water power

water power mechanical energy derived from falling or flowing water, e.g., rivers, streams, and the overflow of dams. The wooden water wheel , long utilized for driving machinery in flour mills and factories, was largely supplanted by the steam engine in the early 19th cent. In modern practice, water flowing from a higher level to a lower level (as from a dam or waterfall) is used to activate a turbine that drives an electric generator, a process called hydroelectric power generation. The amount of power furnished is proportional to the rate of flow of the water and the vertical distance through which it falls. In a pumped-storage plant, water is pumped upward to a high-level reservoir during periods of low electricity demand by using the excess electricity available. During periods of high demand the facility produces electricity by using the water that flows down from the reservoir. The availability of water power along a fall line, which is a boundary between an upland region and a coastal plain, influenced the location of many cities in the E United States. Similarly, Canada, Norway, Sweden, and Switzerland, which have mountainous regions subject to heavy rainfall near industrialized areas, have highly developed hydroelectric programs. Asia, South America, and Africa have the greatest potential for further water power development, the nations of Europe and North America having developed their resources to the greatest extent. In the late 1990s the countries that produced the most hydroelectric power—about 51 percent of the world total—were the United States, Canada, Brazil, China, and Russia. For information on some important hydroelectric power projects, see Churchill Falls ; Niagara Falls ; Columbia basin project ; Colorado River storage project ; Saint Lawrence Seaway ; Tennessee Valley Authority ; Dniprohes .

water power power that is derived from the weight or motion of water, used as a force to drive machinery.
water-powered adj.

water power in Ireland can be traced back to the early Christian era. Then it was employed in grinding grain for family use. Primitive mills, powered by waterwheels, were usually sited along a small mountain water course. Many monastic settlements had water‐powered grain mills. The waterwheels had their paddles set horizontally to catch the flow of water. They were attached to millstones which were turned to grind the grain. Some have been dated between ad 630 and ad 926. Water power technology remained at this level until the early 17th century plantations. Settlers brought with them new developments in water power from Great Britain and the Continent. These were introduced or adapted to tasks previously performed by humans or animals. Among these improvements was the now familiar vertical waterwheel.

Water power was vital for industrialization, in a country largely devoid of coal and iron. In 1870 it provided one‐quarter of Ireland's recorded horsepower, compared to one‐twentieth of Great Britain's. The drawback of water power is that its user can be at the mercy of floods and frost in winter or droughts in summer. Its use was greatest in Ulster, particularly in the development of the linen industry, from the first quarter of the 18th century. Then water was used in flax scutching mills, and in beetling mills, wash mills, and for rubbing boards in the bleaching process. In the 19th century, mechanized spinning and powerloom weaving were driven by water as well as steam. Many model mill villages were specifically built on sites suitable for the exploitation of their water power resource. The Ordnance Survey maps of the 19th century show an extensive network of rural mills, of every kind, powered by water. The main types were flour mills, threshing mills, spade mills, saw mills, and paper mills.

The turbine, pioneered by an Ulsterman, James Thomson, brother of Lord Kelvin and professor of engineering at Queen's University 1854–73, was a significant development, making water power much more effective and removing the need for large waterwheels. Turbines in turn made possible the generation of electricity by hydroelectric power. This was used from the end of the 19th century to run trams from Bessbrook to Newry in Co. Down and from Portrush, Co. Antrim, to the nearby tourist attraction of the Giant's Causeway. Later the same technology became the major source of electricity in southern Ireland, through the Shannon Hydroelectric Scheme at Ardnacrusha.

Bibliography

Coe, W. E. , The Engineering Industry of the North of Ireland (1969)

Peter Collins