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Turning the Light on Electricity

2:33 PM June 24, 2009

In October 1879, Thomas Edison unveiled the first commercially practical electric light bulb. Three years later, Edison's first power plant lit up New York City.

Today the industry that once brought "smokeless light" to American cities supplies power for homes, businesses, industries, and transportation, not to mention more than 176 million personal computers and a national network of more than 200 million cellular phones. America's demand for electricity is growing and is expected to increase at least 26 percent by 2030.

Electricity, one of our most widely used forms of energy, is a secondary energy source which we get by converting other sources of energy. These sources can be renewable - that is, virtually inexhaustible in duration and constantly replenished, but limited in the amount of energy that's available at a particular time. Hydro (water), wind, solar, geothermal, and biomass, for example, are renewable. Other sources may be nonrenewable - not replenished by nature - such as oil, coal, natural gas, and uranium for nuclear energy.

Generating electricity - that is, turning energy into electricity - is accomplished through several different methods including: 

§  Burning fossil fuels such as oil, coal, or natural gas

§  Using a nuclear reactor to produce boiling water that turns turbines producing electricity

§  Capturing kinetic energy from hydro or wind, and using solar and photovoltaic devices, called solar electric cells, that change sunlight directly into electricity.

Most of the electricity generated in the United States comes from burning coal. In fact, nearly half (49 percent) of the country's electricity uses coal as its energy source.

Electricity is usually delivered by a local utility company through the network of existing transmission and distribution lines often referred to as the "grid."


The Impact of Electricity on Global Warming and Health

The origin of the electricity we use is important because electricity generation is the dominant source of carbon dioxide (CO2) emissions in the U.S. today. In fact, the average American home's electricity usage results in 18,000 pounds of CO2 a year released into the atmosphere. Some sources of electricity produce emissions that damage the environment and endanger human health, while others do not.

The burning, or combustion, of fossil fuels such as coal, oil, and natural gas to generate electricity produces airborne gases and particulates that are released into the atmosphere. Some of these gases, such as CO2, are called greenhouse gases (GHGs); other GHGs include sulfur dioxide and nitrogen oxides. CO2 is the most prevalent GHG, and fossil-fuel burning electric power plants, especially coal, are its primary source. Coal-fired power plants are among the largest contributors of pollution from particulate matter, ozone and toxics, including mercury, lead, and arsenic. However, several new pollution-control technologies designed to reduce emissions of coal-related pollutants are in development.

According to the U.S. Environmental Protection Agency (EPA), GHGs are now at record-high levels in the atmosphere compared to the recent and distant past, and they threaten public health and welfare. These gases collect in the atmosphere, trap the sun's heat and cause the planet to warm up in the process we know as global warming.

The EPA warns that global warming is expected to cause more frequent and intense heat waves; wildfires; degraded air quality; heavier downpours and flooding; increased drought; greater sea level rise; more intense storms; and harm to water resources, agriculture, wildlife, and ecosystems.

Additionally, harmful health effects are associated with elevated greenhouse gas concentrations in the U.S.  Global warming is expected to worsen regional ozone pollution, with associated risks in respiratory infection, aggravation of asthma, and premature death. Certain climate-sensitive diseases are also expected to increase.

To reduce GHGs and other dangerous forms of air pollution, many experts believe we must decrease our dependence on fossil fuels and rely instead on energy sources that do not produce harmful airborne emissions.


Emission-free Energy Sources

Renewable energy sources such as hydroelectric, wind, solar, and geothermal produce virtually no emissions.  Nuclear energy also produces no GHGs in the production of electricity because nothing is burned.  

Among renewable energy sources that generate electricity, hydropower accounted for 6 percent of the nation's electric power in 2008. Other non-hydro renewables (biomass, geothermal, solar, and wind) accounted for approximately 3 percent of total electricity generated. Nuclear energy generated 20 percent of our nation's electricity. Of these emission-free sources, currently only hydropower and nuclear operate around the clock - 24/7 - to generate dependable power to consistently meet demand.



Nuclear plants, like plants that burn coal, oil, and natural gas, produce electricity by boiling water into steam. This steam then turns turbines to produce electricity. The difference is that nuclear plants do not burn anything.  Instead, they use uranium fuel in the shape of ceramic pellets to produce electricity through a process called fission.

Nuclear energy generates electricity from 104 reactors for one in five homes and businesses in the U.S. without emitting air pollution or contributing to global warming. In 2007, U.S. nuclear power plants avoided the emission of 1 million short tons of nitrogen oxides--the same amount emitted by more than 51 million passenger cars in a year. Generating nuclear power does, however, produce spent fuel that is stored safely onsite at nuclear plants or at designated facilities.



Hydroelectric power uses the kinetic energy of moving water to make electricity. 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 and streams, its energy can be captured using hydropower.

There are several types of hydropower facilities; some use dams and some do not. They range in size from small systems for a home or village to large projects producing electricity for utilities. Turbines and generators convert the energy into electricity, which is then fed into the electrical grid to be used in homes, businesses, and by industry.

Over one-half of the total U.S. hydroelectric capacity for electricity generation is concentrated in three states (Washington, California and Oregon), and Washington is the location of the nation's largest hydroelectric facility - the Grand Coulee Dam.

Conventional hydroelectric power is unlikely to enjoy rapid growth under current expectations, due to the lack of many additional large sites for hydroelectric facilities.



Wind power produces virtually no emissions. Wind energy is really a converted form of solar energy, created when the sun heats the earth's surface and the heat drives the winds. The wind produces energy that is captured by wind turbines. As long as the sun shines, the wind will blow.

Air in motion has kinetic energy. A wind energy system transforms the wind's kinetic energy into electrical energy that can be used. A wind turbine can harness the wind's energy; a generator then converts the mechanical energy into electrical energy for distribution and practical use. Wind electric turbines generate electricity for homes and businesses and for sale to utilities.

The most economical application of wind electric turbines is in groups of large machines called "wind power plants" or "wind farms."

Wind machines generated electricity in 28 states in 2008; the top five states with the most wind-power production are Texas, Iowa, California, Minnesota, and Washington. According to the American Wind Energy Association, wind energy could supply about 20 percent of the nation's electricity. 



Solar energy comes from the sun's rays - solar radiation - that reach the earth. Solar energy is convertible into other energy forms, such as electricity and thermal (heat) energy. Solar power converts the sun's energy into a pollution-free source of heat, lighting, and electricity.

Solar energy can be converted to electricity in two ways: Photovoltaic (PV) devices or "solar cells" change sunlight directly into electric power. PV systems are used to power watches, calculators, ATM machines, and lighted road signs. Solar thermal energy is often used to heat swimming pools, heating water used in homes, and space heating of buildings.

Around the U.S., available sunlight varies considerably as a result of differences in cloud cover and latitude, and also varies with the seasons. These variations must be taken into consideration when planning solar collection facilities. Solar power currently provides less than 1 percent of U.S. energy needs, but this percentage is expected to increase with the development of new and more efficient solar technologies.



Not all emission-free energy sources come from the sun. Geothermal energy taps the Earth's internal heat for many uses, including electric power production and the heating and cooling of buildings. Geothermal power plants use hydrothermal resources, which have two common ingredients: water (hydro) and heat (thermal). The Earth's heat can be drawn from several sources: hot water or steam reservoirs accessed by deep drilling, geothermal reservoirs located near the earth's surface (mostly located in western states, Alaska, and Hawaii), and the shallow ground near the Earth's surface that maintains a relatively constant temperature of 50°-60° F.

The U.S. generates more geothermal electricity than any other country, but the amount of electricity it produces is less than one-half of a percent of electricity produced in the U.S. States such as California, Nevada, Hawaii, and Utah have geothermal power plants, and other plants are in various stages of development in several other states. 



Sunlight causes plants to grow. Biomass uses organic matter - wood or plants - called biomass to generate heat and electricity and produce transportation fuel. Biomass energy, or "bioenergy," recycles organic leftovers from forestry and agriculture - corn stalks and leaves, rice husks, wood waste, willow, pressed sugar cane, switchgrass - as fuel to produce electricity and heat. It can be fermented to produce fuels - ethanol, for example - for cars and trucks, it can create methane gas to power turbines, and it can be heated or "gasified" to break down into a clean-burning gas to make a range of products from diesel to gasoline to chemicals. Biomass helps reduce toxic air-borne pollutants and decrease our dependency on foreign oil.

According to the American Lung Association's report, Agenda for Clean Air: Protect the Air We Breathe, clean air remains one of the nation's major environmental and public-health challenges. "Climate, energy, and clean air are inexorably linked. Solutions that lead to cleaner air must be included in any approach to cleaner, more efficient energy use and reductions in global warming," the report states.




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