This report, published by the Intergovernmental Panel on Climate Change, examines the role of renewable energy sources and technologies in the mitigation of climate change and provides policy relevant information. The authors evaluate the scientific literature on six renewable energy sources — bioenergy, direct solar energy, geothermal energy, hydropower, ocean energy and wind energy — and their current deployment. The report describes how each of these power sources can be integrated into future energy systems, and outlines future research needs in the context of sustainable development. It puts forward strategies to overcome environmental and social consequences associated with the deployment of such technologies, and compares the cost of energy from renewable sources to non-renewable sources.