This book is a collection and compilation of various principles of renewable energy technologies and explores how we can use the sun, wind, biomass, geothermal, tidal and water resources to generate energy in a more sustainable form. Each chapter begins with the fundamental theory behind each technology illustrated with clear figures to understand the principle and applications. It also explains the fundamentals of energy, including the transfer of energy, as well as the limitations of natural resources. Starting with solar and wind energy, the text illustrates how energy from the sun, wind and water is transferred and converted into electricity. Other chapters cover methods of energy conversion, biomass energy, biofuel production and other new and renewable sources of energy such as geothermal, hydro, tidal, and ocean energy.