ABSTRACT
Renewable energy sources in the United States include solar heat and electricity and indirect solar sources like wind, falling water, biomass, wave, ocean current, and ocean temperature differences, as well as geothermal and tidal possibilities. The first two sources, solar radiation and wind, are very large. Solar radiation exceeds total U.S. energy use by a factor of 440, while the wind energy potential is three times the annual electricity use. Hydroelectric, biomass, and geothermal sources are commercially developed, as well, and can supply half the nation’s energy. The largest sources are also intermittent in nature, thus raising issues of complementarity and storage in high-renewable energy scenarios. U.S. energy use, now in the 100-quad range, can be greatly reduced by efficiency gains. Energy end-uses in the forms of heat, liquid fuels, and electricity are examined. Reduced energy demands can be met largely or wholly via renewable sources, thus preserving relatively high living standards in a sustainable manner, given time, commitment, and further development of two or three key technologies.
