If renewable power systems deliver such impressive benefits, why do they still provide only 3 percent of national electricity generation in the United States? As an answer, this article demonstrates that the impediments to renewable power are socio-technical, a term that encompasses the technological, social, political, regulatory, and cultural aspects of electricity supply and use. Extensive interviews of public utility commissioners, utility managers, system operators, manufacturers, researchers, business owners, and ordinary consumers reveal that it is these socio-technical barriers that often explain why wind, solar, biomass, geothermal, and hydroelectric power sources are not embraced. Utility operators reject renewable resources because they are trained to think only in terms of big, conventional power plants. Consumers practically ignore renewable power systems because they are not given accurate price signals about electricity consumption. Intentional market distortions (such as subsidies), and unintentional market distortions (such as split incentives) prevent consumers from becoming fully invested in their electricity choices. As a result, newer and cleaner technologies that may offer social and environmental benefits but are not consistent with the dominant paradigm of the electricity industry continue to face comparative rejection. (C) 2009 Elsevier Ltd. All rights reserved.