This report identifies renewable energy options that are currently in wide use in some regions and that are now ready for large-scale introduction in many areas of the developing world. Through 26 case studies, the report cites biogas, small hydro, solar, wind, ethanol, and biodiesel, among other technologies, as viable options for poverty alleviation in developing countries. As their cost has declined and their reliability has improved, renewable energy technologies have often emerged as more affordable and practical means of providing essential energy services. Although the strongest renewable energy growth has been in grid-connected power systems and liquid fuels for transportation, several technologies are well-suited to providing modern energy services for low-income people. Scaling up a broad portfolio of renewable energy options can make a major contribution to achieving the Millennium Development Goals, concludes the report. The creation of REN 21 was sponsored by the German Federal Ministry for Economic Cooperation and Development and the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. Formally established in Copenhagen in June 2005, REN 21 is now supported by a steering committee of 11 governments, five intergovernmental organizations, five non-governmental organizations, and several regional, local and private organizations.