Water Electricity is electricity obtained from hydropower. Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. Less common variations make use of water's kinetic energy or undammed sources such as tidal power. Hydroelectricity is a renewable energy source.
The energy extracted from water depends not only on the volume but on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is directly proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.
While many supply public power networks, some Water Electricity projects were created for private commercial purposes. For example, aluminium processing requires substantial amounts of power, and in Britain's Scottish Highlands there are examples at Kinlochleven and Lochaber, designed and constructed during the early years of the 20th century. Similarly, the 'van Blommestein' lake, dam and power station were constructed in Suriname to provide power for the Alcoa aluminium industry. In many parts of Canada (the provinces of British Columbia, Manitoba, Ontario, Quebec and Newfoundland and Labrador) hydroelectricity is used so extensively that the word "hydro" is used to refer to any power delivered by a power utility. The government-run power utilities in these provinces are called BC Hydro, Manitoba Hydro, Hydro One (formerly "Ontario Hydro"), Hydro-Québec and Newfoundland and Labrador Hydro respectively. Hydro-Québec is the world's largest hydroelectric generating company, with a total installed capacity (2005) of 31,512 MW.
Water Electricity power supplies 20% of world electricity. Norway produces virtually all of its energy from hydro, while Iceland produces 83% of its requirements (2004), Austria produces 67% of all power generated in the country from hydro (over 70% of its requirements). Canada is the world's largest producer of Water Electricity and produces over 70% of its electric power from hydroelectric sources.
Apart from a few countries with an abundance of it, hydro capacity is normally applied to peak-load demand, because it can be readily stored during off-peak hours (in fact, pumped-storage hydroelectric reservoirs are sometimes used to store power produced by thermal plants for use during peak hours). It is not a major option for the future in the developed countries because most major sites in these countries having potential for harnessing gravity in this way are either being exploited already or are unavailable for other reasons such as environmental considerations.
Regions where thermal plants provide the dominant supply of power utilize Water Electricity to provide the important functions of load following and regulation. This permits thermal plants to be operated closer to thermodynamically optimal points rather than varied continuously, which reduces efficiency and potentially increases pollutant emmissions. Concurrently, hydro plants are then utiliized to provide for hour-to-hour adjustments and to respond to changes in system frequency and voltage (regulation), with no additional economic or environmental effect.
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