(→‎Big and small: Moved "Use of hydroelectric plants depending on size" section from Microhydro)
(→‎Use: moved "Small hydropower plants" section from Hydropower)
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See [[Alternatives to hydroelectric energy]].
See [[Alternatives to hydroelectric energy]].
==Small hydropower plants==
===parameters for the determination of a project===
Today, to transform  hydropower to electrical power, it is possible to construct very large but also small-sized plants. This article lists the parameters to determine small hydroelectric facilities. They have a place in the process of the development of small communities and in the process of [[sustainable development]] because of the economy in terms of CO²-emissions. See http://www.kuleuven.ac.be-ei-public-publications-EIWP900-09_fr.pdf
===Vocabulary and definitions===
Classes of powerplants: The technical literature considers small power plants, those plants that generate a power output less than 2000kW or 2 MW. The small power plants are divided into mini power (maximum power output 500kW), micro-power (maximum power output of 100 kW) and pico-power (0.2 kw to 5kW). These powers outputs are to be considered as orders of magnitude because, depending on the country or region, different figures have been cited. The pico-plants have been installed mostly in Asia, Vietnam (120,000) and the Philippines.
{| border="1" cellpadding="5" cellspacing="0" style="text-align:left"
|Country|| Micro (kW)|| Mini (kW)|| Small (MW) || Source
|-
|United States|| <100|| 100-1000 || 1-30|| Dragu, 2002
|-
|China|| <500|| -|| 0,5-25|| Dragu, 2002
|-
|Italy|| -|| -|| <3|| European Commission, 2000
|-
|Portugal,Spain, Ireland, Greece, Belgium|| -|| -|| <10|| European Commission, 2000
|-
|France|| 5-5000|| -|| <8|| European Commission, 2000
|-
|India|| <100|| 101-1000||1-1,5|| Dragu,2002
|-
|ESHA-European Small Hydropower Association|| <100|| 101-500|| 0,5-10|| ESHA,1998
|-
|}
<ref>[http://www.terme.ucl.ac.be/recherche/tractebel/WP5-TERM.pdf Reference]</ref>


==Use==
==Use==

Revision as of 15:22, 21 March 2013

Hydroelectric power, or hydropower, is an established and reliable form of renewable energy. It uses the natural water cycle, and gravity, to generate electricity.

Rural applications in the developing world

The use of water power in the People's Republic of China has reflected the same pattern, with first water wheels and then turbines being built in great numbers as power demands increased along with technical production capabilities. By 1976 an estimated 60,000 small hydroelectric turbines were in operation in South China alone, contributing a major share of the electricity used by rural communes for lighting, small industrial production, and water pumping.

With the rising cost of energy in the United States today, small hydroelectric units are returning in large numbers. Generating stations along New England rivers are being rehabilitated and put back into operation. The number of companies making small waterpower units has jumped. The U.S. Department of Energy has estimated that 50,000 existing agricultural, recreational, and municipal water supply reservoirs could be economically equipped with hydroelectric generating facilities.

In developing countries, the potential for small hydropower installations has never carefully been measured. Past surveys of hydropower potential have focused on possible sites for large dams, as small hydroelectric units were considered uneconomical or ill-suited to the goal of providing large blocks of electric power for cities, industrial estates, or aluminum production. With the rapidly increasing costs of energy, however, the economics are now much more favorable for small hydroelectric units, which are also well-suited to the needs of small rural communities, and do not bring the degree of environmental disruption associated with large reservoirs. Many small units do not require reservoirs at all, and use small diversion canals instead.

The success of waterpower installations can be greatly affected by forest conservation practices in the watershed above. Rapid deforestation brings high rates of soil erosion and subsequent rapid silt filling of reservoirs behind dams. At the same time, greater rain runoff causes increasingly violent floods that threaten hydropower installations. During the months following the floods, low water flows are likely to reduce generating capacity. A program to protect the watershed and the construction of a diversion canal may be necessary to prevent damage to a small waterpower installation.

Method

A large scale hydroelectric power plant forces water, generally held in a dam, through a hydraulic turbine connected to a generator. After the water exits the turbine it returns to the stream or river below the dam.

Because of the dependence on gravity, hydroelectric power is generally more feasible in mountainous regions than in flat country.

Hydroelectricity has relatively low operations and maintenance costs, especially compared to other forms of renewable energy.

Reliability

Hydroelectricity is a long-established technology, and the process itself is very reliable.

However, hydropower is highly dependent upon precipitation (rain and snow) - droughts can effect generating capacity.

Environmental impact

Hydroelectricity has very little impact on air pollution and climate change, as no fuel is burned. However, vegetation in the flood zone when the dam is built will decay in the lake formed by the dam, releasing methane. The net result is still believed to be a very small amount of greenhouse gases for the electricity produced, but it will vary from dam to dam.

The ecological effects of a dam on the downstream side of the structure, however, can be severe, as the water restriction often dramatically changes the normal flow of the river or stream. The range of anadromous fish (such as salmon) upriver is understandably hampered by the concrete and turbines of dams, beyond which is a habitat that has been deprived of a main predator. The buildup of sediment and silt behind the dam can substantially alter the geology of the downstream reaches.

The problems with dams

The largest impact of hydropower is generally from the dam. To avoid the serious negative impacts of a dam, a "run of the river" design is far preferable.

See Alternatives to hydroelectric energy.

Small hydropower plants

parameters for the determination of a project

Today, to transform hydropower to electrical power, it is possible to construct very large but also small-sized plants. This article lists the parameters to determine small hydroelectric facilities. They have a place in the process of the development of small communities and in the process of sustainable development because of the economy in terms of CO²-emissions. See http://www.kuleuven.ac.be-ei-public-publications-EIWP900-09_fr.pdf

Vocabulary and definitions

Classes of powerplants: The technical literature considers small power plants, those plants that generate a power output less than 2000kW or 2 MW. The small power plants are divided into mini power (maximum power output 500kW), micro-power (maximum power output of 100 kW) and pico-power (0.2 kw to 5kW). These powers outputs are to be considered as orders of magnitude because, depending on the country or region, different figures have been cited. The pico-plants have been installed mostly in Asia, Vietnam (120,000) and the Philippines.

Country Micro (kW) Mini (kW) Small (MW) Source
United States <100 100-1000 1-30 Dragu, 2002
China <500 - 0,5-25 Dragu, 2002
Italy - - <3 European Commission, 2000
Portugal,Spain, Ireland, Greece, Belgium - - <10 European Commission, 2000
France 5-5000 - <8 European Commission, 2000
India <100 101-1000 1-1,5 Dragu,2002
ESHA-European Small Hydropower Association <100 101-500 0,5-10 ESHA,1998

[1]

Use

Use of hydroelectric plants depending on size

Template:Hl3 align="center"|Size Template:Hl3 align="center"|Power Output Template:Hl3 align="center"|Typical Use
Large >10MW Usually part of a large grid.
Small 1MW-10MW Usually grid intertied. (up to 50MW in Canada[2])
Mini 100kW-1,000kW (1MW) Community and industry. Often grid intertied.
Micro 1kW-100kW Small low energy consuming community, small industry, rural high energy consuming household. Usually off-grid.
Pico <1kW Radio tower, low energy consuming household, charging station. Almost always off grid.

Please note that these are averages, many different communities classify hydropower somewhat differently.

Big and small

Microhydro is relatively simple and affordable technology used to provide power to a community. However, this is still many thousands of dollars, typically.

Picohydro refers to tiny generators, possibly made from old car alternators, generating power from a stream of water flowing through a large plastic bucket.

The future of hydroelectricity

The ability to build new generating capacity is extremely limited, especially in developed countries, because:

  • Most suitable sites are already being used.
  • Building a dam is extremely controversial, guaranteed to face strong opposition from environmental groups and owners of affected farms and other property. In practice, only an authoritarian government is likely to choose to build a new dam. In other cases, new capacity must be in the form of smaller "run of the river" systems.

See also


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