“Renewable energy technologies” is an umbrella term that stands for energy production using a renewable energy source like solar, wind, water (hydro and tidal), biomass (biofuels and wastes), and geothermal heat. The new generation of renewable energy technologies is covered in this book, including solar energy, wind, marine energy, small hydropower, geothermal energy, biofuels, biogas, and the use of wood as a fossil fuel substitute.