Book excerpt: No segment of the world's economy will be more affected in the drive to reduce greenhouse gas emissions than energy and fuels. The energy sector study, carried out by The Energy and Resources Institute, reviews recent experience in end-use energy efficiency, new technologies, and practices for higher efficiency in fossil fuel energy production as well as ways to expand energy production from renewable sources. Implications for energy security are derived along with recommendations for financing, technology transfer, and associated policy and institutional reforms.