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 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.
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.
|