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What is renewable energy?

Energy exists freely in nature. Some of them exist infinitely never run out, called RENEWABLE

With this in mind, it is a lot easier to lay any type of energy source in its' right place. Let's look at these

types of energy in the diagram below:

You will notice that water, wind, sun and biomass (vegetation) are all available naturally and were not

formed. The others do not exist by themselves, they were formed. Renewable energy resources are

always available to be tapped, and will not run out. This is why some people call it Green Energy

Renewable energy includes Biomass, Wind, Hydro-power, Geothermal and Solar sources. Renewable

energy can be converted to electricity, which is stored and transported to our homes for use. In this

lesson, we shall take a closer look at how renewable energy is converted into electricity.

Types of Renewable Energy

Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar energy, can

be used directly for heating and lighting homes and other buildings, for generating electricity, and for

hot water heating, solar cooling, and a variety of commercial and

industrial uses.

The sun's heat also drives the winds, whose energy, is captured with wind

turbine. Then, the winds and the sun's heat cause water to evaporate.

When this water vapor turns into rain or snow and flows downhill into

rivers or streams, its energy can be captured using hydroelectric power.

Along with the rain and snow, sunlight causes plants to grow. The organic

matter that makes up those plants is known as biomass. Biomass can be

used to produce electricity, transportation fuels, or chemicals.

Solar shingles

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The use of biomass for any of these purposes is called bioenergy.

Hydrogen also can be found in many organic compounds, as well as water. It's the most abundant

element on the Earth. But it doesn't occur naturally as a gas. It's always combined with other elements,

such as with oxygen to make water. Once separated from another element, hydrogen can be burned as

a fuel or converted into electricity.

Not all renewable energy resources come from the sun. Geothermal energy taps the Earth's internal

heat for a variety of uses, including electric power production, and the heating and cooling of buildings.

And the energy of the ocean's tides come from the gravitational pull of the moon and the sun upon the

Earth.

In fact, ocean energy comes from a number of sources. In addition to tidal energy, there's the energy of

the ocean's waves, which are driven by both the tides and the winds. The sun also warms the surface of

the ocean more than the ocean depths, creating a temperature difference that can be used as an energy

source. All these forms of ocean energy can be used to produce electricity.

Why Is Renewable Energy Important?

Renewable energy is important because of the benefits it provides.

The key benefits are:

Environmental Benefits

Renewable energy technologies are clean sources of energy that have

a much lower environmental impact than conventional energy

technologies.

eNERGY fOR oUR cHILDREN'S cHILDREN'S cHILDREN

Renewable energy will not run out forever. Other sources of energy are finite and will some day be

depleted.

Jobs and the Economy

Most renewable energy investments are spent on materials and workmanship to build and maintain the

facilities, rather than on costly energy imports. Renewable energy investments are usually spent within

the United States, frequently in the same state, and often in the same town. This means your energy

dollars stay home to create jobs and fuel local economies, rather than going overseas. Meanwhile,

renewable energy technologies developed and built in the United States are being sold overseas,

providing a boost to the U.S. trade deficit.

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Energy Security

After the oil supply disruptions of the early 1970s, our nation has increased its dependence on foreign

oil supplies instead of decreasing it. This increased dependence impacts more than just our national

energy policy.

SOLAR ENERGY

Solar energy technologies use the sun's energy and light to provide heat, light, hot water, electricity, and

even cooling, for homes, businesses, and industry.

Solar power is energy from the sun. "Solar" is the Latin word for "sun" and it's a powerful source of

energy. Without it, there will be no life. Solar energy is considered as a serious source of energy for

many years because of the vast amounts of energy that are made freely available, if harnessed by

modern technology.

Solar cells

Solar cells are devices that convert light energy directly into electrical energy. You may have seen small

solar cells on calculators. Larger arrays of solar cells are used to power road signs, and even larger arrays

are used to power satellites in orbit around Earth. Solar cells are also called photovoltaic cells.

Solar panels

Solar panels are different to solar cells. Solar panels do not generate electricity. Instead they heat up

water directly. A pump pushes cold water from a storage tank through pipes in the solar panel. The

water is heated by heat energy from the Sun and returns to the tank. They are often located on the

roofs of buildings where they can receive the most sunlight.

Solar power

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There are a variety of technologies that have been developed to take advantage of solar energy. These

include:

Photovoltaic Systems - Producing electricity directly from sunlight.

Solar cells convert sunlight directly into electricity. Solar cells are often used to power calculators and

watches. They are made of semiconducting materials similar to those used in computer chips. When

sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms,

allowing the electrons to flow through the material to produce electricity. This process of converting

light (photons) to electricity (voltage) is called the photovoltaic (PV) effect.

Solar cells are typically combined into modules that hold about 40 cells; a number of these modules are

mounted in PV arrays that can measure up to several meters on a side. These flat-plate PV arrays can be

mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun,

allowing them to capture the most sunlight over the course of a day. Several connected PV arrays can

provide enough power for a household; for large electric utility or industrial applications, hundreds of

arrays can be interconnected to form a single, large PV system.

Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Thin film

technology has made it possible for solar cells to now double as rooftop shingles, roof tiles, building

facades, or the glazing for skylights or atria. The solar cell version of items such as shingles offer the

same protection and durability as ordinary asphalt shingles.

Some solar cells are designed to operate with concentrated sunlight. These cells are built into

concentrating collectors that use a lens to focus the sunlight onto the cells. This approach has both

advantages and disadvantages compared with flat-plate PV arrays. The main idea is to use very little of

the expensive semiconducting PV material while collecting as much sunlight as possible. But because the

lenses must be pointed at the sun, the use of concentrating collectors is limited to the sunniest parts of

the country. Some concentrating collectors are designed to be mounted on simple tracking devices, but

most require sophisticated tracking devices, which further limit their use to electric utilities, industries,

and large buildings.

The performance of a solar cell is measured in terms of its efficiency at turning sunlight into electricity.

Only sunlight of certain energies will work efficiently to create electricity, and much of it is reflected or

absorbed by the material that makes up the cell. Because of this, a typical commercial solar cell has an

efficiency of 15%-about one-sixth of the sunlight striking the cell generates electricity. Low efficiencies

mean that larger arrays are needed, and that means higher cost. Improving solar cell efficiencies while

holding down the cost per cell is an important goal of the PV industry, NREL researchers, and other U.S.

Department of Energy (DOE) laboratories, and they have made significant progress. The first solar cells,

built in the 1950s, had efficiencies of less than 4%.

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Solar Hot Water - Heating water

with solar energy.

The shallow water of a lake is

usually warmer than the deep

water. That's because the sunlight

can heat the lake bottom in the

shallow areas, which in turn, heats

the water. It's nature's way of solar

water heating. The sun can be used in basically the same way to heat

water used in buildings and swimming pools.

Most solar water heating systems for buildings have two main parts: a solar collector and a storage tank.

The most common collector is called a flat-plate collector. Mounted on the roof, it consists of a thin, flat,

rectangular box with a transparent cover that faces the sun. Small tubes run through the box and carry

the fluid – either water or other fluid, such as an antifreeze solution – to be heated. The tubes are

attached to an absorber plate, which is painted black to absorb the heat. As heat builds up in the

collector, it heats the fluid passing through the tubes.

The storage tank then holds the hot liquid. It can be just a modified water heater, but it is usually larger

and very well-insulated. Systems that use fluids other than water usually heat the water by passing it

through a coil of tubing in the tank, which is full of hot fluid.

Solar water heating systems can be either active or passive, but the most common are active systems.

Active systems rely on pumps to move the liquid between the collector and the storage tank, while

passive systems rely on gravity and the tendency for water to naturally circulate as it is heated.

Swimming pool systems are simpler. The pool's filter pump is used to pump the water through a solar

collector, which is usually made of black plastic or rubber. And of course, the pool stores the hot water.

Solar Electricity - Using the sun's heat to produce electricity.

Many power plants today use fossil fuels as a heat source to boil water. The steam from the boiling

water rotates a large turbine, which activates a generator that produces electricity. However, a new

generation of power plants, with concentrating solar power systems, uses the sun as a heat source.

There are three main types of concentrating solar power systems: parabolic-trough, dish/engine, and

power tower.

Parabolic-trough systems concentrate the sun's energy through long rectangular, curved (U-shaped)

mirrors. The mirrors are tilted toward the sun, focusing sunlight on a pipe that runs down the center of

the trough. This heats the oil flowing through the pipe. The hot oil then is used to boil water in a

conventional steam generator to produce electricity.

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A dish/engine system uses a mirrored dish (similar to a very large satellite dish). The dish-shaped surface

collects and concentrates the sun's heat onto a receiver, which absorbs the heat and transfers it to fluid

within the engine. The heat causes the fluid to expand against a piston or turbine to produce mechanical

power. The mechanical power is then used to run a generator or alternator to produce electricity.

A power tower system uses a large field of mirrors to concentrate sunlight onto the top of a tower,

where a receiver sits. This heats molten salt flowing through the receiver. Then, the salt's heat is used to

generate electricity through a conventional steam generator. Molten salt retains heat efficiently, so it

can be stored for days before being converted into electricity. That means electricity can be produced

on cloudy days or even several hours after sunset.

Passive Solar Heating and Day lighting - Using solar energy to heat and light buildings.

Step outside on a hot and sunny summer day, and you'll feel the power of solar heat and light. Today,

many buildings are designed to take advantage of this natural resource through the use of passive solar

heating and day lighting.

The south side of a building always receives the most sunlight. Therefore, buildings designed for passive

solar heating usually have large, south-facing windows. Materials that absorb and store the sun's heat

can be built into the sunlit floors and walls. The floors and walls will then heat up during the day and

slowly release heat at night, when the heat is needed most. This passive solar design feature is called

direct gain. Other passive solar heating design features include sunspaces and trombe walls. A sunspace

(which is much like a greenhouse) is built on the south side of a building. As sunlight passes through

glass or other glazing, it warms the sunspace. Proper ventilation allows the heat to circulate into the

building. On the other hand, a trombe wall is a very thick, south-facing wall, which is painted black and

made of a material that absorbs a lot of heat. A pane of glass or plastic glazing, installed a few inches in

front of the wall, helps hold in the heat. The wall heats up slowly during the day. Then as it cools

gradually during the night, it gives off its heat inside the building.

Many of the passive solar heating design features also provide day lighting. Day lighting is simply the

use of natural sunlight to brighten up a building's interior. To lighten up north-facing rooms and upper

levels, a clerestory - a row of windows near the peak of the roof - is often used along with an open floor

plan inside that allows the light to bounce throughout the building.

Thousands of years ago, the Anasazi Indians in Colorado

incorporated passive solar design in their cliff dwellings.

Of course, too much solar heating and day lighting can be a problem

during the hot summer months. Fortunately, there are many design

features that help keep passive solar buildings cool in the summer.

For instance, overhangs can be designed to shade windows when

the sun is high in the summer. Sunspaces can be closed off from the

rest of the building. And a building can be designed to use fresh-air

ventilation in the summer.

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Solar Process Space Heating and Cooling -Industrial and commercial uses of the sun's heat

Commercial and industrial buildings may use the same solar technologies - photovoltaic, passive

heating, day lighting, and water heating - that are used for residential buildings. These nonresidential

buildings can also use solar energy technologies that would be impractical for a home. These

technologies include ventilation air preheating, solar process heating, and solar cooling.

Many large buildings need ventilated air to maintain indoor air quality. In cold climates, heating this air

can use large amounts of energy. A solar ventilation system can preheat the air, saving both energy and

money. This type of system typically uses a transpired collector, which consists of a thin, black metal

panel mounted on a south-facing wall to absorb the sun's heat. Air passes through the many small holes

in the panel. A space behind the perforated wall allows the air streams from the holes to mix together.

The heated air is then sucked out from the top of the space into the ventilation system.

Solar process heating systems are designed to provide large quantities of hot water or space heating for

nonresidential buildings. A typical system includes solar collectors that work along with a pump, a heat

exchanger, and/or one or more large storage tanks. The two main types of solar collectors used - an

evacuated-tube collector and a parabolic-trough collector - can operate at high temperatures with high

efficiency. An evacuated-tube collector is a shallow box full of many glass, double-walled tubes and

reflectors to heat the fluid inside the tubes. A vacuum between the two walls insulates the inner tube,

holding in the heat. Parabolic troughs are long, rectangular, curved (U-shaped) mirrors tilted to focus

sunlight on a tube, which runs down the center of the trough. This heats the fluid within the tube.

The heat from a solar collector can also be used to cool a building. It may

seem impossible to use heat to cool a building, but it makes more sense if

you just think of the solar heat as an energy source. Your familiar home air

conditioner uses an energy source, electricity, to create cool air. Solar

absorption coolers use a similar approach, combined with some very

complex chemistry tricks, to create cool air from solar energy. Solar energy

can also be used with evaporative coolers (also called "swamp coolers") to

extend their usefulness to more humid climates, using another chemistry

trick called desiccant cooling.

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Wind Power

Wind is caused by huge convection currents in the Earth's atmosphere,

driven by heat energy from the Sun. This means as long as the sun shines,

there will be wind.

The moving air (wind) has huge amounts of kinetic energy, and this can

be transferred into electrical energy using wind turbines. The wind turns

the blades, which spin a shaft, which connects to a generator and makes

electricity. The electricity is sent through transmission and distribution

lines to a substation, then on to homes, business and schools.

Wind turbines cannot work if there is no wind,

or if the wind speed is so high it would damage them.

Wind turbines are usually sited on high hills and mountain ridges to take

advantage of the prevailing winds.

Just like a windmill, wind energy turbines have been around for over

1000 years. From old Holland to farms in the United States, windmills

have been used for pumping water or grinding grain.

Did you know...?

The largest wind turbine in the world, located in

Hawaii, stands 20 stories tall and has blades the length of a

football field.

An average wind speed of 14

miles per hour is needed to

convert wind energy into

electricity.

One wind turbine can

produce enough electricity

to power up to 300 homes.

The first power generating

turbine was constructed in

Ohio during the late 1800's

and was used to charge

batteries.

Wind energy is the fastest

growing segment of all

renewable energy sources.

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We have been harnessing the wind's energy for hundreds of

years. Today, the windmill's modern equivalent - a wind turbine

- can use the wind's energy to generate electricity.

Wind turbines, like windmills, are mounted on a tower to

capture the most energy. At 100 feet (30 meters) or more

aboveground, they can take advantage of the faster and less

turbulent wind. Turbines catch the wind's energy with their

propeller-like blades. Usually, two or three blades are mounted

on a shaft to form a rotor.

Modern wind turbines tower above one of their ancestors-an old windmill used for pumping water.

Credit: Warren Gretz

A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on

the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the

rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force

against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor

to spin like a propeller, and the turning shaft spins a generator to make electricity.

Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid

or even combined with a photovoltaic (solar cell) system. For utility-scale sources of wind energy, a large

number of wind turbines are usually built close together to form a wind plant. Several electricity

providers today use wind plants to supply power to their customers.

Stand-alone wind turbines are typically used for water pumping or communications. However,

homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their

electric bills.

Small wind systems also have potential as distributed energy resources. Distributed energy resources

refer to a variety of small, modular power-generating technologies that can be combined to improve the

operation of the electricity delivery system.

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Geothermal

In some places the rocks underground are hot. Deep wells can be drilled and cold water pumped down.

The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water

and steam, where its' energy can be used to drive turbines and electricity generators.

Geothermal energy is called a renewable energy source because the water is replenished by rainfall, and

the heat is continuously produced by the earth. Geothermal energy is the heat from the Earth. It's clean

and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot

rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high

temperatures of molten rock called magma.

Almost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly

constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this

resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air

delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near

the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the

indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from

the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can

also be used to provide a free source of hot water.

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The Earth's heat-called geothermal energy-escapes as steam at a hot

springs in Nevada.

In the United States, most geothermal reservoirs of hot water are

located in the western states, Alaska, and Hawaii. Wells can be drilled

into underground reservoirs for the generation of electricity. Some

geothermal power plants use the steam from a reservoir to power a

turbine/generator, while others use the hot water to boil a working

fluid that vaporizes and then turns a turbine. Hot water near the

surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing

plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as

pasteurizing milk.

Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth's surface and at

lesser depths in certain areas. Access to these resources involves injecting cold water down one well,

circulating it through hot fractured rock, and drawing off the heated water from another well. Currently,

there are no commercial applications of this technology. Existing technology also does not yet allow

recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.

Many technologies have been developed to take advantage of geothermal energy - the heat from the

earth.

Geothermal Electricity Production - Generating electricity from the earth's heat.

Most power plants need steam to generate electricity. The steam rotates a turbine that activates a

generator, which produces electricity. Many power plants still use fossil fuels to boil water for steam.

Geothermal power plants, however, use steam produced from reservoirs of hot water found a couple of

miles or more below the Earth's surface. There are three types of geothermal power plants: dry steam,

flash steam, and binary cycle.

Dry steam power plants draw from underground resources of steam. The steam is piped directly from

underground wells to the power plant, where it is directed into a turbine/generator unit. There are only

two known underground resources of steam in the United States: The Geysers in northern California and

Yellowstone National Park in Wyoming, where there's a well-known geyser called Old Faithful. Since

Yellowstone is protected from development, the only dry steam plants in the country are at The

Geysers.

This geothermal power plant generates electricity for the Imperial

Valley in California.

Flash steam power plants are the most common. They use geothermal

reservoirs of water with temperatures greater than 360°F (182°C).

This very hot water flows up through wells in the ground under its

own pressure. As it flows upward, the pressure decreases and some of

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the hot water boils into steam. The steam is then separated from the water and used to power a

turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, making

this a sustainable resource.

Binary cycle power plants operate on water at lower temperatures of about 225°-360°F (107°-182°C).

These plants use the heat from the hot water to boil a working fluid, usually an organic compound with

a low boiling point. The working fluid is vaporized in a heat exchanger and used to turn a turbine. The

water is then injected back into the ground to be reheated. The water and the working fluid are kept

separated during the whole process, so there are little or no air emissions.

Small-scale geothermal power plants (under 5 megawatts) have the potential for widespread application

in rural areas, possibly even as distributed energy resources. Distributed energy resources refer to a

variety of small, modular power-generating technologies that can be combined to improve the

operation of the electricity delivery system.

In the United States, most geothermal reservoirs are located in the western states, Alaska, and Hawaii.

Geothermal Direct Use - Producing heat directly from hot water within the earth.

When a person takes a hot bath, the heat from the water will usually warm up the entire bathroom.

Geothermal reservoirs of hot water, which are found a couple of miles or more beneath the Earth's

surface, can also be used to provide heat directly. This is called the direct use of geothermal energy.

Geothermal direct use dates back thousands of years, when people began using hot springs for bathing,

cooking food, and loosening feathers and skin from game. Today, hot springs are still used as spas. But

there are now more sophisticated ways of using this geothermal resource.

In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of

hot water. The water is brought up through the well, and a mechanical system - piping, a heat

exchanger, and controls - delivers the heat directly for its intended use. A disposal system then either

injects the cooled water underground or disposes of it on the surface.

Geothermal hot water can be used for many applications that require

heat. Its current uses include heating buildings (either individually or

whole towns), raising plants in greenhouses, drying crops, heating

water at fish farms, and several industrial processes, such as

pasteurizing milk. With some applications, researchers are exploring

ways to effectively use the geothermal fluid for generating electricity

as well.

Geothermal heated waters allow alligators to thrive on a farm in

Colorado, where temperatures can drop below freezing.

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Geothermal Heat Pumps - Using the shallow ground to heat and cool

buildings.

The shallow ground, the upper 10 feet of the Earth, maintains a nearly

constant temperature between 50° and 60°F (10°-16°C). Like a cave,

this ground temperature is warmer than the air above it in the winter

and cooler than the air in the summer. Geothermal heat pumps take

advantage of this resource to heat and cool buildings.

The West Philadelphia Enterprise Center uses a geothermal heat pump system for more than 31,000

square feet of space. Credit: Geothermal Heat Pump Consortium

Geothermal heat pump systems consist of basically three parts: the ground heat exchanger, the heat

pump unit, and the air delivery system (ductwork). The heat exchanger is basically a system of pipes

called a loop, which is buried in the shallow ground near the building. A fluid (usually water or a mixture

of water and antifreeze) circulates through the pipes to absorb or relinquish heat within the ground.

In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air

delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor

air into the heat exchanger. The heat removed from the indoor air during the summer can also be used

to heat water, providing a free source of hot water.

Geothermal heat pumps use much less energy than conventional heating systems, since they draw heat

from the ground. They are also more efficient when cooling your home. Not only does this save energy

and money, it reduces air pollution.

All areas of the United States have nearly constant shallow-ground temperatures, which are suitable for

geothermal heat pumps.

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Biomass

Biomass fuels come from living things: wood products, dried vegetation, crop residues, and aquatic

plants. Wood is a biomass fuel. As long as we continue to plant new trees to replace those cut down, we

will always have wood to burn. Just as with the fossil fuels, the energy stored in biomass fuels came

originally from the Sun.

It is such a widely utilized source of energy, probably due to its low cost and indigenous nature, that it

accounts for almost 15% of the world's total energy supply and as much as 35% in developing countries,

mostly for cooking and heating.

Electricity can also be generated from Biomass and stored to be used in homes. Let's see this simple

illustration of how biomass is used to generate electricity.

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Bioenergy

We have used biomass

energy or bioenergy - the

energy from organic

matter - for thousands of

years, ever since people

started burning wood to

cook food or to keep

warm.

Corn can be harvested to produce ethanol.

And today, wood is still our largest biomass energy resource.

But many other sources of biomass can now be used,

including plants, residues from agriculture or forestry, and

the organic component of municipal and industrial wastes.

Even the fumes from landfills can be used as a biomass

energy source.

The use of biomass energy has the potential to greatly

reduce our greenhouse gas emissions. Biomass generates

about the same amount of carbon dioxide as fossil fuels, but

every time a new plant grows, carbon dioxide is actually

removed from the atmosphere. The net emission of carbon

dioxide will be zero as long as plants continue to be

replenished for biomass energy purposes.

These energy crops, such as fast-growing trees and grasses, are called biomass feedstock. The use of

biomass feedstock can also help increase profits for the agricultural industry.

There are three major biomass energy technology applications:

Biofuels - Converting biomass into liquid fuels for transportation.

Unlike other renewable energy sources, biomass can be converted directly into liquid fuels - biofuels -

for our transportation needs (cars, trucks, buses, airplanes, and

trains). The two most common types of biofuels are ethanol and

biodiesel.

Ethanol is an alcohol, the same found in beer and wine. It is made by

fermenting any biomass high in carbohydrates (starches, sugars, or

celluloses) through a process similar to brewing beer. Ethanol is

mostly used as a fuel additive to cut down a vehicle's carbon

monoxide and other smog-causing emissions. But flexible-fuel

1. Energy from the sun is transferred and

stored in plants. When the plants are cut

or die, wood chips, straw and other plant

matter is delivered to the bunker

2. This is burned to heat water in a boiler

to release heat energy (steam).

3. The energy/power from the steam is

directed to turbines with pipes

4. The steam turns a number of blades in

the turbine and generators, which are

made of coils and magnets.

5. The charged magnetic feilds produce

electricity, which is sent to homes by

cables

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vehicles, which run on mixtures of gasoline and up to 85% ethanol, are now available.

Biodiesel is made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled

cooking greases. It can be used as an additive to reduce vehicle emissions (typically 20%) or in its pure

form as a renewable alternative fuel for diesel engines.

Other biofuels include methanol and reformulated gasoline components. Methanol, commonly called

wood alcohol, is currently produced from natural gas, but could also be produced from biomass. There

are a number of ways to convert biomass to methanol, but the most likely approach is gasification.

Gasification involves vaporizing the biomass at high temperatures, then removing impurities from the

hot gas and passing it through a catalyst, which converts it into methanol.

Most reformulated gasoline components produced from biomass are pollution-reducing fuel additives,

such as methyl tertiary butyl ether (MTBE) and ethyl tertiary butyl ether (ETBE).

Biopower - Burning biomass directly, or converting it into a gaseous fuel or oil, to generate electricity.

Biopower, or biomass power, is the use of biomass to generate electricity. There are six major types of

biopower systems: direct-fired, cofiring, gasification, anaerobic digestion, pyrolysis, and small, modular.

Most of the biopower plants in the world use direct-fired systems. They burn bioenergy feed stocks

directly to produce steam. This steam is usually captured by a turbine, and a generator then converts it

into electricity. In some industries, the steam from the power plant is also used for manufacturing

processes or to heat buildings. These are known as combined heat and power facilities. For instance,

wood waste is often used to produce both electricity and steam at paper mills.

Many coal-fired power plants can use cofiring systems to significantly reduce emissions, especially sulfur

dioxide emissions. Cofiring involves using bio-energy feed stocks as a supplementary energy source in

high efficiency boilers.

Gasification systems use high temperatures and an oxygen-starved environment to convert biomass into

a gas (a mixture of hydrogen, carbon monoxide, and methane). The gas fuels what's called a gas turbine,

which is very much like a jet engine, only it turns an electric generator instead of propelling a jet.

The decay of biomass produces a gas - methane - that can be used as an energy source. In landfills, wells

can be drilled to release the methane from the decaying organic matter. Then pipes from each well carry

the gas to a central point where it is filtered and cleaned before

burning.

Methane also can be produced from biomass through a process called

anaerobic digestion. Anaerobic digestion involves using bacteria to

decompose organic matter in the absence of oxygen.

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Methane can be used as an energy source in many ways. Most facilities burn it in a boiler to produce

steam for electricity generation or for industrial processes. Two new ways include the use of micro

turbines and fuel cells. Micro turbines have outputs of 25 to 500 kilowatts. About the size of a

refrigerator, they can be used where there are space limitations for power production. Methane can

also be used as the "fuel" in a fuel cell. Fuel cells work much like batteries but never need recharging,

producing electricity as long as there's fuel. In addition to gas, liquid fuels can be produced from

biomass through a process called pyrolysis. Pyrolysis occurs when biomass is heated in the absence of

oxygen. The biomass then turns into a liquid called pyrolysis oil, which can be burned like petroleum to

generate electricity. A biopower system that uses pyrolysis oil is being commercialized.

Several biopower technologies can be used in small, modular systems. A small, modular system

generates electricity at a capacity of 5 megawatts or less. This system is designed for use at the small

town level or even at the consumer level. For example, some farmers use the waste from their livestock

to provide their farms with electricity. Not only do these systems provide renewable energy, whatever

products we can make from fossil fuels, we can make using biomass. These bioproducts, or biobased

products, are not only made from renewable sources, they also often require less energy to produce

than petroleum-based products.

Researchers have discovered that the process for making biofuels - releasing the sugars that make up

starch and cellulose in plants - also can be used to make antifreeze, plastics, glues, artificial sweeteners,

and gel for toothpaste.

Other important building blocks for bioproducts include carbon monoxide and hydrogen. When biomass

is heated with a small amount of oxygen present, these two gases are produced in abundance. Scientists

call this mixture biosynthesis gas. Biosynthesis gas can be used to make plastics and acids, which can be

used in making photographic films, textiles, and synthetic fabrics.

When biomass is heated in the absence of oxygen, it forms pyrolysis oil. A chemical called phenol can be

extracted from pyrolysis oil. Phenol is used to make wood adhesives, molded plastic, and foam

insulation.

+Small, modular systems also have potential as distributed energy resources. Distributed energy

resources refer to a variety of small, modular power-generating technologies that can be combined to

improve the operation of the electricity delivery system.

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Bioproducts - Converting biomass into chemicals for making products that typically are made from

petroleum.

Whatever products we can make from fossil fuels, we can make using biomass. These bioproducts, or

biobased products, are not only made from renewable sources, they also often require less energy to

produce than petroleum-based products.

Researchers have discovered that the process for making biofuels - releasing the sugars that make up

starch and cellulose in plants - also can be used to make antifreeze, plastics, glues, artificial sweeteners,

and gel for toothpaste.

Biomass can be used to produce a variety of biodegradable plastic products. Credit: Warren Gretz

Other important building blocks for bioproducts include carbon monoxide and hydrogen. When biomass

is heated with a small amount of oxygen present, these two gases are produced in abundance. Scientists

call this mixture biosynthesis gas. Biosynthesis gas can be used to make plastics and acids, which can be

used in making photographic films, textiles, and synthetic fabrics.

When biomass is heated in the absence of oxygen, it forms pyrolysis

oil. A chemical called phenol can be extracted from pyrolysis oil.

Phenol is used to make wood adhesives, molded plastic, and foam

insulation.

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Water power

Moving water has kinetic energy. This can be transferred into useful energy in different ways.

Hydroelectric power (HEP) schemes store water high up in dams. The water has gravitational potential

energy which is released when it falls.

Let's see a good example of how water can be used to generate electricity.

As the water rushes down through pipes, this stored energy is transferred to kinetic energy, which turns

electricity generators.

The Dam is built to retain the water. More electricity is produced if the water is more in the reservoir

Sluice Gates: These can open and close to regulate the amount of water that is released into the pipes.

Potential energy in the retained water is transferred into kinetic energy by water flowing through the

pipes with high speed.

The force and high pressure in the water turns a series of shafts in a generator. Spinning shafts in the

generator charges millions of coils and magnets to create electricity, which is regulated by a

transformer? This is then transported via cables to homes and factories.

To build a dam there has to be valleys and rivers that flow all year round. This will help with the building

and success of the dam. This way, the fullest effect of the waters kinetic energy can be tapped.

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Did you know...

Hydropower is renewable energy source that

doesn't cause global warming because it doesn't

releases dangerous greenhouse gases.

China is the largest producer of hydroelectricity,

followed by Canada, Brazil, and the United States

(Source: Energy Information Administration).

Hydropower is the most important and widely-used

renewable source of energy.

The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir.

Water released from the reservoir flows through a turbine, spinning it, which in turn activates a

generator to produce electricity. But hydroelectric power doesn't necessarily require a large dam. Some

hydroelectric power plants just use a small canal to channel the river water through a turbine.

Another type of hydroelectric power plant - called a pumped storage plant - can even store power. The

power is sent from a power grid into the electric generators. The generators then spin the turbines

backward, which causes the turbines to pump water from a river or lower reservoir to an upper

reservoir, where the power is stored. To use the power, the water is released from the upper reservoir

back down into the river or lower reservoir. This spins the turbines forward, activating the generators to

produce electricity.

A small or micro-hydroelectric power system can produce enough electricity for a home, farm, or ranch.

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Advantages and disadvantages of renewable energy:

Energy Type Advantages Disadvantages

Solar Reduces dependency on fossil fuel and coal

Renewable, endless supply that belongs to no one

Low environmental effect No Co2 emission

Can be constructed faster

Can provide electricity to poor and remote people

Low efficiency High costs Need access to sun

most of the time Energy has to be

stored in batteries, hydrogen, water or other matter

Wind Power High efficiency Very low

environmental effect No CO2 emission Quick construction Does not produce

wastes

Wind turbines are noisy

Requires steady wind Visual pollution—

Many people disapprove the idea to install because it can disrupt the landscape

High possibility of killing birds

Low energy production

Biomass Can make use of agricultural, timber, and urban wastes

Moderate costs Easy to convert to a

high energy portable fuel such as alcohol or gas

Very low in sulphur reducing the production of acid

Moderate to high environmental effect

Soil erosion, water pollution, and loss of wildlife habitat

More expensive than conventional fossil fuel

A less concentrated form of energy, making it less

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rain efficient