Small hydro is the development of hydroelectric power on a scale suitable for local community and industry, or to contribute to distributed generation in a regional electricity grid. Exact definitions vary, but a "small hydro" project is less than 50 megawatts (MW), and can be further subdivide by scale into "mini" (<1MW), "micro" (<100 kW), "pico" (<10 kW). In contrast many hydroelectric projects are of enormous size, such as the generating plant at the Three Gorges Dam at 22,500 megawatts or the vast multiple projects of the Tennessee Valley Authority.
Hydroelectricity, or hydroelectric power, is electricity generated from hydropower. Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. However, when constructed in lowland rainforest areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitted.
The Nurek Dam is an earth-fill embankment dam on the Vakhsh River in Tajikistan. Its primary purpose is hydroelectric power generation and its power station has an installed capacity of 3,015 MW. Construction of the dam began in 1961 and the power station's first generator was commissioned in 1972. The last generator was commissioned in 1979 and the entire project was completed in 1980 when Tajikistan was still a republic within the Soviet Union, becoming the tallest dam in the world at the time. At 304 m (997 ft), it is currently the second tallest man-made dam in the world, after being surpassed by Jinping-I Dam in 2013. The Rogun Dam, also along the Vakhsh in Tajikistan, may exceed it in size when completed.
The Robert Moses Niagara Hydroelectric Power Station is a hydroelectric power station in Lewiston, New York, near Niagara Falls. Owned and operated by the New York Power Authority (NYPA), the plant diverts water from the Niagara River above Niagara Falls and returns the water into the lower portion of the river near Lake Ontario. It uses 13 generators at an installed capacity of 2,525 MW (3,386,000 hp).
The Haditha Dam or Qadisiya Dam is an earth-fill dam on the Euphrates, north of Haditha (Iraq), creating Lake Qadisiyah. The dam is just over 9 kilometres (5.6 mi) long and 57 metres (187 ft) high. The purpose of the dam is to generate hydroelectricity, regulate the flow of the Euphrates and provide water for irrigation. It is the second-largest hydroelectric contributor to the power system in Iraq behind the Mosul Dam.
The Xiaowan Dam is an arch dam on the Lancang (Mekong) River in Nanjian County, Yunnan Province in southwest China. The primary purpose of the dam is hydroelectric power generation and it supports a 4,200 MW power station. Constructed between 2002 and 2010 by Huaneng Power International at a cost of ¥32 billion, it is the world's second highest arch dam at 292 m (958 ft). It is also third highest among dams of all types behind Jinping-I and Nurek and the third largest hydroelectric power station in China.
The Tsankov Kamak Hydroelectric Power Plant, also Tsankov Kamak HPP, comprises an arch dam and hydroelectric power plant (HPP) in Tsankov Kamak, southwestern Bulgaria. It is situated on the Vacha River in Smolyan Province, on the borders of Pazardzhik Province and Plovdiv Province, roughly 40 kilometres (25 mi) southwest of Plovdiv and downstream (north) of the town of Devin. It is a part of the Dospat-Vacha cascade development of the Vacha River involving five dams and power stations within the Devin municipality, 250 kilometres (160 mi) southeast of Sofia. The other four dams are Dospat Dam, Teshel Dam, the Vacha Dam and the Krichim Dam.
The Turkwel Hydroelectric Power Station, also Turkwel Dam, is an arch dam on the Turkwel River about 76 km (47 mi) north of Kapenguria in West Pokot County, Kenya. The dam serves several purposes to include hydroelectric power production, irrigation tourism and fisheries. It was constructed between 1986 and 1991. It supports the third largest hydroelectric power plant in the country, having an installed electric capacity of 106 megawatts (142,000 hp).
The Upper Kotmale Dam is located in Talawakele, within the Nuwara Eliya District, in the Central Province of Sri Lanka. The dam feeds the third largest hydroelectric power station in the country.
The Shamkir reservoir is a large reservoir in the Shamkir Rayon of northwestern Azerbaijan. It is the second largest reservoir in the Caucasus after the Mingachevir reservoir.
The Yantan Dam is a gravity dam on the Hongshui River near Dahua County, Guangxi China. The main purpose of the dam is hydroelectric power production and it has an associated 1,210 MW power station consisting of 4 x 302.5 MW Francis turbine-generators.
The Chirkey Dam is an arch dam on the Sulak River in Dagestan, Russia. The main purpose of the dam is hydroelectric power production, and it supports a 1,000 MW power station. Construction on the dam began in 1964, the first generator was operational by 1974, the last in 1976 while the project was officially completed in 1978. It is the tallest arch dam in Russia.
Stave Falls Dam is a dual-dam power complex on the Stave River in Stave Falls, British Columbia, Canada. The dam was completed in 1912 for the primary purpose of hydroelectric power production. To increase the capacity of Stave Lake, the dam was raised in 1925 and the Blind Slough Dam constructed in an adjacent watercourse 500 m (1,600 ft) to the north, which was the site of the eponymous Stave Falls. In 2000, the dam's powerhouse was replaced after a four-year upgrade. The original Stave Falls powerhouse was once British Columbia's largest hydroelectric power source, and is a National Historic Site of Canada.
The Koteshwar Dam is a gravity dam on the Bhagirathi River, located 22 km (14 mi) downstream of the Tehri Dam in Tehri District, Uttarakhand, India. The dam is part of the Tehri Hydropower Complex and serves to regulate the Tehri Dam's tailrace for irrigation and create the lower reservoir of the Tehri Pumped Storage Power Station. In addition, the dam has a 400 MW run-of-the-river power station. The project was approved in 2000 and its first generator was commissioned on 27 March 2011, the second on 30 March 2011. The construction site had been inundated in September 2010 by floods. The diversion tunnel was later blocked heaving/collapse of the hill in December 2010. The spillway was commissioned in Jan, 2011. The last two generators were made operational in March 2012.
The Okutadami Dam (奥只見ダム) is a concrete gravity dam on the Tadami River, 26 km (16 mi) east of Uonuma on the border of Niigata and Fukushima Prefectures, Japan. The primary purpose of the dam is hydroelectric power generation and it supports a 560 MW power station which is the largest conventional hydroelectric power station in Japan. The dam also forms the second largest reservoir in Japan, next to that of the Tokuyama Dam.
The Lianhua Dam is a concrete-face rock-fill dam on the Mudan River in Linkou County of Heilongjiang Province, China. It is located about 95 km (59 mi) north of Mudanjiang. The 71.8 m (236 ft) tall dam serves several purposes to include hydroelectric power generation, flood control and water supply for irrigation. The dam withholds a large 4,180,000,000 m3 (3,390,000 acre⋅ft) capacity reservoir and supports a 550 MW power station. Construction on the dam began in November 1992 and its first 137.5 MW Francis turbine-generator was operational in December 1996. Two more generators were commissioned on 12 December 1997 and the remaining generator was commissioned on 28 September 1998. It is the first large modern water conservancy project in Heilongjiang. The dam's reservoir displaced 40,000 people and will serve as the lower reservoir for the Huanggou Pumped Storage Power Station when it is complete.
The Vorotan Cascade, or the ContourGlobal Hydro Cascade, is a cascade on the Vorotan River in Syunik Province, Armenia. It was built to produce hydroelectric power and provide irrigation water. The Vorotan Cascade consists of three hydroelectric power plants and five reservoirs with a combined installed capacity of 404.2 MW. It is one of the main power generation complexes in Armenia.
The power generation potential of the rivers in Azerbaijan is estimated at 40 billion kilowatt per hour, and feasible potential is 16 billion kilowatt per hour. Small-scale hydro has significant developmental potential in Azerbaijan. In particular, the lower reaches of the Kura river, the Aras river and other rivers flowing into the Caspian Sea. Hydropower could conceivably provide up to 30% of Azerbaijan’s electricity requirements. Currently, hydropower, dominated by large-scale dams, provides 11.4% of Azerbaijan’s electricity.
The Batak Hydroelectric Cascade is situated in the Pazardzhik Province, southern Bulgaria and is among the first hydroelectric cascades in the country. Inaugurated on 6 September 1959, it includes seven reservoirs and three underground hydro power plants — Batak, Peshtera and Aleko with a combined installed capacity of 254.2 MW, producing an average of 796 GWh annually.
