An Overview of How Electricity Is Produced
A traditional electric power plant generates electricity by burning a fossil fuel such as coal or natural gas. The heat generated by this combustion is used to boil water, producing steam. The steam causes a turbine of coiled wire to turn in a magnetic field (or vice versa -- it causes a magnet to turn in a coil of wire). When a coil of wire is rotated in a magnetic field, electrons begin to flow in the wires. A flow of electrons in a wire equals electricity!
This animation was created by Jill Mack.
Some forms of alternative energy generate electricity in the same fashion. The major difference is that instead of using combustion of fossil fuels to turn the turbine, other energy sources are utilized. For example, wind power utilizes windmills that turn the turbines of coiled wire to produce electricity. Nuclear energy relies on the heat generated by the splitting of uranium atoms to convert liquid water to steam, which in turn rotates a turbine of coiled wire. Sometimes wood or cornstalks or garbage or other organic matter (collectively referred to as biomass) is burned and causes the water to boil. Rays of sunlight, focused with mirrors, can even generate enough heat to boil the water. (An example of this type of power plant can be seen in the Mohave desert.) Water flowing over dams can also turn turbines; this is referred to as "hydroelectric power." The ebb and flow of the tides, caused by the gravitational pull of the sun and moon on the Earth's oceans, are utilized to turn a turbine in a few tidal power plants, most notably at the 240-megawatt plant that operates in La Rance, France. A few geothermal plants, which use the heat from inside the earth to turn a turbine, exist around the globe. For example, 21 such plants operate in The Geysers region in northwestern California.
Other types of alternative energy produce electricity in a more direct fashion. Fuel cells, for instance, extract electrons from H2 gas to produce an electric current, and photovoltaic cells rely on photons of light from the sun to set electrons in a semiconductor in motion, thus producing an electric current.
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