Energy
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Where Does Electricity Come From?

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Power plants make electricity out of other forms of energy. Most electricity in the U.S. today comes from converting the heat energy released from burning fossil fuels--coal, natural gas and oil. The rest is generated from nuclear reactors and from renewable sources, such as sunlight, wind, falling water and geothermal heat (see Renewables, Unit 5).

In a typical power plant, a primary energy source like coal is burned to create heat, which is converted in a boiler to mechanical energy in the form of superheated, high-pressure steam. The steam is directed into a turbine, where it pushes on blades attached to a central shaft or rotor. The rapidly spinning rotor powers a generator.

Figure 2. Energy pathway. Most power plants produce electricity by converting the energy in fossil fuels to steam. 

Figure 2
Energy pathway
Most power plants produce electricity by converting the energy in fossil fuels to steam.

Click on image to see animation.