produced andburned
Radioactive particle andtoxic mercury emissions
Air pollution can be reduced withimproved technology
Well-developed technology
Low cost
High net energy yield
Ample supplies (225–900 years)
Trade-Offs
Coal
Advantages
Case Study: The Growing Problem of Coal Ash
• Highly toxic
• Often stored in ponds– Ponds can rupture
• Groundwater contamination
• EPA: in 2009 called for classifying coal ash as hazardous waste– Opposed by coal companies
TVA coal ash spill
• http://earthfirst.com/americas-top-10-worst-man-made-environmental-disasters/
Clean Coal Campaign
• Coal industry– Rich and powerful– Fought against labeling carbon dioxide a
greenhouse gas
• “Clean coal” touted by coal industry– Mining harms the environment– Burning creates carbon dioxide and toxic
chemicals
• Plan to capture and store carbon dioxide
Converting Coal into Gaseous and Liquid Fuels
• Synfuels
• Coal gasification– Synthetic natural gas (SNG)
• Coal liquefaction– Methanol or synthetic gasoline
• Extracting and burning coal more cleanly
Fig. 13-13, p. 309
DisadvantagesLow to moderate net energy yield
Higher cost than coal
Requires mining 50% more coal
Environmental costs not includedin market price
High environmental impact
Large government subsidies
High water use
Higher CO2 emissions than coal
Large potential supply
Vehicle fuel
Moderate cost
Lower air pollutionthan coal whenburned
Trade-Offs
Synthetic Fuels
Advantages
13-3 What Are the Advantages and Disadvantages of Nuclear Energy?• Concept 13-3 The nuclear power fuel
cycle has a low environmental impact and a very low accident risk, but its use has been limited because of high costs, a low net energy yield, long-lived radioactive wastes, vulnerability to sabotage, and the potential for spreading nuclear weapons technology.
How Does a Nuclear FissionReactor Work?
• Nuclear fission
• Light-water reactors
• Boil water to produce steam to turn turbines to generate electricity
• Radioactive uranium as fuel
• Control rods, coolant, and containment vessels
TVA
• http://www.tva.gov/power/nuclear/wattsbar_howworks.htm
• http://www.tvakids.com/videos/pressurized_water_animation.htm
Coolwaterinput
Small amounts ofradioactive gases
Periodic removal andstorage of radioactive
wastes and spentfuel assemblies
Periodic removaland storage of
radioactiveliquid wastes
Control rods
Heat exchanger
Containment shell
Steam
Water
Uraniumfuel input(reactor core)
Hotcoolant
Coolant
Moderator
Coolantpassage
Shielding
Waste heat
Water source(river, lake, ocean)
Useful electricalenergy
About 25%
GeneratorTurbine
Hotwateroutput
Condenser
Pressurevessel
Fig. 13-14, p. 310
Pump
Waste heatPump
Pump
Pump
Fig. 13-14, p. 310
Safety and Radioactive Wastes
• On-site storage of radioactive wastes
• Safety features of nuclear power plants
• Nuclear fuel cycle
• Reactor life cycle
• Large amounts of very radioactive wastes
Fig. 13-15, p. 311
Fig. 13-15, p. 311
Fuel assemblies
Fuel fabricationEnrichmentof UF6
Temporary storageof spent fuel assemblies
underwater or in dry casks
Low-level radiationwith long half-life
Geologic disposalof moderate and high-levelradioactive wastes
(conversion of enrichedUF6 to UO2 and fabricationof fuel assemblies)
Uranium-235 as UF6 Plutonium-239 as PuO2
Decommissioningof reactor
Reactor
Spent fuelreprocessing
Conversionof U3O8
to UF6
Fig. 13-16, p. 312
Open fuel cycle today
Recycling of nuclear fuel
Mining uranium ore (U3O8 )
Nuclear Fuel Cycle
What Happened to Nuclear Power?
• Optimism of 1950s is gone
• Comparatively expensive source of power
• No new plants in U.S. since 1978
• Disposing of nuclear waste is difficult
• Three Mile Island (1979)
Japan’s Nuclear Disaster
• http://www.guardian.co.uk/world/video/2011/mar/14/japan-tsunami-amateur-footage-video
Case Study: Chernobyl Disaster
• Ukraine (1986)
• Explosions and partial meltdown
• Huge radioactive release to atmosphere
• Estimated death toll: 9,000–212,000
• Radioactive fallout and long-term health effects
• Lesson – worldwide consequences
Fig. 13-17, p. 313
Conventional Nuclear Fuel Cycle
Cannot competeeconomically without hugegovernment subsidies
Low net energy yield
High environmental impact(with major accidents)
Environmental costs notincluded in market price
Risk of catastrophic accidents
No widely acceptable solutionfor long-term storage ofradioactive wastes
Subject to terrorist attacks
Spreads knowledge andtechnology for buildingnuclear weapons
Large fuel supply
Low environmentalimpact (withoutaccidents)
Emits 1/6 as much CO2
as coal
Moderate land disruptionand water pollution(without accidents)
Moderate land use
Low risk of accidentsbecause of multiplesafety systems (except forChernobyl-type reactors)
Trade-Offs
DisadvantagesAdvantages
Fig. 13-18, p. 314
Coal vs. Nuclear
Ample supply ofuranium
Low net energy yield
Low air pollution
Lower CO2 emissions
Much lower landdisruption fromsurface mining
Moderate land use
High cost (even withhuge subsidies)
Ample supply
High net energyyield
Very high airpollution
High CO2
emissions
High landdisruption fromsurface mining
High land use
Low cost (withhuge subsidies)
Coal Nuclear
Trade-Offs
Nuclear Power Is Vulnerable toTerrorist Acts
• Insufficient security
• On-site storage facilities
• U.S.: 161 million people live within 75 miles of an above-ground nuclear storage site
Dealing with Radioactive Wastes
• High-level radioactive wastes
• Long-term storage: 10,000–240,000 years
• Deep burial
• Detoxify wastes?
Case Study: Dealing with Radioactive Wastes in the United States
• Yucca Mountain, Nevada
• Concerns over groundwater contamination
• Possible seismic activity
• Transportation accidents and terrorism
• 2009: Obama ends Yucca funding
What Do We Do with Worn-Out Nuclear Power Plants?
• Decommissioning old nuclear power plants
• Dismantle power plant and store materials
• Install physical barriers
• Entomb entire plant
What Is the Future for Nuclear Power?
• Reduce dependence on foreign oil
• Reduce global warming
• Advanced light-water reactors
• Nuclear fusion
• How to develop relatively safe nuclear power with a high net energy yield?
13-4 Why Is Energy Efficiency an Important Energy Source?
• Concept 13-4 The United States could save as much as 43% of all the energy it uses by improving the energy efficiency of industrial operations, motor vehicles, and buildings.
Improving Energy Efficiency
• Energy efficiency– How much work we get from each unit
of energy we use
• Reducing energy waste– 41% of all commercial energy in U.S. is
wasted unnecessarily
• Numerous economic and environmental advantages
OutputsSystemEnergy Inputs
43%
7%
9%
3%4%
41%85%
8%
U.S.economy
Fig. 13-19, p. 319
Nonrenewable fossil fuels
Nonrenewable nuclear
Hydropower, geothermal,Wind, solarBiomasss
Useful energy
Petrochemicals
Unavoidable energywasteUnnecessary energy
Examples of Energy-Wasting Devices
• Incandescent light bulb
• Internal combustion engine
• Nuclear power plants
• Coal-burning power plants
Saving Energy and Money in Industry
• Cogeneration/Combined Heat and Power (CHP) systems
• Recycling
• Energy-saving electric motors
• Fluorescent lighting
• Smart grid electricity
Saving Energy and Money in Transportation
• 2/3 of U.S. oil consumption
• Low fuel-efficiency standards for vehicles
• Hidden costs: $12/gallon of gas
• Raise gasoline taxes/cut payroll and income taxes
• Tax breaks for fuel-efficient vehicles
Hybrid and Fuel-Cell Cars
• Super-efficient and ultralight cars
• Gasoline-electric hybrid car
• Plug-in hybrid electric car
• Hydrogen fuel cells
• Accessible mass-transit systems as alternative
Stepped Art
Fig. 13-21, p. 320
25Cars
20 Cars, trucks, and SUVs
Trucks and SUVs15
Ave
rag
e f
uel
eco
no
my
(mil
es
per
gal
lon
)
10
1975 1980 1985 1990 1995 2000 2005
Year
50
45 Europe
40 Japan
35China
Mil
es p
er g
allo
n (
mp
g)
(co
nve
rted
to
U.S
. te
st e
qu
ival
ents
)
30 Canada
25United States20
2002 2004 2006 2008
Year
Stepped Art
Conventional hybrid Fuel tank
Battery
Internal combustion engine
Transmission Electric motor
Plug-in hybrid
Fuel tank
Battery
Internal combustion engine
Transmission Electric motor
Fig. 13-22, p. 321
Saving Energy and Money in New Buildings
• Green architecture
• Solar cells, fuel cells, eco-roofs, recycled materials
• Super insulation
• Straw bale houses
Saving Energy in Existing Buildings
• Insulate and plug leaks
• Use energy-efficient windows
• Heat houses more efficiently
• Heat water more efficiently
• Use energy-efficient appliances
• Use energy-efficient lighting
Fig. 13-23, p. 322
Fig. 13-24, p. 324
Outside Plant deciduous trees to blocksummer sun and let in wintersunlight.
Other rooms • Use compact fluorescent lightbulbs or LEDs and avoid using incandescent bulbs wherever possible.• Turn off lights, computers, TV, and other electronic devices when they are not in use.• Use high efficiency windows; use insulating window covers and close them at night and on sunny, hot days.• Set thermostat as low as you can in winter and as high as you can in summer.• Weather-strip and caulk doors, windows, light fixtures, and wall sockets.• Keep heating and cooling vents free of obstructions.• Keep fireplace damper closed when not in use.• Use fans instead of, or along with, air conditioning.
Bathroom• Install water-saving toilets, faucets, and shower heads.• Repair water leaks promptly.
Stepped Art
Attic• Hang reflective foil near roof to reflect heat.• Use house fan.• Be sure attic insulation is at least 30 centimeters (12 inches).
Kitchen• Use microwave rather than stove or oven as much as possible.• Run only full loads in dishwasher and use low- or no-heat drying.• Clean refrigerator coils regularly.
Basement or utility room • Use front-loading clothes washer. If possible run only full loads with warm or cold water.
• Hang clothes on racks for drying.• Run only full loads in clothes dryer and use lower heat setting.• Set water heater at 140° if dishwasher is used and 120° or lower if no dishwasher is used.
• Use water heater thermal blanket.• Insulate exposed hot water pipes.• Regularly clean or replace furnace filters.
Why Are We Still Wasting So Much Energy?
• Energy costs relatively little
• Lack of government support and economic incentives
• Inadequate building codes
• Inadequate appliance standards
• Lack of information about saving energy
13-5 What Are Advantages/Disadvantages of Renewable Energy Resources?
• Concept 13-5 Using a mix of renewable energy sources – especially sunlight, wind, flowing water, sustainable biomass, and geothermal energy – can drastically reduce pollution, greenhouse gas emissions, and biodiversity losses.
Renewable Energy
• Sustainability mostly depends on solar energy– Direct form: from the sun
• Indirect forms– Wind– Moving water– Biomass
• Geothermal
Benefits of Shifting to Renewable Energy Resources (1)
• More decentralized, less vulnerable
• Improve national security
• Reduce trade deficits
• Reduce air pollution
Benefits of Shifting to Renewable Energy Resources (2)
• Create jobs
• Save money
• Renewable energy handicapped by– Unbalanced, intermittent subsidies
– Inaccurate pricing
Using Solar Energy to Heat Buildings and Water
• Passive solar heating system
• Active solar heating system
Fig. 13-25, p. 325
Fig. 13-25, p. 325
PASSIVE
Summersun
Wintersun
Vent allowshot air toescape insummer
Superwindow
Superwindow
Stone floor and wall for heat storage
Heavyinsulation
Fig. 13-25, p. 325
Supplement 9, Fig. 5, p. S41
Fig. 13-26, p. 326
Passive or Active Solar Heating
Need access to sun 60%of time
Sun can be blocked bytrees and other structures
Environmental costs notincluded in market price
Need heat storage system
High cost (active)
Active system needsmaintenance and repair
Active collectorsunattractive
Energy is free
Net energy is moderate(active) to high (passive)
Quick installation
No CO2 emissions
Very low air and waterpollution
Very low land disturbance(built into roof or windows)
Moderate cost (passive)
Advantages Disadvantages
Trade-Offs
Solar Energy for High-Temperature Heat and Electricity• Solar thermal systems
• Solar thermal plant
• Solar cookers
• Photovoltaic (solar) cells
Fig. 13-27, p. 326
Trade-Offs
Low efficiency
Low net energy
High costs
Environmental costs notincluded in market price
Needs backup or storagesystem
Needs access to sun most ofthe time
May disturb desert areas
Costs reduced withnatural gas turbinebackup
No CO2 emissions
Fast construction(1–2 years)
Moderate environmentalimpact
Advantages Disadvantages
Solar Energy for High-TemperatureHeat and Electricity
Boron-enrichedsilicon
Phosphorus-enriched silicon
Junction
Single solar cell Solar-cell roof
Panels of solar cells
Solar shingles
Roof options
Fig. 13-29, p. 328
Fig. 13-30, p. 328
Fig. 13-31, p. 328
Solar Cells
Need access to sun
Low efficiency
Need electricity storagesystem or backup
Environmental costs notincluded in market price
High costs (but should be competitive in 5–15 years)
High land use (solar-cellpower plants) coulddisrupt desert areas
DC current must beconverted to AC
Reduces dependence onfossil fuels
Low land use (if on roof orbuilt into walls or windows)
Last 20–40 years
Low environmental impact
No CO2 emissions
Easily expanded or moved
Quick installation
Work on cloudy days
Fairly high net energy yield
Trade-Offs
DisadvantagesAdvantages
Producing Electricity from Flowing Water
• Hydropower– Leading renewable energy source
– Much unused capacity
• Dams and reservoirs– Turbines generate electricity
– Eventually fill with silt
• Micro-hydro generators
Fig. 13-32, p. 329
Large-Scale Hydropower
High construction costs
High environmentalimpact from flooding landto form a reservoir
Environmental costs notincluded in market price
High CH4 emissions fromrapid biomass decay inshallow tropical reservoirs
Danger of collapse
Uproots people
Decreases fish harvestbelow dam
Decreases flow of naturalfertilizer (silt) to landbelow dam
Moderate to high net energy
High efficiency (80%)
Large untapped potential
Low-cost electricity
Long life span
No CO2 emissions duringoperation in temperate areas
Can provide flood controlbelow dam
Provides irrigation water
Reservoir useful for fishingand recreation
DisadvantagesAdvantages
Trade-Offs
Producing Electricity from Wind
• Indirect form of solar energy
• World’s second fastest-growing source of energy
• Vast potential– Land
– Offshore
Supplement 9, Fig. 8, p. S43
Fig. 13-34, p. 331
Trade-Offs
Steady winds needed
Backup systems needed whenwinds are low
Plastic components producedfrom oil
Environmental costs notincluded in market price
High land use for wind farm
Visual pollution
Noise when located nearpopulated areas
Can kill birds and interferewith flights of migratory birdsif not sited properly
Moderate to high netenergy yield
High efficiency
Moderate capital cost
Low electricity cost (andfalling)
Very low environmentalimpact
No CO2 emissions
Quick construction
Easily expanded
Can be located at sea
Land below turbines canbe used to grow crops orgraze livestock
Advantages Disadvantages
Wind Power
Energy from Burning Biomass
• Biomass– Wood
– Agricultural waste
– Plantations
– Charcoal
– Animal manure
• Common in developing countries• Carbon dioxide increase in atmosphere
Converting Plant Matter to Liquid Biofuel
• Biofuels– Ethanol and biodiesel
– Crops can be grown in most countries
– No net increase in carbon dioxide emissions
– Available now
• Sustainability
Fig. 13-35, p. 333
Increased NOx emissionsand more smog
Higher cost thanregular diesel
Environmental costs notincluded in market price
Low net energy yield forsoybean crops
May compete withgrowing food oncropland and raise foodprices
Loss and degradation ofbiodiversity from cropplantations
Can make engines hardto start in cold weather
Reduced COemissions
Reduced CO2
emissions (78%)
High net energyyield for oil palmcrops
Moderate netenergy yield forrapeseed crops
Reducedhydrocarbonemissions
Better gasmileage (40%)
Potentiallyrenewable
Trade-Offs
Advantages Disadvantages
Biodiesel
Fig. 13-36, p. 334
Fig. 13-37, p. 335
Lower driving range
Low net energy yield (corn)
Higher CO2 emissions (corn)
Much higher cost
Environmental costs notincluded in market price
May compete with growingfood and raise food prices
Higher NOx emissions andmore smog
Corrosive
Can make engines hard tostart in cold weather
High octane
Some reduction in CO2
emissions(sugarcane bagasse)
High net energy yield(bagasse and switchgrass)
Can be sold as a mixture ofgasoline and ethanol or aspure ethanol
Potentially renewable
Trade-Offs
Advantages Disadvantages
Ethanol Fuel
http://articles.cnn.com/2008-04-01/tech/algae.oil_1_algae-research-fossil-fuels-nrel?_s=PM:TECH
Energy by Tapping the Earth’s Internal Heat
• Geothermal energy
• Geothermal heat pumps
• Hydrothermal reservoirs– Steam
– Hot water
• Deep geothermal energy
Supplement 9, Fig. 9, p. S43
Supplement 9, Fig. 10, p. S44
Fig. 13-38, p. 336
Very high efficiency Scarcity of suitable sites
Can be depleted if used toorapidly
Environmental costs notincluded in market price
CO2 emissions
Moderate to high local airpollution
Noise and odor (H2S)
High cost except at the mostconcentrated and accessiblesources
Moderate environmentalimpact
Low land use anddisturbance
Low cost at favorable sites
Lower CO2 emissions thanfossil fuels
Moderate net energy ataccessible sites
Trade-Offs
Advantages Disadvantages
Geothermal Energy
Can Hydrogen Replace Oil?
• Hydrogen is environmentally friendly• Problems
– Most hydrogen is in water– Net energy yield is negative– Fuel is expensive– Air pollution depends on production
method– Storage
Fig. 13-39, p. 337
Not found as H2 in nature
Energy is needed to produce fuel
Negative net energy
CO2 emissions if produced fromcarbon-containing compounds
Environmental costs not includedin market price
Nonrenewable if generated byfossil fuels or nuclear power
High costs (that may eventuallycome down)
Will take 25 to 50 years tophase in
Short driving range for currentfuel-cell cars
No fuel distribution systemin place
Excessive H2 leaks may depleteozone in the atmosphere
Can be produced fromplentiful water
Low environmental impact
Renewable if producedfrom renewable energyresources
No CO2 emissions ifproduced from water
Good substitute for oil
Competitive price ifenvironmental and socialcosts are included in costcomparisons
Easier to store thanelectricity
Safer than gasoline andnatural gas
Nontoxic
High efficiency (45–65%)in fuel cells
Trade-Offs
Advantages Disadvantages
Hydrogen
Fuelcell
Science Focus: The Quest to Make Hydrogen Workable
• Bacteria and Algae
• Electricity from solar, wind, geothermal
• Storage: liquid and solid
• Preventing explosions
13-6 How Can We Make the Transition to a More Sustainable Energy Future?
• Concept 13-6 We can make a transition to a more sustainable energy future by greatly improving energy efficiency, using a mix of renewable energy resources, and including environmental costs of energy resources in their market prices.
Transition to a More Sustainable Energy Future (1)
• For each energy alternative:– How much available next 25-50 years?– Estimated net energy yield– Total costs– Necessary subsidies and tax breaks– How affect economic and military security– Vulnerability to terrorism– Environmental effects
Bioenergy power plants
Smart electricaland distributionsystem
Small solar-cellpower plants
Solar-cellrooftopsystems
Commercial
Fuel cells
Rooftop solar-cell arrays
Residential
Small windturbine
Stepped ArtIndustrial Microturbines
Wind farm
Fig. 13-40, p. 339
Decentralized Power System
Transition to a More Sustainable Energy Future (2)
• Gradual shift from centralized macropower to decentralized micropower
• Greatly improved energy efficiency
• Temporary use of natural gas
• Decrease environmental impact of fossil fuels
Fig. 13-41, p. 340
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Mandate government purchases of efficient vehicles and other devices
Provide large tax credits or feebates for buying efficient cars, houses, and appliances
Offer large tax credits for investments in energy efficiency
Reward utilities for reducing demand for electricity
Greatly increase energy efficiency research and development
Improve Energy Efficiency
Making the Transition to a More Sustainable Energy Future
Solutions
Phase out nuclear power subsidies, tax breaks, and loan guarantees
More Renewable Energy
Greatly increase use of renewable energy
Provide large subsidies and tax credits for use of renewable energy
Include environmental costs in prices for all energy resources
Encourage government purchase of renewable energy
Greatly increase renewable energy research and development
Reduce Pollution and Health Risk
Cut coal use 50% by 2020
Phase out coal subsidies and tax breaks
Levy taxes on coal and oil use
Economic, Political, and Educational Strategies to Sustainable Energy
• Requires government strategies
• Keep prices low in selected resource to encourage use– Same strategy for fossil fuels and nuclear
power
• Keep prices high in selected resource to discourage use
• Emphasize consumer education
Three Big Ideas from This Chapter - #1
Energy resources should be evaluated on the basis of their potential supplies, how much net useful energy they provide, and the environmental impact of using them.
Three Big Ideas from This Chapter - #2
Using a mix of renewable energy – especially sunlight, wind, flowing water, sustainable biofuels, and geothermal energy – can drastically reduce pollution, greenhouse gas emissions, and biodiversity losses.
Three Big Ideas from This Chapter - #3
Making the transition to a more sustainable energy future requires sharply reducing energy waste, using a mix of environmentally friendly renewable energy resources, and including the harmful environmental costs of energy resources in their market prices.