Wind and solar power constitute 3.6 percent of the U.S. electricity supply. Both fuels enjoy enormous political support. If they could be developed in an economically competitive form, these fuels would provide dream solutions to two intractable policy problems: reducing greenhouse gas emissions and providing the country with a renewable energy source, independent of foreign suppliers. However, the costs of wind and solar power currently far exceed those of conventional fuels, such as natural gas. They are viable energy choices only when heavily subsidized by governments, due to problems presented by their physical characteristics that engineers have been unable to transcend.
Wind and solar share three characteristics that make them relatively unattractive fuel choices if judged by cost alone: