Original: The first power plants were run on water power or coal,Pearl Street Station: The Dawn of Commercial Electric Power and today we rely mainly on coal, nuclear, natural gas, hydroelectric, and petroleum with a small amount from solar energy, tidal harnesses, wind generators, and geothermal sources.
Simplified: Power plants are run on coal, nuclear, natural gas, hydroelectric, and petroleum power and a small amount from solar energy, tidal harnesses, wind generators, and geothermal sources.