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Another method used a trompe to produce compressed air from falling water, which could then be used to power other machinery at a distance from the water.
In hydrology, hydropower is manifested in the force of the water on the riverbed and banks of a river. It is particularly powerful when the river is in flood. The force of the water results in the removal of sediment and other materials from the riverbed and banks of the river, causing erosion and other alterations.
In China and the rest of the Far East, hydraulically operated "pot wheel" pumps raised water into irrigation canals. At the beginning of the Industrial revolution in Britain, water was the main source of power for new inventions such as Richard Arkwright's water frame. Although the use of water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving the bellows in small blast furnaces (e.g. the Dyfi Furnace) and gristmills, such as those built at Saint Anthony Falls, which uses the 50-foot (15 m) drop in the Mississippi River.
In the 1830s, at the peak of the canal-building era, hydropower was used to transport barge traffic up and down steep hills using inclined plane railroads.
The amount of energy, ''E'', released when an object of mass ''m'' drops a height ''h'' in a gravitational field of strength ''g'' is given by
:
The energy available to hydroelectric dams is the energy that can be liberated by lowering water in a controlled way. In these situations, the power is related to the mass flow rate.
:
Substituting ''P'' for and expressing in terms of the volume of liquid moved per unit time (the rate of fluid flow, ''φ'') and the density of water, we arrive at the usual form of this expression:
:
or
A simple formula for approximating electric power production at a hydroelectric plant is:
P = hrgk
where P is Power in kilowatts, h is height in meters, r is flow rate in cubic meters per second, g is acceleration due to gravity of 9.8 m/s2, and k is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher with larger and more modern turbines.
Some hydropower systems such as water wheels can draw power from the flow of a body of water without necessarily changing its height. In this case, the available power is the kinetic energy of the flowing water.
:
where ''v'' is the speed of the water, or with
:
where ''A'' is the area through which the water passes, also
:
Over-shot water wheels can efficiently capture both types of energy.
Category:Sustainable technologies Category:Power station technology Category:Energy conversion Category:Hydraulic engineering
af:Waterkrag ar:طاقة مائية az:Hidroelektrik enerji be:Гідраэнергарэсурсы be-x-old:Гідраэнэргія ca:Energia hidràulica cs:Vodní energie da:Vandkraft de:Wasserkraft es:Energía hidráulica eo:Akvoenergio eu:Energia hidrauliko fa:انرژی آبی fr:Énergie hydraulique gl:Enerxía hidráulica gan:水力 ko:수력 hr:Hidroenergija id:Tenaga air is:Vatnsafl it:Energia idroelettrica he:אנרגיה הידרואלקטרית kk:Гидроэнергия nl:Waterkracht ja:水力 no:Vannkraft nn:Vassenergi pl:Energia wodna pt:Energia hidráulica ro:Energie hidraulică ru:Гидроэнергия simple:Hydropower sk:Vodná energia sl:Vodna energija sr:Хидроенергија sv:Vattenkraft th:พลังงานน้ำ tr:Hidrolik güç uk:Гідроенергетика vi:Thủy năng war:Kusog han tubig zh:水力资源This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
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