Direct or indirect energy from the sun can be transformed into electricity via a number of alternative and renewable sources. Electrical energy can be produced from Wind, Hydro, Tidal and Wave Energy, Photo-voltaic Cells, Solar Thermal and Bioenergy (Biomass and Biogas) cogeneration facilities.
The natural conversion of solar energy occurs in the earth's atmosphere, oceans, and plant life. Interactions between the sun's energy and the atmosphere produce the winds, which have been used for years to power sailing ships and drive wind mills. Today we can use wind energy to produce electricity from wind turbines. About 2% of solar energy reaching earth is converted into wind energy.
The interaction between solar heat energy and our oceans drives the hydrological cycle. Approximately 30% of the solar energy reaching our atmosphere drives this "water" cycle, which produces rainfall and the potential energy of water in mountain streams and rivers. The power produced by these flowing waters as they pass through modern turbines is called hydroelectric power. The rivers flow to the sea where the tides and the waves could also be harnessed to produce electrical power.
Through the process of photosynthesis, solar energy contributes to the growth of plant life (biomass) that can be used as fuel, including wood and the fossil fuels that are derived from geologically ancient plant life. Fuels such as alcohol or methane can also be extracted from biomass as biogas.
The amount of solar energy reaching the earth's surface is 6000 times the amount of energy used by all human beings worldwide.