Hydroelectricity is a form of hydropower, and is the most widely used form of renewable energy. It produces no waste, and does not 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.

Water scarcity concerns are often used to dismiss out-of-hand the potential for hydropower in South Africa. In reality, energy derived from extracting the potential energy of elevated water during its descent has an important role to play. This is especially important when one considers the huge volumes of water that are moved around the country in balancing the supply and demand for water, and the fact that the energy content of this water is seldom considered.