Cn604 topic 2 renewable energy

Topic 2: Renewable Energy
CN604: Energy System Page 1
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

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.

• 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

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%.

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.

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.

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.

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...Did you know...Did you know...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.

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.

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.

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

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.

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.

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.

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
2.2.2.2. This is burned to heat water in a boiler
to release heat energy (steam).
3.3.3.3. The energy/power from the steam is
directed to turbines with pipes
4.4.4.4. The steam turns a number of blades in
the turbine and generators, which are
made of coils and magnets.
5.5.5.5. The charged magnetic feilds produce
electricity, which is sent to homes by
cables

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.

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.

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.

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.

Did you know...Did you know...Did you know...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.

Cn604 topic 2 renewable energy

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