Renewable energy is a fast expanding field, welcomed by many as part of the answer to climate change and energy security concerns, but can renewables deliver enough energy reliably and economically? Rapid expansion continues in the area of renewable energy, with wind capacity expected to double over the next five years and PV solar perhaps treble in the same period. There have been some dramatic projections of potential expansion longer term, with some studies now suggesting that renewables could supply all or nearly all electricity needs globally and perhaps also all energy needs by 2050. In this book, David Elliott conveys the sense of excitement that abounds in this new area of technological development by not only reviewing the basic technological options and how renewable technologies are being implemented and used around the world, but he also considers the problems, including local environmental impacts and the need to deal with the variability of some renewable energy sources. Dividing the renewable energy supply options into those based on mechanical power, heat and light, it also looks at some related energy conversion options, including fuel cells, heat pumps and cogeneration/combined heat and power. The author explores how these new sources can be integrated and used together with technologies for reducing energy waste and demand to replace conventional energy sources and ensure a balance of supply and demand. After reviewing the renewable energy options, the book then considers implementation and policy issues, including storage and grid balancing -- aspects that will play a critical role in the creation of sustainable, clean and viable renewable energy solutions. This is not a text book -- there are plenty available -- instead the book reviews what is happening across this field at this time of great change and rapid development. Supplemented with many case studies and links to information sources, this book will be essential reading for scientists, engineers, policymakers and anybody involved with or interested in the implementation of green and renewable energy technologies, and the environmental aspects of modern energy demands.