Hydroelectric Power
Ånund Killingtveit
Abstract
Hydroelectric power (hydropower) is a renewable energy source where electrical power is derived from the energy of water moving from higher to lower elevations. It is a proven, mature, predictable, and price-competitive technology. Hydropower has among the best conversion efficiencies of all known energy sources (about 90% efficiency, water to wire). It requires relatively high initial investment, but has a long life span with very low operation and maintenance costs. The existing hydropower system has an annual generation capacity of 4100 TWh a−1 and contributes to almost 17% of the annual electricity generation, worldwide. There is still a large potential for further development, as the total technical potential has been estimated to be roughly 16,000 TWh. Out of this, about 9600 TWh has been classified as economical potential. In Europe, close to 50% of technical potential has already been developed, while in Asia 24% and in Africa only 6%. Significant potential can also be found in existing infrastructure that currently lacks generating units (e.g., existing barrages, weirs, dams, canal fall structures, water supply schemes) by adding new hydropower facilities. Only 25% of the existing 45,000 large dams in the world are currently used for hydropower, and the other 75% are used exclusively for other purposes (e.g., irrigation, flood control, navigation, and urban water supply schemes). Hydropower offers significant potential for carbon emissions reductions, as greenhouse gas emissions are generally very low, typically less than 1% of that from coal power plants. Hydropower is cost competitive, with LCOE typically in the range of 2–10 US c.(kWh)−1, which is comparable with the cost of energy from thermal power plants. Hydropower has an energy payback ratio of 200–300, highest of all types of renewable energies. Hydropower can provide both energy and water management services and also help to support other variable renewable energy sources such as wind and solar, by providing storage and load balancing services.