05/2011_English_Jacobson/Delucchi Scientific American
Renewable energy comes from enticing sources: wind, which also produces waves; water, which includes hydroelectric, tidal and geothermal ener- gy (water heated by hot underground rock); and sun, which includes photovoltaics and solar pow- er plants that focus sunlight to heat a fluid that drives a turbine to generate electricity. Our plan includes only technologies that work or are close to working today on a large scale, rather than those that may exist 20 or 30 years from now.