RENEWABLE ENERGY SOURCES
RENEWABLE ENERGY SOURCES
Includes
 Biomass
 Hydropower
 Geothermal
 Wind
 Solar
Provides 7% of the energy used in the U.S.
 Most of that energy goes to producing
electricity.

RENEWABLE RESOURCE USE IN THE U.S.
About 9% of U.S. electricity was generated from
renewable sources in 2008.
 The next largest use of renewable energy is the
production of heat and steam for industrial
purposes.
 Renewable fuels, such as ethanol, are also
used for transportation and to provide heat for
homes and businesses.

THE ROLE OF RENEWABLE ENERGY IN
THE U.S.
Renewable energy plays an important role in
the supply of energy.
 When renewable energy sources are used, the
demand for fossil fuels is reduced.
 Renewable energy has generally been more
expensive to produce and use than fossil fuels.

Renewable resources are often located in
remote areas, and it is expensive to build power
lines to the cities where the electricity they
produce is needed.
 The use of renewable sources is also limited by
the fact that they are not always available —
cloudy days reduce solar power; calm days
reduce wind power; and droughts reduce the
water available for hydropower

The production and use of renewable fuels has
grown more quickly in recent years as a result of
higher prices for oil and natural gas, and a number
of State and Federal Government incentives,
including the Energy Policy Acts of 2002 and
2005.
 The use of renewable fuels is expected to continue
to grow over the next 30 years, although we will
still rely on non-renewable fuels to meet most of
our energy needs.

BIOMASS
Biomass is organic material made from plants
and animals.
 Biomass contains stored energy from the sun.
 When burned, the chemical energy in biomass
is released as heat.
 The wood you burn is a biomass fuel. Wood
waste or garbage can be burned to produce
steam for making electricity, or to provide heat
to industries and homes.

CONVERTING BIOMASS TO OTHER FORMS OF
ENERGY
Burning biomass is not the only way to release its
energy.
 Biomass can be converted to other useable forms
of energy, such as methane gas or transportation
fuels, such as ethanol and biodiesel.
 Methane gas is the main ingredient of natural gas.
Smelly stuff, like rotting garbage, and agricultural
and human waste, release methane gas — also
called "landfill gas" or "biogas."

•Crops
like corn and sugar
cane can be fermented to
produce ethanol.
•Biodiesel, another
transportation fuel, can be
produced from left-over
food products like vegetable
oils and animal fats.
•Biomass fuels provide
about 4% of the energy
used in the United States
WOOD AS A BIOFUEL
The most common form of biomass is wood. For
thousands of years people have burned wood for
heating and cooking.
 Wood was the main source of energy in the United
States and the rest of the world until the mid1800s.
 Wood continues to be a major source of energy in
much of the developing world.
 In the United States, wood and wood waste (bark,
sawdust, wood chips, and wood scrap) provide
about 2% of the energy we use today.

BIOFUELS
"Biofuels" are transportation fuels like ethanol and
biodiesel that are made from biomass materials.
 These fuels are usually blended with the
petroleum fuels — gasoline and diesel fuel, but
they can also be used on their own.
 Using ethanol or biodiesel means we don't burn
quite as much fossil fuel.
 Ethanol and biodiesel are usually more expensive
than the fossil fuels that they replace, but they are
also cleaner-burning fuels, producing fewer air
pollutants

BIODIESEL
Biodiesel is a fuel made from vegetable oils, fats,
or greases — such as recycled restaurant grease.
 Biodiesel fuel can be used in diesel engines
without changing them.
 It is the fastest growing alternative fuel in the
United States.
 Biodiesel, a renewable fuel, is safe,
biodegradable, and produces lower levels of most
air pollutants than petroleum-based products.

ETHANOL MADE FROM CORN AND OTHER
CROPS
Ethanol is a clear, colorless alcohol fuel made
from the sugars found in grains, such as corn,
sorghum, and barley, as well as potato skins,
rice, sugar cane, sugar beets, and yard
clippings.
 Ethanol is a renewable fuel because it is made
from plants. There are several ways to make
ethanol from these sources.

The most common processes today use yeast
to ferment the sugars and starch in corn.
 Corn is the main ingredient for ethanol in the
United States due to its abundance and low
price.
 Most ethanol is produced in the corn-growing
States in the Midwest. The starch in the corn is
fermented into sugar, which is then fermented
into alcohol.

Sugar cane and sugar beets are the most common
ingredients used to make ethanol in other parts of
the world.
 Since alcohol is created by fermenting sugar,
sugar crops are the easiest ingredients to convert
into alcohol.
 Brazil, the country with the world's largest ethanol
production, makes most of its ethanol from sugar
cane. Today, many cars in Brazil run on ethanol.

Ethanol can also be produced by breaking down
cellulose in woody fibers.
 Cellulosic ethanol is considered an “advanced”
biofuel and involves a more complicated
production process than conventional ethanol
made from starches or sugars.
 However, with this process we can make ethanol
from trees, grasses, and crop wastes, reducing
concerns that increasing ethanol production will
reduce food supply.

In 2005, a renewable fuel standard was
enacted that set minimum requirements for the
use of renewable fuels, including ethanol.
 In 2007, the RFS targets were substantially
raised and now rise steadily to a level of 36
billion gallons by 2022.

GEOTHERMAL ENERGY
Geothermal energy is generated in the Earth's
core. Temperatures hotter than the sun's surface
are continuously produced inside the Earth by the
slow decay of radioactive particles, a process that
happens in all rocks.
 Heat from the mantle reaches the surface in
places where continental plates come together
and hotspots like the geysers at Yellowstone
National park and the Hawaiian Islands. These are
called geothermal reservoirs.

Most geothermal reservoirs are deep
underground with no visible clues showing
above ground.
 When magma comes close to the surface, it
heats ground water found trapped in porous
rock or water running along fractured rock
surfaces and faults. These features are called
hydrothermal vents


Geologists use various methods to look for
geothermal reservoirs. Drilling a well and
testing the temperature deep underground is
the most reliable method for finding a
geothermal reservoir.
:

People around the world use geothermal
energy to heat their homes and to produce
electricity by digging deep wells and pumping
the heated underground water or steam to the
surface. We can also make use of the stable
temperatures near the surface of the Earth to
heat and cool buildings.
USE OF GEOTHERMAL ENERGY

Some applications of geothermal energy use
the Earth's temperatures near the surface,
while others require drilling miles into the
Earth. The three main uses of geothermal
energy are: .
Direct use and district heating systems use hot
water from springs or reservoirs near the surface
 Electricity generation power plants require water or
steam at very high temperature (300° to 700°F).
Geothermal power plants are generally built where
geothermal reservoirs are located within a mile or
two of the surface.
 Geothermal heat pumps use stable ground or
water temperatures near the Earth's surface to
control building temperatures above ground.

DIRECT USE OF GEOTHERMAL ENERGY
the most common direct use of geothermal energy
is for heating buildings through district heating
systems. Hot water near the Earth's surface can
be piped directly into buildings and industries for
heat. A district heating system provides heat for
95% of the buildings in Reykjavik, Iceland.
 Industrial applications of geothermal energy
include food dehydration, gold mining, and milk
pasteurizing. Dehydration, or the drying of
vegetable and fruit products, is the most common
industrial use of geothermal energy.

GEOTHERMAL IN THE US
The United States generates more geothermal
electricity than any other country, but the amount
of electricity it produces is less than 0.5% of all
electricity produced in United States. Only four
States have geothermal power plants:
 California has 34 geothermal power plants, which
produce almost 90% of U.S. geothermal electricity.
 Nevada has 15 geothermal power plants.
 Hawaii, Montana, and Utah each have one
geothermal plant.

TYPES OF GEOTHERMAL PLANTS




There are three basic types of geothermal power plants:
Dry steam plants use steam piped directly from a
geothermal reservoir to turn the generator turbines. The
first geothermal power plant was built in 1904 in
Tuscany, Italy, where natural steam erupted from the
Earth.
Flash steam plants take high-pressure hot water from
deep inside the Earth and convert it to steam to drive
the generator turbines. When the steam cools, it
condenses to water and is injected back into the ground
to be used over and over again. Most geothermal power
plants are flash steam plants.
Binary cycle power plants transfer the heat from
geothermal hot water to another liquid. The heat causes
the second liquid to turn to steam which is used to drive
a generator turbine.
•GEOTHERMAL ENERGY & THE ENVIRONMENT

The environmental impact of geothermal energy depends on
how it is being used. Direct use and heating applications
have almost no negative impact on the environment.

Geothermal power plants do not burn fuel to generate
electricity, so their emission levels are very low. They release
less than 1% of the carbon dioxide emissions of a fossil fuel
plant.

Geothermal plants use scrubber systems to clean the air of
hydrogen sulfide that is naturally found in the steam and hot
water.
GEOTHERMAL POWER PLANT

Geothermal plants emit 97% less acid rain-causing sulfur
compounds than are emitted by fossil fuel plants. After the
steam and water from a geothermal reservoir have been used,
they are injected back into the Earth.
HYDROPOWER BASICS
ENERGY FROM MOVING WATER

Hydropower is the renewable energy source
that produces the most electricity in the United
States. It accounted for 6% of total U.S.
electricity generation and 67% of generation
from renewables in 2008.
MECHANICAL ENERGY IS HARNESSED FROM
MOVING WATER

The amount of available energy in moving water
is determined by its flow or fall. Swiftly flowing
water in a big river, like the Columbia River that
forms the border between Oregon and
Washington, carries a great deal of energy in its
flow. Water descending rapidly from a very high
point, like Niagara Falls in New York, also has
lots of energy in its flow.
In either instance, the water flows through a
pipe, or penstock, then pushes against and
turns blades in a turbine to spin a generator to
produce electricity.
 In a run-of-the-river system, the force of the
current applies the needed pressure,
 In a storage system, water is accumulated in
reservoirs created by dams, then released as
needed to generate electricity.

WHERE HYDROPOWER IS GENERATED

Over half of U.S. hydroelectric capacity for
electricity generation is concentrated in three
States: Washington, California, and Oregon.
Approximately 31% of the total U.S. hydropower
is generated in Washington, the location of the
Nation's largest hydroelectric facility — the
Grand Coulee Dam.
HYDROPOWER & THE ENVIRONMENT


Hydropower does not pollute the water or the air.
However, hydropower facilities can have large
environmental impacts by changing the environment
and affecting land use, homes, and natural habitats in
the dam area.
Most hydroelectric power plants have a dam and a
reservoir. These structures may obstruct fish migration
and affect their populations. Operating a hydroelectric
power plant may also change the water temperature and
the river's flow. These changes may harm native plants
and animals in the river and on land.

Reservoirs may cover people's homes,
important natural areas, agricultural land, and
archeological sites. So building dams can
require relocating people. Methane, a strong
greenhouse gas, may also form in some
reservoirs and be emitted to the atmosphere.

In the Columbia River, along the border of Oregon and
Washington, salmon must swim upstream to their spawning
grounds to reproduce, but the series of dams gets in their way.
Different approaches to fixing this problem have been used,
including the construction of "fish ladders" which help the
salmon "step up" the dam to the spawning grounds upstream.
TIDAL POWER
Tides are caused by the gravitational pull of the
moon and sun, and the rotation of the Earth.
Near shore, water levels can vary up to 40 feet
due to tides.
 Tidal power is more predictable than wind
energy and solar power. A large enough tidal
range — 10 feet — is needed to produce tidal
energy economically.

TIDAL BARRAGES
A simple generation system for tidal plants
involves a dam, known as a barrage, across an
inlet.
 Sluice gates (gates commonly used to control
water levels and flow rates) on the barrage allow
the tidal basin to fill on the incoming high tides
and to empty through the turbine system on the
outgoing tide, also known as the ebb tide.
 There are two-way systems that generate
electricity on both the incoming and outgoing
tides.


A potential disadvantage of tidal power is the
effect a tidal station can have on plants and
animals in the estuaries. Tidal barrages can
change the tidal level in the basin and increase
turbidity (the amount of matter in suspension
in the water). They can also affect navigation
and recreation.
WAVE POWER

Waves are caused by the wind blowing over the
surface of the ocean. There is tremendous
energy in the ocean waves. It's estimated that
the total potential off the coast of the United
States is 252 billion kilowatthours a year, about
7% of the United States' electricity consumption
in 2008. The west coasts of the United States
and Europe and the coasts of Japan and New
Zealand are good sites for harnessing wave
energy.

One way to harness wave energy is to bend or focus
the waves into a narrow channel, increasing their
power and size. The waves can then be channeled into
a catch basin or used directly to spin turbines.

Many more ways to capture wave energy are currently under
development. Some of these devices being developed are
placed underwater, anchored to the ocean floor, while others
ride on top of the waves. The world's first commercial wave
farm using one such technology opened in 2008 at the
Aguçadora Wave Park in Portugal.