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Coal-fired Power Plant.  Photo by Warren Gretz.


Electricity from:
Coal



Coal is the solid end-product of millions of years of decomposition of organic materials. In truth, coal is stored solar energy. Plants capture the energy from sunlight through photosynthesis, which directly converts solar energy to plant matter. Animals that then eat the plants to convert that energy again, storing it in their own bodies.

Over millions of years, accumulated plant and animal matter is covered by sediment and stored within the earth's crust, gradually being transformed into hard black solids by the sheer weight of the earth's surface. Coal, like other fossil fuel supplies, takes millions of years to create, but releases its stored energy within only a few moments when burned to generate electricity. Because coal is a finite resource, and cannot be replenished once it is extracted and burned, it cannot be considered a renewable resource.

The nation's fleet of over 100 coal plants is responsible for 57 percent of the electricity generated in the U.S., more than any other single electricity fuel source.

Coal is typically burned to create steam, which is then piped at high pressure over a turbine, causing it to rotate, producing electricity. This steam electric system is a common one also used with other fuel sources, including oil, natural gas, geothermal, biomass, and even some solar-fueled systems.


What are the environmental issues?

The popularity of coal is largely due to its low cost.

Nevertheless, coal power plants are responsible for 93 percent of the sulfur dioxide and 80 percent of the nitrogen oxide emissions generated by the electric utility industry.

These emissions spawn the acid rain that is eating away red spruce forests in the Northeast and Appalachia, and rob previously pristine streams of brook trout and other fish species in the Adirondacks, upper Midwest and Rocky Mountains.

Coal emissions also cause urban smog, which has been linked to respiratory ailments, and coal-fired power plants also contribute to global climate change. Coal plants emit 73 percent of the carbon dioxide emitted into the atmosphere from electricity generators. By releasing the energy stored in coal, large quantities of carbon dioxide that have been stored in the coal for millions of years are released back into the atmosphere, increasing the threat of global warming. Coal plants are also a major source of airborne emissions of mercury, a toxic heavy metal.

Federal law requires that air pollution be kept within limits. However, these limits are significantly lower for older coal plants than for newer ones. Even when kept within the air emission limits set by the Clean Air Act, state-of-the-art coal power plants still produce significant damage to human health, public and private property, and ecosystems.

The mining, processing, and transporting of coal also insults the environment. In the West, about 87 percent of coal is removed from the earth through strip mining, which can contaminate soils with heavy metals and destroy near-surface aquifers. In the East, coal is sometimes mined by removing entire mountain tops to more easily extract the subsurface mineral reserves.

Coal combustion also results in huge quantities of solid wastes. Enormous quantities of waste heat require large amounts of water for cooling. The collection of this water from major water bodies threatens local aquatic life, including the killing of fish on the screens designed to keep such organisms out of the power plant.


Additional Information:
U.S. Dept. of Energy's Energy Information Administration (EIA): "Coal Information at a Glance" http://www.eia.doe.gov/fuelcoal.html

Union of Concerned Scientists - USA: Coal
http://ucsusa.org/clean_energy/renewable_energy/page.cfm?pageID=60


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