Renewable Energy
Hydro Power Station
Alternative energy is any energy that is produced from sources other than fossil fuel energy.
Renewable energy is any source of energy that doesn't consume the finite resources of the Earth and can be easily and quickly replenished.
At present only a small proportion of the world's energy needs come from alternative and renewable energy sources. These exist in many forms including Solar Thermal, Photovoltaics, Wind, Hydro, Tidal/Wave and Bioenergy (including Biomass, Biogas and Biofuels). As with fossil fuels the sun's energy is the ultimate source of these energies.