With shortages of fossil energy and heavy biomass energy use occurring in both developed and developing countries, a major focus has developed worldwide on renewable energy systems. Currently, a heavy focus is on biofuels made from crops, crop residues and wood. Though it may seem beneficial to use renewable plant materials for biofuel, their use raises many concerns about major environmental problems, including food shortages and serious destruction of vital soil resources. All renewable energy systems need to be investigated because humankind has limited oil, gas and coal reserves remaining. In addition, coal will become increasingly difficult to extract and will greatly increase the global warming threat. Serious energy conservation and research on viable renewable energy technologies are needed. This book considers the effectiveness and economics of several renewable energy technologies of current interest, including biofuels, solar and wind.