This 2-volume set provides an overview of the global progress in achieving renewable energy goals through sustainable and economically viable means. Volume I presents the background on renewable energy achievements thus far, and the technological, economic and policy challenges to realizing renewable energy goals. This then leads into a discussion of how a transition to a green economy based on renewable energy could be achieved, including global opportunities, trends, policy considerations and societal implications. The book will appeal to academics, industry professionals and policy makers engaged with the energy economy, renewable energy research and environmental sustainability.