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 .