ABSTRACT
As their name implies, renewable energy sources are essentially inexhaustible and may provide energy for several millennia. Hydraulic (hydroelectric or hydro), solar wind, biomass, and geothermal energies are the most widely used of the renewable energy sources. Less frequently used forms are tidal, wave, sea current, and ocean–thermal energy conversion. Renewable energy sources pose a lesser threat to the environment and ecosystems than the other energy sources; they do not contribute to global warming and, for this reason, have been at the forefront of development since 2000. In particular, solar and wind energy systems for the production of electricity as well as solar energy for space heating and water have grown very rapidly in the period of 2010–2015. The first table in this chapter gives the existing global capacity at the end of 2015 and the annual globally averaged growth rate of the capacity of renewable energy installations (REN21, Renewables 2016 Global Status Report, REN21 Secretariat, Paris, 2016).
