Sources of Energy and Electricity

Sources of Energy and Electricity

Most of a typical U.S. consumer's energy comes from the burning of fossil fuels. Fossil fuels include coal, oil, and natural gas. Fossil fuels cause air pollution when they are burned and also cause indirect environmental effects. These indirect environmental effects include the extraction of fuel from the earth, the construction and maintenance of transportation facilities and pipelines to deliver the fuel to where it is used, and the construction of electric generating plants and electric transmission and distribution lines. Fossil fuels are not renewable - we are currently using them faster than they can be replenished.

Nuclear energy currently provides about 20% of the electricity generated in the United States. Nuclear power is created by the splitting (fission) of atomic nuclei, namely uranium or plutonium. This process generates the necessary heat to convert water to steam to drive turbines that generate electricity. Although nuclear power emits little air pollution, the storage of radioactive nuclear waste and chances of nuclear reactor accidents are environmentally dangerous and controversial.

In contrast to fossil fuels, renewable energy is often in infinite supply and less polluting. Renewable energy includes solar (photovoltaics), wind, biomass, hydropower, and geothermal. Renewable energy can be used as a form of supplying energy in homes and businesses, and can also be converted directly to electricity.

Currently, most electricity production in the United States currently comes from coal-fired power plants. In some areas, consumers can impact the amount of air pollution emitted from power plants by choosing to buy electricity generated by renewables or cleaner fossil fuels. Green electric power is being offered in parts of the country where electric utility deregulation has occurred, such as California, Pennsylvania, and Massachusetts. Where electric industry competition does not exist, some utilities offer special "green rates" to their customers for electricity generated from renewables. In this case, these rates are set by regulations rather than competition. Consumers also need to make sure any premiums they pay for green electricity are going towards new, not mandated, renewable generation.

Renewables

Energy from the sun can be used in several ways. For example, solar energy can be used to heat homes by taking advantage of south-facing windows (solar heating), and can be used to heat water (solar water heating) with flat plate solar collectors. Energy from the sun can also be used to generate electricity. Sunlight can be used to heat water to create steam, which powers a turbine and generates electricity (solar thermal electric power). Photovoltaic (PV) cells, or solar cells (much like those on a solar calculator), convert sunlight directly into electricity. Thousands and thousands of these cells can be joined together to form a photovoltaic system that can be incorporated into an electric utility's supply network.

Photovoltaic systems are ideal for remote or rural villages, and stand alone sites or residences. In early July 1998, photovoltaics became the fastest-growing energy source, as world-wide production increased 40% in the past year. Converting solar energy into electricity suffers from the constraint that electricity cannot be produced when the sun isn't shining, like on cloudy days or at night. Photovoltaic energy systems can also be relatively expensive, however, it is expected that prices will continue to drop until photovoltaic is an economical energy source.

Wind can also be used to generate electricity and is the second-fastest growing energy source. Blades on a wind turbine turn when the wind blows, and drive a generator which produces electricity. Large groups of wind turbines are called wind farms. Wind energy can be used for individual residences and businesses, or can be connected to a utility power grid and transmitted over power lines. In order to generate electricity, wind speeds must be sustained above about 10 mph, although average wind speeds of at least 14 mph are desirable. Since wind speeds are less at ground level than at higher elevations, more wind power can be achieved with taller towers. Wind turbines are usually constructed in the windiest areas, although there are many locations throughout the United States and the rest of the world that are suitable for wind power production. Wind energy is an intermittent source since wind does not blow at consistent speeds and times. For this reason, small wind systems may need to use batteries for backup.

Biomass serves as another renewable energy source. Wood is the most common biomass fuel, but biomass includes many types of organic matter that can be converted into energy, such as plants, agricultural products and by-products (such as corn and sugarcane residue), animal waste, and even garbage. Biomass fuels can be burned to generate heat and electricity directly, converted to gaseous fuel like methane, or converted to liquid fuel such as ethanol and methanol. Agreement has not yet been reached regarding which types of biomass energy should be regarded as renewable or green energy.

Geothermal energy comes directly from the interior of the earth. The heat from hot, molten rock far below the earth's surface can be used heat large reservoirs of water, or to create steam that can be used to power turbines that generate electricity.

Hydropower accounts for over 90% of all electricity that comes from renewable resources. Electricity can be generated by collecting water in a reservoir, such as behind a dam, and then allowing it to flow past a turbine that is connected to a generator. By comparison, water is cleaner than fossil fuels for electricity generation, however, large dams stop the natural flow of water which can destroy vegetation, aquatic life, and cause other serious ecological damage.

Much more detailed information on renewable energy resources is widely available on the Web. The Energy Efficiency and Renewable Energy Network of the U.S. Department of Energy is one such source (www.eere.energy.gov)

Energy produced from renewable sources offers many environmental benefits over fossil fuels. When we buy electricity produced by renewable energy, like wind for example, we reduce the emission of air pollutants associated with the burning of fossil fuels. We also reduce the need for fuel extraction from the earth, fuel transportation systems, pipelines, and other infrastructure. However, power plants in the form of wind generators and electric transmission and distribution lines must still be built to deliver power to customers.

Electricity generated by renewables also has positive emission reduction benefits, but availability can be restricted by the status of electric industry deregulation. In areas where utilities still have a retail monopoly, green electricity is only available to consumers if the utility chooses to make it available, or if regulations require that it be made available. Furthermore, where utilities still have retail monopolies, any green electricity services are only available at non-competitive prices set through the regulatory process. Where utility deregulation has created fully competitive retail energy services markets, green electricity can be purchased at prices set by the competitive market, i.e. at lower prices than where the utility still has a retail monopoly. However, in many emerging competitive markets, transition costs will delay this effect for several years.

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