Hydroelectricity

Hydroelectricity

Overview


Hydroelectricity is the term referring to electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 generated by hydropower
Hydropower
Hydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...

; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy
Renewable energy
Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

  than fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

 powered energy plants.
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Encyclopedia


Hydroelectricity is the term referring to electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 generated by hydropower
Hydropower
Hydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...

; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy
Renewable energy
Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

  than fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

 powered energy plants. Worldwide, an installed capacity of 1,010 GW
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

 supplied hydroelectricity in 2010. Approximately 16% of the world's electricity is renewable, with hydroelectricity account for 21% of renewable sources and 3.4% of total energy sources.

History


Hydropower has been used since ancient times to grind flour and perform other tasks. In the mid-1770s, French engineer Bernard Forest de Bélidor
Bernard Forest de Bélidor
Bernard Forest de Bélidor was a French engineer, significant to the development of the science of hydraulics....

 published Architecture Hydraulique which described vertical- and horizontal-axis hydraulic machines. By the late 19th century, the electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

 was developed and could now be coupled with hydraulics. The growing demand for the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

 would drive development as well. In 1878 the world's first hydroelectric power scheme was developed at Cragside
Cragside
Cragside is a country house in the civil parish of Cartington in Northumberland, England. It was the first house in the world to be lit using hydroelectric power...

 in Northumberland
Northumberland
Northumberland is the northernmost ceremonial county and a unitary district in North East England. For Eurostat purposes Northumberland is a NUTS 3 region and is one of three boroughs or unitary districts that comprise the "Northumberland and Tyne and Wear" NUTS 2 region...

, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 by William George Armstrong. It was used to power a single arc lamp
Arc lamp
"Arc lamp" or "arc light" is the general term for a class of lamps that produce light by an electric arc . The lamp consists of two electrodes, first made from carbon but typically made today of tungsten, which are separated by a gas...

 in his art gallery. The old Schoelkopf Power Station No. 1 near Niagara Falls
Niagara Falls
The Niagara Falls, located on the Niagara River draining Lake Erie into Lake Ontario, is the collective name for the Horseshoe Falls and the adjacent American Falls along with the comparatively small Bridal Veil Falls, which combined form the highest flow rate of any waterfalls in the world and has...

 in the U.S. side began to produce electricity in 1881. The first Edison hydroelectric power plant, the Vulcan Street Plant
Vulcan Street Plant
The Vulcan Street Plant is the world's first Edison hydroelectric central station. Built on the Fox River in Appleton, Wisconsin, the Vulcan Street Plant was put into operation on September 30, 1882...

, began operating September 30, 1882, in Appleton, Wisconsin
Appleton, Wisconsin
Appleton is a city in Outagamie, Calumet, and Winnebago Counties in the U.S. state of Wisconsin. It is situated on the Fox River, 30 miles southwest of Green Bay and 100 miles north of Milwaukee. Appleton is the county seat of Outagamie County. The population was 78,086 at the 2010 census...

, with an output of about 12.5 kilowatts. By 1886 there were 45 hydroelectric power plants in the U.S. and Canada. By 1889 there were 200 in the U.S. alone.

At the beginning of the 20th century, many small hydroelectric power plants were being constructed by commercial companies in mountains near metropolitan areas. Grenoble
Grenoble
Grenoble is a city in southeastern France, at the foot of the French Alps where the river Drac joins the Isère. Located in the Rhône-Alpes region, Grenoble is the capital of the department of Isère...

, France held the International Exhibition of Hydropower and Tourism
International Exhibition of Hydropower and Tourism
The International exhibition of hydropower and tourism was an exhibition which ran from May 21 to October 25, 1925 in the city of Grenoble in France, in order to dedicate the city, the capital of "white coal".In 1925, Grenoble was the site of an international exhibition on hydroelectric power and...

 with over one million visitors. By 1920 as 40% of the power produced in the United States was hydroelectric, the Federal Power Act
Federal Power Act
The Federal Power Act is a law appearing in Chapter 12 of Title 16 of the United States Code, entitled "Federal Regulation and Development of Power". Enacted as the Federal Water Power Act on June 10, 1920, and amended many times since, its original purpose was to more effectively coordinate the...

 was enacted into law. The Act created the Federal Power Commission
Federal Power Commission
The Federal Power Commission was an independent commission of the United States government, originally organized on June 23, 1930, with five members nominated by the president and confirmed by the Senate...

 to regulate hydroelectric power plants on federal land and water. As the power plants became larger, their associated dams developed additional purposes to include flood control
Flood control
In communications, flood control is a feature of many communication protocols designed to prevent overwhelming of a destination receiver. Such controls can be implemented either in software or in hardware, and will often request that the message be resent after the receiver has finished...

, irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 and navigation. Federal funding became necessary for large-scale development and federally owned corporations, such as the Tennessee Valley Authority
Tennessee Valley Authority
The Tennessee Valley Authority is a federally owned corporation in the United States created by congressional charter in May 1933 to provide navigation, flood control, electricity generation, fertilizer manufacturing, and economic development in the Tennessee Valley, a region particularly affected...

 (1933) and the Bonneville Power Administration
Bonneville Power Administration
The Bonneville Power Administration is an American federal agency based in the Pacific Northwest. BPA was created by an act of Congress in 1937 to market electric power from the Bonneville Dam located on the Columbia River and to construct facilities necessary to transmit that power...

 (1937) were created. Additionally, the Bureau of Reclamation which had began a series of western U.S. irrigation projects in the early 20th century was now constructing large hydroelectric projects such as the 1928 Hoover Dam. The U.S. Army Corps of Engineers was also involved in hydroelectric development, completing the Bonneville Dam
Bonneville Dam
Bonneville Lock and Dam consists of several run-of-the-river dam structures that together complete a span of the Columbia River between the U.S. states of Oregon and Washington at River Mile 146.1. The dam is located east of Portland, Oregon, in the Columbia River Gorge. The primary functions of...

 in 1937 and being recognized by the Flood Control Act of 1936
Flood Control Act of 1936
The Flood Control Act of 1936, , was an Act of the United States Congress signed into law by President Franklin Delano Roosevelt on 22 June 1936. It authorized civil engineering projects such as dams, levees, dikes, and other flood control measures through the United States Army Corps of...

 as the premier federal flood control agency.

Hydroelectric power plants continued to become larger throughout the 20th century. Hydropower was referred to as white coal for its power and plenty. Hoover Dam
Hoover Dam
Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President...

's initial 1,345 MW power plant was the world's largest hydroelectric power plant in 1936; it was eclipsed by the 6809 MW Grand Coulee Dam
Grand Coulee Dam
Grand Coulee Dam is a gravity dam on the Columbia River in the U.S. state of Washington built to produce hydroelectric power and provide irrigation. It was constructed between 1933 and 1942, originally with two power plants. A third power station was completed in 1974 to increase its energy...

 in 1942. The Itaipu Dam opened in 1984 in South America as the largest, producing 14,000 MW but was surpassed in 2008 by the Three Gorges Dam
Three Gorges Dam
The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in the Yiling District of Yichang, in Hubei province, China...

 in China at 22,500 MW. Hydroelectricity would eventually supply some countries, including Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...

, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

 and Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, with over 85% of their electricity. The United States currently has over 2,000 hydroelectric power plants which supply 49% of its renewable electricity.

Generating methods





Conventional (dams)



Most hydroelectric power comes from the potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...

 of dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

med water driving a water turbine
Water turbine
A water turbine is a rotary engine that takes energy from moving water.Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy...

 and generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

. The power extracted from the water depends on the volume and 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
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...

 in water is proportional to the head. A large pipe (the "penstock
Penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....

") delivers water to the turbine.

Pumped-storage


This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently provide the most commercially important means of large-scale grid energy storage
Grid energy storage
Grid energy storage refers to the methods used to store electricity on a large scale within an electrical power grid. Electrical energy is stored during times when production exceeds consumption and the stores are used at times when consumption exceeds production...

 and improve the daily capacity factor
Capacity factor
The net capacity factor or load factor of a power plant is the ratio of the actual output of a power plant over a period of time and its potential output if it had operated at full nameplate capacity the entire time...

 of the generation system.

Run-of-the-river


Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that the water coming from upstream must be used for generation at that moment, or must be allowed to bypass the dam.

Tide


A tidal power
Tidal power
Tidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into useful forms of power - mainly electricity....

 plant makes use of the daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable
Dispatchable generation
Dispatchable generation refers to sources of electricity that can be dispatched at the request of power grid operators; that is, generating plants that can be turned on or off, or can adjust their power output on demand...

 to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

 or undammed sources such as undershot waterwheels
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

.

Underground



An underground power station
Underground power station
An underground power station is a type of hydroelectric power station constructed by excavating the major components from rock, rather than the more common surface-based construction methods....

 makes use of a large natural height difference between two waterways, such as a waterfall or mountain lake. An underground tunnel is constructed to take water from the high reservoir to the generating hall built in an underground cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway.

Large and specialized industrial facilities


Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred megawatts to more than are generally considered large hydroelectric facilities. Currently, only three facilities over are in operation worldwide; Three Gorges Dam
Three Gorges Dam
The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in the Yiling District of Yichang, in Hubei province, China...

 at , Itaipu Dam at , and Guri Dam
Guri Dam
The Guri Dam is a concrete gravity and embankment dam in Bolívar State, Venezuela on the Caroni River. Its official name is Central Hidroeléctrica Simón Bolívar...

 at . Large-scale hydroelectric power stations are more commonly seen as the largest power producing facilities in the world, with some hydroelectric facilities capable of generating more than double the installed capacities of the current largest nuclear power stations.

While many hydroelectric projects supply public electricity networks, some are created to serve specific industrial
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...

 enterprises. Dedicated hydroelectric projects are often built to provide the substantial amounts of electricity needed for aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 electrolytic plants, for example. The Grand Coulee Dam
Grand Coulee Dam
Grand Coulee Dam is a gravity dam on the Columbia River in the U.S. state of Washington built to produce hydroelectric power and provide irrigation. It was constructed between 1933 and 1942, originally with two power plants. A third power station was completed in 1974 to increase its energy...

 switched to support Alcoa
Alcoa
Alcoa Inc. is the world's third largest producer of aluminum, behind Rio Tinto Alcan and Rusal. From its operational headquarters in Pittsburgh, Pennsylvania, Alcoa conducts operations in 31 countries...

 aluminium in Bellingham, Washington
Bellingham, Washington
Bellingham is the largest city in, and the county seat of, Whatcom County in the U.S. state of Washington. It is the twelfth-largest city in the state. Situated on Bellingham Bay, Bellingham is protected by Lummi Island, Portage Island, and the Lummi Peninsula, and opens onto the Strait of Georgia...

, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 for American World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 airplanes before it was allowed to provide irrigation and power to citizens (in addition to aluminium power) after the war. In Suriname
Suriname
Suriname , officially the Republic of Suriname , is a country in northern South America. It borders French Guiana to the east, Guyana to the west, Brazil to the south, and on the north by the Atlantic Ocean. Suriname was a former colony of the British and of the Dutch, and was previously known as...

, the Brokopondo Reservoir
Brokopondo Reservoir
The Brokopondo Reservoir, officially named Professor Doctor Ingenieur W. J. van Blommestein Meer, and also called the Brokopondostuwmeer, is a large reservoir in the South American country Suriname. It is named after the Surakarta-born Dutch hydrological engineer Willem Johan van Blommestein...

 was constructed to provide electricity for the Alcoa
Alcoa
Alcoa Inc. is the world's third largest producer of aluminum, behind Rio Tinto Alcan and Rusal. From its operational headquarters in Pittsburgh, Pennsylvania, Alcoa conducts operations in 31 countries...

 aluminium industry. New Zealand's
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 Manapouri Power Station
Manapouri Power Station
Manapouri Power Station is an underground hydroelectric power station on the western arm of Lake Manapouri in Fiordland National Park, in the South Island of New Zealand...

 was constructed to supply electricity to the aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 smelter at Tiwai Point
Comalco
Rio Tinto Aluminium is now known as Rio Tinto Alcan after Rio's takeover of Alcan. It was the world's eighth largest aluminium company...

.

The construction of these large hydroelectric facilities, and their changes on the environment, are also often on grand scales, creating as much damage to the environment as at helps it by being a renewable resource
Renewable resource
A renewable resource is a natural resource with the ability of being replaced through biological or other natural processes and replenished with the passage of time...

. Many specialized organizations, such as the International Hydropower Association
International Hydropower Association
The International Hydropower Association is a not-for-profit, international organization representing the hydropower sector - focussed in particular on electricity generation, water management, and related industries...

, look into these matters on a global scale.

Small



Small hydro is the development of hydroelectric power on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 megawatts (MW) is generally accepted as the upper limit of what can be termed small hydro. This may be stretched to 25 MW and 30 MW in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Small-scale hydroelectricity production grew by 28% during 2008 from 2005, raising the total world small-hydro capacity to . Over 70% of this was in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 , followed by Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 , the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 , and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 .
Small hydro plants may be connected to conventional electrical distribution networks as a source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a network, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on the balance between stream flow and power production.

Micro


Micro hydro is a term used for hydroelectric power installations that typically produce up to of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel. Micro hydro systems complement photovoltaic
Photovoltaics
Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material...

 solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.

Pico



Pico hydro is a term used for hydroelectric power generation of under . It is useful in small, remote communities that require only a small amount of electricity. For example, to power one or two fluorescent light bulbs and a TV or radio for a few homes. Even smaller turbines of 200-300W may power a single home in a developing country with a drop of only 1 m (3 ft). Pico-hydro setups typically are run-of-the-river, meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream.

Calculating the amount of available power



A simple formula for approximating electric power production at a hydroelectric plant is: , where
  • is Power in watts,
  • is the density of water (~1000 kg/m3),
  • is height in meters,
  • is flow rate in cubic meters per second,
  • is acceleration due to gravity of 9.8 m/s2,
  • is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.


Annual electric energy production depends on the available water supply. In some installations the water flow rate can vary by a factor of 10:1 over the course of a year.

Advantages



Economics


The major advantage of hydroelectricity is elimination of the cost of fuel. The cost of operating a hydroelectric plant is nearly immune to increases in the cost of fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

s such as oil
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

, natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 or coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

, and no imports are needed.

Hydroelectric plants have long economic lives, with some plants still in service after 50–100 years. Operating labor cost is also usually low, as plants are automated and have few personnel on site during normal operation.

Where a dam serves multiple purposes, a hydroelectric plant may be added with relatively low construction cost, providing a useful revenue stream to offset the costs of dam operation. It has been calculated that the sale of electricity from the Three Gorges Dam
Three Gorges Dam
The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in the Yiling District of Yichang, in Hubei province, China...

 will cover the construction costs after 5 to 8 years of full generation.

CO2 emissions


Since hydroelectric dams do not burn fossil fuels, they do not directly produce carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

. While some carbon dioxide is produced during manufacture and construction of the project, this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation. One measurement of greenhouse gas related and other externality comparison between energy sources can be found in the ExternE project by the Paul Scherrer Institut and the University of Stuttgart
University of Stuttgart
The University of Stuttgart is a university located in Stuttgart, Germany. It was founded in 1829 and is organized in 10 faculties....

 which was funded by the European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....

. According to that study, hydroelectricity produces the least amount of greenhouse gases and externality
Externality
In economics, an externality is a cost or benefit, not transmitted through prices, incurred by a party who did not agree to the action causing the cost or benefit...

 of any energy source. Coming in second place was wind
Wind energy
Wind energy is the kinetic energy of air in motion; see also wind power.Total wind energy flowing through an imaginary area A during the time t is:E = ½ m v2 = ½ v 2...

, third was nuclear energy
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, and fourth was solar photovoltaic. The extremely positive greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 impact of hydroelectricity is found especially in temperate climates. The above study was for local energy in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

; presumably similar conditions prevail in North America and Northern Asia, which all see a regular, natural freeze/thaw cycle (with associated seasonal plant decay and regrowth).

Other uses of the reservoir


Reservoirs created by hydroelectric schemes often provide facilities for water sports, and become tourist attractions themselves. In some countries, aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 in reservoirs is common. Multi-use dams
Multipurpose reservoir
- General :Multipurpose reservoirs may be managed to balance some or all of the following activities:*Water supply*Flood control*Soil erosion*Environmental management*Hydroelectric power generation*Navigation*Recreation*Irrigation...

 installed for irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 support agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 with a relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project.

Ecosystem damage and loss of land



Large reservoirs required for the operation of hydroelectric power stations result in submersion of extensive areas upstream of the dams, destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. The loss of land is often exacerbated by the fact that reservoirs cause habitat fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

 of surrounding areas.

Hydroelectric projects can be disruptive to surrounding aquatic ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s both upstream and downstream of the plant site. For instance, studies have shown that dams along the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 and Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 coasts of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 have reduced salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

 populations by preventing access to spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 grounds upstream, even though most dams in salmon habitat have fish ladder
Fish ladder
A fish ladder, also known as a fishway, fish pass or fish steps, is a structure on or around artificial barriers to facilitate diadromous fishes' natural migration. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps into the waters on...

s installed. Salmon spawn are also harmed on their migration to sea when they must pass through turbines
Water turbine
A water turbine is a rotary engine that takes energy from moving water.Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy...

. This has led to some areas transporting smolt downstream by barge
Barge
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...

 during parts of the year. In some cases dams, such as the Marmot Dam, have been demolished due to the high impact on fish. Turbine and power-plant designs that are easier on aquatic life are an active area of research. Mitigation measures such as fish ladders may be required at new projects or as a condition of re-licensing of existing projects.

Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed. For example, in the Grand Canyon
Grand Canyon
The Grand Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Grand Canyon National Park, the 15th national park in the United States...

, the daily cyclic flow variation caused by Glen Canyon Dam
Glen Canyon Dam
Glen Canyon Dam is a concrete arch dam on the Colorado River in northern Arizona in the United States, just north of Page. The dam was built to provide hydroelectricity and flow regulation from the upper Colorado River Basin to the lower. Its reservoir is called Lake Powell, and is the second...

 was found to be contributing to erosion of sand bars. Dissolved oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 content of the water may change from pre-construction conditions. Depending on the location, water exiting from turbines is typically much warmer than the pre-dam water, which can change aquatic faunal populations, including endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

, and prevent natural freezing processes from occurring. Some hydroelectric projects also use canal
Canal
Canals are man-made channels for water. There are two types of canal:#Waterways: navigable transportation canals used for carrying ships and boats shipping goods and conveying people, further subdivided into two kinds:...

s to divert a river at a shallower gradient to increase the head of the scheme. In some cases, the entire river may be diverted leaving a dry riverbed. Examples include the Tekapo
Tekapo River
The Tekapo River flows occasionally through the Mackenzie Basin, Canterbury, in New Zealand's South Island, although the riverbed is now often dry in the upper reaches it maintains a constant flow below the confluence of several tributaries notably the Merryburn, Forks, and Greys streams...

 and Pukaki River
Pukaki River
The Pukaki River flows through the Mackenzie Basin, Canterbury, in New Zealand's South Island.Originally, the river flowed southwest for 15 kilometres from the southern end of Lake Pukaki before joining with the Tekapo River and flowing into the northern end of Lake Benmore...

s in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

Siltation


When water flows it has the ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. Siltation
Siltation
Siltation is the pollution of water by fine particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments, and to the increased accumulation of fine sediments on bottoms where they are undesirable...

 can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become completely full of sediment and useless or over-top during a flood and fail. See Risks to the Glen Canyon Dam
Risks to the Glen Canyon Dam
The Glen Canyon Dam, a concrete arch dam on the Colorado River in the U.S. state of Arizona, has been associated with a large amount of risk, most notably the risk of its siltation and failure...

 for a specific example.

Flow shortage


Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows because of drought, climate change or upstream dams and diversions will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as a result of climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

. Studies from the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 in the United States suggest that modest climate changes, such as an increase in temperature in 2 degree Celsius resulting in a 10% decline in precipitation, might reduce river run-off by up to 40%. Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 in particular is vulnerable due to its heaving reliance on hydroelectricity, as increasing temperatures, lower water flow and alterations in the rainfall regime, could reduce total energy production by 7% annually by the end of the century.

Methane emissions (from reservoirs)


Lower positive impacts are found in the tropical regions, as it has been noted that the reservoirs of power plants in tropical regions may produce substantial amounts of methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

. This is due to plant material in flooded areas decaying in an anaerobic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...

 environment, and forming methane, a potent greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

. According to the World Commission on Dams
World Commission on Dams
The World Commission on Dams was formed in April 1997, to research the environmental, social and economic impacts of the development of large dams globally...

 report, where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant. Although these emissions represent carbon already in the biosphere, not fossil deposits that had been sequestered from the carbon cycle, there is a greater amount of methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

 due to anaerobic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...

 decay, causing greater damage than would otherwise have occurred had the forest decayed naturally.

In boreal reservoirs of Canada and Northern Europe, however, greenhouse gas emissions are typically only 2% to 8% of any kind of conventional fossil-fuel thermal generation. A new class of underwater logging operation that targets drowned forests can mitigate the effect of forest decay.

In 2007, International Rivers
International Rivers
International Rivers is a non-profit, non-governmental, environmental and human rights organization based in Berkeley, California, United States...

 accused hydropower firms of cheating with fake carbon credits under the Clean Development Mechanism
Clean Development Mechanism
The Clean Development Mechanism is one of the "flexibility" mechanisms defined in the Kyoto Protocol . It is defined in Article 12 of the Protocol, and is intended to meet two objectives: to assist parties not included in Annex I in achieving sustainable development and in contributing to the...

, for hydropower projects already finished or under construction at the moment they applied to join the CDM. These carbon credits – of hydropower projects under the CDM in developing countries – can be sold to companies and governments in rich countries, in order to comply with the Kyoto protocol
Kyoto Protocol
The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change , aimed at fighting global warming...

.

Relocation


Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In February 2008 it was estimated that 40-80 million people worldwide had been physically displaced as a direct result of dam construction. In many cases, no amount of compensation can replace ancestral and cultural attachments to places that have spiritual value to the displaced population. Additionally, historically and culturally important sites can be flooded and lost.

Such problems have arisen at the Aswan Dam
Aswan Dam
The Aswan Dam is an embankment dam situated across the Nile River in Aswan, Egypt. Since the 1950s, the name commonly refers to the High Dam, which is larger and newer than the Aswan Low Dam, which was first completed in 1902...

 in Egypt between 1960 and 1980, the Three Gorges Dam in China, the Clyde Dam
Clyde Dam
The Clyde Dam, New Zealand's third largest hydroelectric dam, is built on the Clutha River near the town of Clyde. It is owned and operated by Contact Energy.-History:...

 in New Zealand, and the Ilisu Dam
Ilisu Dam
The Ilisu Dam is an embankment dam under construction on the Tigris River near the village of Ilisu and along the border of Mardin and Sirnak Provinces in Turkey. It is one of the 22 dams of the Southeastern Anatolia Project and its purpose is hydroelectric power production, flood control and...

 in Turkey.

Failure hazard



Because large conventional dammed-hydro facilities hold back large volumes of water, a failure due to poor construction, terrorism, or other cause can be catastrophic to downriver settlements and infrastructure. Dam failures have been some of the largest man-made disasters in history. Also, good design and construction are not an adequate guarantee of safety. Dams are tempting industrial targets for wartime attack, sabotage
Sabotage
Sabotage is a deliberate action aimed at weakening another entity through subversion, obstruction, disruption, or destruction. In a workplace setting, sabotage is the conscious withdrawal of efficiency generally directed at causing some change in workplace conditions. One who engages in sabotage is...

 and terrorism, such as Operation Chastise
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.

The Banqiao Dam
Banqiao Dam
The Banqiao Reservoir Dam is a dam on the River Ru in Zhumadian Prefecture, Henan province, China. It infamously failed in 1975, causing more casualties than any other dam failure in history, and was subsequently rebuilt....

 failure in Southern China directly resulted in the deaths of 26,000 people, and another 145,000 from epidemics. Millions were left homeless. Also, the creation of a dam in a geologically inappropriate location may cause disasters such as 1963 disaster at Vajont Dam
Vajont Dam
The Vajont Dam is a disused dam, completed in 1959 in the valley of the Vajont river under Monte Toc, 100 km north of Venice, Italy...

 in Italy, where almost 2000 people died.

Smaller dams and micro hydro
Micro hydro
Micro hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of electricity. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks....

 facilities create less risk, but can form continuing hazards even after being decommissioned. For example, the small Kelly Barnes Dam
Kelly Barnes Dam
Kelly Barnes Dam was an earthen embankment dam once located in Stephens County, Georgia, just outside of the city of Toccoa. It collapsed on November 6, 1977 after a period of heavy rainfall, and the resulting flood killed 39 people and caused $2.8 million in damages...

 failed in 1967, causing 39 deaths with the Toccoa Flood, ten years after its power plant was decommissioned.

Comparison with other methods of power generation


Hydroelectricity eliminates the flue gas emissions from fossil fuel combustion
Flue gas emissions from fossil fuel combustion
Flue-gas emissions from fossil-fuel combustion refers to the combustion product gas resulting from the much as 10 to 25 volume percent or more of the flue gas. This is closely followed in volume by water vapor created by the combustion of the hydrogen in the fuel with atmospheric oxygen...

, including pollutants such as sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

, nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...

, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, dust, and mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 in the coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

. Hydroelectricity also avoids the hazards of coal mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...

 and the indirect health effects of coal emissions. Compared to nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, hydroelectricity generates no nuclear waste, has none of the dangers associated with uranium mining
Uranium mining
Uranium mining is the process of extraction of uranium ore from the ground. The worldwide production of uranium in 2009 amounted to 50,572 tonnes, of which 27% was mined in Kazakhstan. Kazakhstan, Canada, and Australia are the top three producers and together account for 63% of world uranium...

, nor nuclear leaks
Nuclear and radiation accidents
A nuclear and radiation accident is defined by the International Atomic Energy Agency as "an event that has led to significant consequences to people, the environment or the facility...

. Unlike uranium, hydroelectricity is also a renewable energy source.

Compared to wind farm
Wind farm
A wind farm is a group of wind turbines in the same location used to produce electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other...

s, hydroelectricity power plants have a more predictable load factor. If the project has a storage reservoir, it can generate power when needed. Hydroelectric plants can be easily regulated to follow variations in power demand.

Unlike fossil-fuelled combustion turbines, construction of a hydroelectric plant requires a long lead-time for site studies, hydrological studies, and environmental impact assessment. Hydrological data up to 50 years or more is usually required to determine the best sites and operating regimes for a large hydroelectric plant. Unlike plants operated by fuel, such as fossil or nuclear energy, the number of sites that can be economically developed for hydroelectric production is limited; in many areas the most cost-effective sites have already been exploited. New hydro sites tend to be far from population centers and require extensive transmission lines. Hydroelectric generation depends on rainfall in the watershed, and may be significantly reduced in years of low rainfall or snowmelt. Long-term energy yield may be affected by climate change. Utilities that primarily use hydroelectric power may spend additional capital to build extra capacity to ensure sufficient power is available in low water years.

World hydroelectric capacity


The ranking of hydro-electric capacity is either by actual annual energy production or by installed capacity power rating. A hydro-electric plant rarely operates at its full power rating over a full year; the ratio between annual average power and installed capacity rating is the capacity factor
Capacity factor
The net capacity factor or load factor of a power plant is the ratio of the actual output of a power plant over a period of time and its potential output if it had operated at full nameplate capacity the entire time...

. The installed capacity is the sum of all generator nameplate power ratings. Sources came from BP Statistical Review - Full Report 2009

Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

, Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

, and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

 are the only countries in the world where the majority of the internal electric energy production is from hydroelectric power. Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

 produces 100% of its electricity from hydroelectric dams, and exports 90% of its production to Brazil and to Argentina. Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 produces 98–99% of its electricity from hydroelectric sources.
Ten of the largest hydroelectric producers as at 2009.
Country Annual hydroelectric
production (TWh
TWH
TWH or twh could refer to:*Tennessee Walking Horse, a breed of horse* Toronto Western Hospital, a hospital in Toronto, Canada* TWH Bus & Coach, a bus company in Romford, England* Terrawatt-hour, measure of electrical energy, 1012 watt-hours...

)
Installed
capacity (GW)
Capacity
factor
% of total
capacity
 Mainland China 652.05 196.79 0.37 22.25
 Canada 369.5 88.974 0.59 61.12
 Brazil 363.8 69.080 0.56 85.56
 United States 250.6 79.511 0.42 5.74
 Russia 167.0 45.000 0.42 17.64
 Norway 140.5 27.528 0.49 98.25
 India 115.6 33.600 0.43 15.80
 Venezuela 85.96 14.622 0.67 69.20
 Japan 69.2 27.229 0.37 7.21
 Sweden 65.5 16.209 0.46 44.34

Major projects under construction

Name Maximum Capacity Country Construction started Scheduled completion Comments
Xiluodu Dam
Xiluodu Dam
The Xiluodu Dam is a hydroelectric dam project on the Jinsha River, i.e. the upper course of the Yangtze River in China. In early 2005, the Chinese government halted the construction due to lack of environmental impact studies. Later, construction was restarted. If completed, the Xiluodu Dam will...

12,600 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

December 26, 2005 2015 Construction once stopped due to lack of environmental impact study.
Belo Monte Dam
Belo Monte Dam
The Belo Monte Dam is a proposed hydroelectric dam complex on the Xingu River in the state of Pará, Brazil...

11,181 MW Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

March, 2011 2015 Preliminary construction underway.
Siang Upper HE Project 11,000 MW India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

April, 2009 2024 Multi-phase construction over a period of 15 years. Construction was delayed due to dispute with China.
TaSang Dam
TaSang Dam
The TaSang Dam is a planned multi-purpose dam on the Salween River in the Shan State, Burma. The TaSang dam’s location will be northeast of Rangoon and west of Mongtong. The TaSang Dam will be the first dam on the Salween River and will be the largest hydroelectric dam in Burma and the...

7,110 MW Burma March, 2007 2022 Controversial 228 meter tall dam with capacity to produce 35,446 Ghw annually.
Xiangjiaba Dam
Xiangjiaba Dam
The Xiangjiaba Dam is a large hydroelectric dam on the Jinsha River, a tributary of the Yangtze River in Yunnan Province and Sichuan Province, southwest China. The facility runs on eight turbines, each with a capacity of , totalling the generating capacity to . When completed, it will be the...

6,400 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

November 26, 2006 2015
Nuozhadu Dam
Nuozhadu Dam
Nuozhadu Dam is an under construction embankment dam on the Lancang River in Yunnan Province, southwest China. The dam will be tall, and will create a reservoir with a normal capacity of at a level of asl. The purpose of the dam is hydroelectric power production along with flood control and...

5,850 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

2006 2017
Jinping 2 Hydropower Station 4,800 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

January 30, 2007 2014 To build this dam, 23 families and 129 local residents need to be moved. It works with Jinping 1 Hydropower Station as a group.
Jinping 1 Hydropower Station 3,600 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

November 11, 2005 2014
Jirau Dam
Jirau Dam
The Jirau Dam is a hydroelectric dam currently under construction on the Madeira River in the state of Rondônia, Brazil.The dam is part of a planned four power plant Madeira river hydroelectric complex, which will consist of two dams in Brazil , a third on the border of Brazil and Bolivia,...

3,300 MW Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

2008 2012 Construction halted in March 2011 due to worker riots.
Santo Antônio Dam
Santo Antônio Dam
The Santo Antônio Dam is an under construction hydroelectric dam on the Madeira River southwest of Porto Velho in the state of Rondônia, Brazil....

3,150 MW Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

September 2008 2011 Run-of-the-river project
Pubugou Dam
Pubugou Dam
The Pubugou Dam is concrete face rock-fill embankment dam on the Dadu River, a tributary of the Yangtze River in Sichuan Province...

3,300 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

March 30, 2004 2010
Goupitan Dam
Goupitan Dam
The Goupitan Dam is an under construction concrete arch dam on the Wujiang River, a tributary of the Yangtze River in Guizhou Province, southwest of China. The dam's hydroelectric facility will operate on five turbines, each with a hydroelectric generating capacity of , for a total of ....

3,000 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

November 8, 2003 2011
Guanyinyan Dam
Guanyinyan Dam
The Guanyinyan Dam is an under construction gravity dam on the Jinsha River southwest of Panzhihua on the border of Yunnan and Sichuan Provinces in China. The purpose of the dam is hydroelectric power generation and flood control. Construction on the dam started in 2008 and the river was diverted...

3,000 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

2008 2015 Construction of the roads and spillway started.
Lianghekou Dam
Lianghekou Dam
The Lianghekou Dam is an under construction concrete face rock-fill embankment dam on the Yalong River in Yajiang County, Sichuan Province, China. The dam is located at the confluence of the Yalong, Xianshui and Qingda Rivers. The dam will be tall and support a 3,000 MW power station...

3,000 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

2009 2015
Boguchan Dam 3,000 MW Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

1980 2013
Dagangshan Dam
Dagangshan Dam
The Dagangshan Dam is an under construction arch dam on the Dadu River near the village of Dagangshan in Sichuan Province, China. The dam will house a hydroelectric power station with 4 x 650 MW generators for a total installed capacity of 2,600 MW...

2,600 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

August 15, 2008 2014
Sơn La Dam
Sơn La Dam
Sơn La Dam is a concrete gravity dam on the Da River in It Ong municipality, Mường La District, Sơn La Province, Vietnam. When fully operational, it will become largest hydroelectric power station in Southeast Asia.-History:The project was proposed in 1970s...

2,400 MW Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

December 2, 2005 2012
Guandi Dam
Guandi Dam
The Guandi Dam is an under construction gravity dam on the Yalong River, a tributary of the Yangtze River in Sichuan Province Southwest of China. It supplies water to four hydroelectric generators, each with generating capacity of 600 MW. The total generating capacity of the project is 2,400 MW....

2,400 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

November 11, 2007 2012
Liyuan Dam
Liyuan Dam
The Liyuan Dam is an under construction concrete face rock-fill embankment dam on the Jinsha River on the border of Yulong County and Shangri-La County, Yunnan Province, China. The dam will have an associated hydroelectric power station with a 2,400 MW power station containing 4 x 600 MW generators...

2,400 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

2008
Tocoma Dam
Tocoma Dam
The Manuel Piar Hydroelectric Power Plant is under construction and it is the last hydroelectric development project in the Lower Caroní River Basin. The project includes the installation of 2,160 MW to generate an annual average energy of 12,100 GWh...

 Bolívar State
Bolívar (state)
Bolívar State , is one of the 23 states into which Venezuela is divided. The state capital city is Ciudad Bolívar. Bolívar State covers a total surface area of 238,000 km² and in June 30, 2010 had an estimated population of 1,620,359....

2,160 MW Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

2004 2014 This power plant would be the last development in the Low Caroni Basin, bringing the total to six power plants on the same river, including the 10,000MW Guri Dam.
Ludila Dam
Ludila Dam
The Ludila Dam is an under construction gravity dam on the Jinsha River near Lijiang in Yunnan province, China. Construction on the dam began in 2007 and was halted in June 2009 by the Ministry of Environmental Protection after it was being constructed without approval. An estimated 16,900 people...

2,100 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

2007 2015 Construction halt due to lack of the evnironmental assessment.
Shuangjiangkou Dam
Shuangjiangkou Dam
The Shuangjiangkou Dam, also referred to as Shuang Jiang Kou, is an under construction embankment dam on the Dadu River in Sichuan Province, China. When completed, the tall dam will be the tallest in the world. Preliminary construction began in 2008 and is expected to be complete in 2012. By April...

2,000 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

December, 2007 The dam will be 312 m high.
Ahai Dam
Ahai Dam
The Ahai Dam is an under construction gravity dam on the Jinsha River in Yulong County, Lijiang Prefecture and in the river reach at about 5 km in the lower reaches of Cuiyu river mouth.-Situation:...

2,000 MW China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

July 27, 2006
Lower Subansiri Dam 2,000 MW India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

2005 2012

See also

  • Hydraulic engineering
    Hydraulic engineering
    This article is about civil engineering. For the mechanical engineering discipline see Hydraulic machineryHydraulic engineering as a sub-discipline of civil engineering is concerned with the flow and conveyance of fluids, principally water and sewage. One feature of these systems is the extensive...

  • List of hydroelectric power stations
  • List of hydroelectric power station failures
  • Xcel Energy Cabin Creek Hydroelectric Plant Fire
    Xcel Company Fire
    The Xcel Energy Cabin Creek Fire occurred on October 2, 2007 The incident occurred at Xcel Energy’s Hydropower Generation plant in Georgetown, Colorado, a small town forty-five miles west of Denver. This accident killed five workers and injured three...


External links