This initial volume in the SAGE Series on Green Society provides an overview of the social and environmental dimensions of our energy system, and the key organizations, policy tools, and technologies that can help shape a green-energy economy. Each entry draws on scholarship from across numerous social sciences, natural and physical sciences, and engineering. The urgency of climate change underscores the importance of getting the right technologies, policies and incentives, and social checks-and-balances in place. The green energy challenge faced by our civilization will require many minds and a great effort on all fronts. We hope this collection of articles can provide those with a sparking interest in the topic to participate in what will hopefully become an equitable and intergenerational conversation about the impacts of our energy consumption and how to make it cleaner and greener. Via its 150 signed entries, Green Energy: An A-to-Z Guide provides students, professors, and researchers an invaluable reference, presented in an electronic-only format, to the world's energy future.