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 mid-1800s.

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 BASICSENERGY 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.