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Encyclopedia > Hydropower
Undershot water wheels on the Orontes River in Hama, Syria
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Prior to the widespread availability of commercial electric power, hydropower was used for irrigation, and operation of various machines, such as watermills, textile machines, and sawmills. The energy of moving water has been exploited for millennia. In India, water wheels and watermills were built; in Imperial Rome, water powered mills produced flour from grain, and in China and the rest of the Far East, hydraulically operated "pot wheel" pumps that raised water into irrigation canals. 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. Direct mechanical power transmission required that industries using hydropower had to locate near the waterfall. For example, during the last half of the 19th century, many grist mills were built at Saint Anthony Falls, utilizing the 50 foot (15 metre) drop in the really big Mississippi River. The mills contributed to the growth of Minneapolis. Today the largest use of hydropower is for electric power generation, which allows low cost energy to be used at long distances from the water source. For delivered electrical power, see Electrical power industry. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ... Watermill of Braine-le-ChÃ¢teau, Belgium (12th century) A watermill is a structure that uses a water wheel or turbine to drive a mechanical process such as flour or lumber production, or metal shaping (rolling, grinding or wire drawing). ... For other uses, see Textile (disambiguation). ... For the 1922 film starring Oliver Hardy, see The Sawmill. ... An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel (also waterwheel, Norse mill, Persian wheel or noria) is a hydropower system; a system for extracting power from a flow of water. ... Watermill of Braine-le-ChÃ¢teau, Belgium (12th century) A watermill is a structure that uses a water wheel or turbine to drive a mechanical process such as flour or lumber production, or metal shaping (rolling, grinding or wire drawing). ... For other uses, see Roman Empire (disambiguation). ... For other uses, see Canal (disambiguation). ... Self propelled barge carrying bulk crushed stone A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. ... Duquesne Incline, Pittsburgh, Pennsylvania with full length parallel tracks A funicular, also called funicular railway or inclined railway, inclined plane, or in England a cliff railway, consists of a system of transportation in which cables attach to a tram-like vehicle on rails to move it up and down a... Power transmission is the movement of energy from its place of generation to a location where it is applied to performing useful work. ... Gristmill with water wheel, Skyline Drive, VA, 1938 A gristmill is a building where grain is ground into flour. ... Aerial view of Saint Anthony Falls with the upper dam; there is also a lower dam. ... For the river in Canada, see Mississippi River (Ontario). ... This article is about the city in Minnesota. ... For delivered electrical power, see Electrical power industry. ...

## Natural manifestations of hydraulic power GA_googleFillSlot("encyclopedia_square");

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. Water covers 70% of the Earths surface. ... Riverbed may refer to: Stream bed, the channel bottom of a stream or river or creek Wadi, a dry riverbed that contains water only during times of heavy rain Riverbed Technology, an American technology company Category: ... This article or section cites very few or no references or sources. ... For morphological image processing operations, see Erosion (morphology). ...

## Types of water power

There are several forms of water power:

An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel (also waterwheel, Norse mill, Persian wheel or noria) is a hydropower system; a system for extracting power from a flow of water. ... Hydroelectricity is electricity produced by hydropower. ... Tidal power, sometimes called tidal energy, is a form of hydropower that exploits the movement of water caused by tidal currents or the rise and fall in sea levels due to the tides. ... This page is a candidate for speedy deletion. ... Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work - including electricity generation, desalination, and the pumping of water (into reservoirs). ...

### Hydroelectric power

Main article: Hydroelectricity

Hydroelectric power now supplies about 715,000 MWe or 19% of world electricity (16% in 2003). Large dams are still being designed. Apart from a few countries with an abundance of it, hydro power is normally applied to peak load demand because it is readily stopped and started. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations are either already being exploited or are unavailable for other reasons, such as environmental considerations.[citation needed] Hydroelectricity is electricity produced by hydropower. ... Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Kaplan turbine and electrical generator cut-away view. ... This article is about machines that produce electricity. ... MWe and MWt are units for measuring the output of a power plant. ...

Hydropower produces essentially no carbon dioxide or other harmful emissions, in contrast to burning fossil fuels, and is not a significant contributor to global warming through CO2. Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Fossil fuels are hydrocarbon-containing natural resources such as coal, petroleum and natural gas. ...

Hydroelectric power can be far less expensive than electricity generated from fossil fuels or nuclear energy. Areas with abundant hydroelectric power attract industry. Environmental concerns about the effects of reservoirs may prohibit development of economic hydropower sources.

The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water (which provides more flow when it releases). Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. Electricity can be generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.

Not all hydroelectric power requires a dam; a run-of-river project only uses part of the stream flow and is a characteristic of small hydropower projects. Micro hydro in North-West Vietnam Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. ...

### Tidal power

Main article: Tidal power

Harnessing the tides in a bay or estuary has been achieved in France (since 1966), Canada and Russia, and could be achieved in other areas with a large tidal range. The trapped water turns turbines as it is released through the tidal barrage in either direction. Another possible fault is that the system would generate electricity most efficiently in bursts every six hours (once every tide). This limits the applications of tidal energy. Tidal power, sometimes called tidal energy, is a form of hydropower that exploits the movement of water caused by tidal currents or the rise and fall in sea levels due to the tides. ... A Siemens steam turbine with the case opened. ...

### Tidal stream power

A relatively new technology, tidal stream generators draw energy from currents in much the same way that wind generators do. The higher density of water means that a single generator can provide significant power. This technology is at the early stages of development and will require more research before it becomes a significant contributor.

Several prototypes have shown promise. In the UK in 2003, a 300 kW Periodflow marine current propeller type turbine was tested off the coast of Devon, and a 150 kW oscillating hydroplane device, the Stingray, was tested off the Scottish coast. Another British device, the Hydro Venturi, is to be tested in San Francisco Bay.

The Canadian company Blue Energy has plans for installing very large arrays tidal current devices mounted in what they call a 'tidal fence' in various locations around the world, based on a vertical axis turbine design.

### Wave power

Main article: Wave power

Harnessing power from ocean surface wave motion might yield much more energy than tides. The feasibility of this has been investigated, particularly in Scotland in the UK. Generators either coupled to floating devices or turned by air displaced by waves in a hollow concrete structure would produce electricity. Numerous technical problems have frustrated progress. Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work - including electricity generation, desalination, and the pumping of water (into reservoirs). ... For the TV movie also known as The Ocean Waves, see I Can Hear the Sea. ... This article is about machines that produce electricity. ...

A prototype shore based wave power generator is being constructed at Port Kembla in Australia and is expected to generate up to 500 MWh annually. The Wave Energy Converter has been constructed (as of July 2005) and initial results have exceeded expectations of energy production during times of low wave energy. Wave energy is captured by an air driven generator and converted to electricity. For countries with large coastlines and rough sea conditions, the energy of waves offers the possibility of generating electricity in utility volumes. Excess power during rough seas could be used to produce hydrogen. Port Kembla is a seaport near Wollongong, in the Illawarra region of New South Wales, Australia. ...

## Physics

A hydropower resource can be measured according to the amount of available power, or energy per unit time. In large reservoirs, the available power is generally only a function of the hydraulic head and rate of fluid flow. In a reservoir, the head is the height of water in the reservoir relative to its height after discharge. Each unit of water can do an amount of work equal to its weight times the head. In physics, power (symbol: P) is the rate at which work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time. ... In fluid dynamics, head refers to the constant right hand side in the incompressible steady version of Bernoullis equation. ... In fluid dynamics, the rate of fluid flow is the volume of fluid which passes through a given area per unit time. ...

The amount of energy $, E$ released by lowering an object of mass $, m$ by a height $, h$ in a gravitational field is

$, E = mgh$ where $, g$ is the acceleration due to gravity.

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. Hydroelectricity is electricity produced by hydropower. ... Mass flow rate is the movement of mass per time. ...

$frac{E}{t} = frac{m}{t}gh$

Substituting $, P$ for $frac{E}{t}$ and expressing $frac{m}{t}$ in terms of the volume of liquid moved per unit time (the rate of fluid flow $, phi$) and the density of water, we arrive at the usual form of this expression: In fluid dynamics, the rate of fluid flow is the volume of fluid which passes through a given area per unit time. ...

$P = rho, phi, g , h$

For $, P$ in watts, $, rho$ is measured in kg/m³, $,phi$ is measured in m³/s, $, g$ (gee) is measured in m/s², and $, h$ is measured in metres. For other uses, see Watt (disambiguation). ... g (also gee, g-force or g-load) is a non-SI unit of acceleration defined as exactly 9. ... This article is about the unit of length. ...

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. An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel (also waterwheel, Norse mill, Persian wheel or noria) is a hydropower system; a system for extracting power from a flow of water. ... The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ...

$P = frac{1}{2},rho,phi, v^2$ where $, v$ is the velocity of the water,

or with $phi = A, v$ where A is the area through which the water passes, also This article is about velocity in physics. ... This article is about the physical quantity. ...

$P = frac{1}{2},rho, A, v^3.$

Over-shot water wheels can efficiently capture both types of energy.

• (cf cours P. Méderic)'

## Small scale hydro power

Small scale hydro or micro-hydro power has been increasingly used as an alternative energy source, especially in remote areas where other power sources are not viable. Small scale hydro power systems can be installed in small rivers or streams with little or no discernible environmental effect on things such as fish migration. Most small scale hydro power systems make no use of a dam or major water diversion, but rather use water wheels. Micro hydro in North-West Vietnam Small hydro is the application of hydroelectric power on a commercial scale serving a small community or medium sized industry. ... Micro Hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of power. ...

There are some considerations in a micro-hydro system installation. The amount of water flow available on a consistent basis, since lack of rain can affect plant operation. Head, or the amount of drop between the intake and the exit. The more head, the more power that can be generated. There can be legal and regulatory issues, since most countries, cities, and states have regulations about water rights and easements.

Over the last few years, the U.S. Government has increased support for alternative power generation. Many resources such as grants, loans, and tax benefits are available for small scale hydro systems.

In poor areas, many remote communities have no electricity. Micro hydro power, with a capacity of 100 kW or less, allows communities to generate electricity1. This form of power is supported by various organizations such as the UK's Practical Action. Practical Action - the working name of Intermediate Technology Development Group (ITDG) &#8211; is a charity registered in the United Kingdom which works directly in four regions of the developing world &#8211; Latin America, East Africa, Southern Africa and South Asia, with particular concentration on Peru, Kenya, Sudan, Zimbabwe, Sri Lanka...

Micro-hydro power can be used directly as "shaft power" for many industrial applications. Alternatively, the preferred option for domestic energy supply is to generate electricity with a generator or a reversed electric motor which, while less efficient, is likely to be available locally and cheaply.

Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... Micro Hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of power. ... Pico hydro is a term used for hydroelectric power generation of under 5kW. It is useful in small, remote communities that require only a small amount of electricity - for example, to power one or two lightbulbs in a house, or a radio, for part of the day. ... This article or section does not cite any references or sources. ... Deep lake water cooling uses cold water pumped from the bottom of a lake as a heat sink for climate control systems. ... Blue energy is the energy retrieved from the difference in the salt concentration between seawater and river water with the use of osmosis or reverse electro dialysis (RED) with ion specific membranes. ...

## References

• Micro-hydro power, Adam Harvey, 2004, Intermediate Technology Development Group, retrieved 1 January 2005 from http://www.itdg.org/docs/technical_information_service/micro_hydro_power.pdf.
• Microhydropower Systems, U.S. Department of Energy, Energy Efficiency and Renewable Energy, 2005

is the 1st day of the year in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Results from FactBites:

 Hydropower - Wikipedia, the free encyclopedia (1594 words) Hydropower (or waterpower) harnesses the energy of moving or falling water. Prior to the widespread availability of commercial electricity, hydropower was used for milling, textile manufacture, and the operation of sawmills. In the 1830s, at the height of the canal-building era, hydropower was used to transport barge traffic up and down steep hills using the technology of inclined plane railroads.
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