Hydroelectricity is a form of hydropower, and is the most widely used form of renewable energy. It produces no waste, and doesn't produce carbon dioxide (CO2) which contributes to greenhouse gases. Hydroelectricity now supplies about 715,000 MWe or 19% of world electricity (16% in 2003), accounting for over 63% of the total electricity from renewables in 2005. Although large hydroelectric installations generate most of the world's hydroelectricity, small hydro schemes are particularly popular i… (More on Hydroelectric)