Book excerpt: Renewable Power Pathways is the result of a study by the National Research Council (NRC) Committee for the Programmatic Review of the Office of Power Technologies (OPT) review of the U.S. Department of Energy's (DOE) Office of Power Technologies and its research and development (R&D) programs. The OPT, which is part of the Office of Energy Efficiency and Renewable Energy, conducts R&D programs for the production of electricity from renewable energy sources. Some of these programs are focused on photovoltaic, wind, solar, thermal, geothermal, biopower, and hydroelectric energy technologies; others are focused on energy storage, electric transmission (including superconductivity), and hydrogen technologies. A recent modest initiative is focused on distributed power-generation technologies. This report reviews the activities of each of OPT's programs and makes recommendations for OPT as a whole and major recommendations for individual OPT programs.