Hydroelectricity, or hydroelectric power, is electricity generated from hydropower. Hydropower supplies one sixth of the world's electricity, almost 4,500 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.
Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amount of storage, in which case the storage reservoir is referred to as pondage. A plant without pondage is subject to seasonal river flows, so the plant will operate as an intermittent energy source. Conventional hydro uses reservoirs, which regulate water for flood control, dispatchable electrical power, and the provision of fresh water for agriculture.
The Wudongde Dam is a large hydroelectric dam on the Jinsha River, an upper stretch of Yangtze River in Sichuan and Yunnan provinces in southwest China.
According to the International Hydropower Association, Canada is the fourth largest producer of hydroelectricity in the world in 2021 after the United States, Brazil, and China. In 2019, Canada produced 632.2 TWh of electricity with 60% of energy coming from Hydroelectric and Tidal Energy Sources).
India is 5th globally for installed hydroelectric power capacity. As of 31 March 2020, India's installed utility-scale hydroelectric capacity was 46,000 MW, or 12.3% of its total utility power generation capacity. Additional smaller hydroelectric power units with a total capacity of 4,683 MW have been installed. India's hydroelectric power potential is estimated at 148,700 MW at 60% load factor. In the fiscal year 2019–20, the total hydroelectric power generated in India was 156 TWh with an average capacity factor of 38.71%.
The Shuangjiangkou Dam, also referred to as Shuang Jiang Kou, is an embankment dam currently being constructed in a gorge on the Dadu River in Sichuan Province, China. When completed, the 312 m-tall (1,024 ft) dam will be the tallest dam in the world. Preliminary construction began in 2008 and the entire project was expected to be complete in 2018. By April 2011, over 200,000,000 m3 (261,590,124 cu yd) of material had been excavated from the construction site. In March 2013, China's Ministry of Environmental Protection approved construction on the dam's superstructure and associated facilities. The government acknowledged that the dam would have negative impacts on the environment but that developers were working to mitigate them. The dam is being built by the Guodian Group at a cost of US$4.02 billion. The entire construction period is expected to last 10 years. All turbines are expected to be commissioned by 2023.
The Lianghekou Dam is a clay-core rockfill Embankment dam currently in operation on the Yalong River, a tributary of Yangtze River, in Yajiang County, Sichuan Province, China. The dam is located at the confluence of the Yalong, Xianshui and Qingda Rivers. The 295 m (968 ft) tall dam is the highest embankment dam in the country and support a 3,000 MW power station. Studies for the dam were completed between 2005 and 2009 with preliminary construction beginning that year. Major works on the dam officially began in October 2014. The first two generators were commissioned in September 2021 and the final unit was put in service in March 2022. With the reservoir's relatively large active capacity with respect to the river's annual flow, it can regulate the river flow across multiple years and increase the downstream hydroelectric power stations' output by smoothing out river flow peaks and troughs.
The Ichari Dam is a concrete gravity dam on the Tons River 13 km (8 mi) north of Dakpathar in Uttarakhand, India. The primary purpose of the dam is hydroelectric power production and it is a run-of-the-river-type. It was completed in 1972. The dam diverts water to the Chibro Power Station which is then returned to the Tons River before being fed to the Khodri Power Station.
The Dakpathar Barrage is a concrete barrage across the Yamuna River adjacent to Dakpathar in Uttarakhand, India. In a run-of-the-river scheme, the barrage serves to divert water into the East Yamuna Canal for hydroelectric power production at the Dhakrani and Dhalipur Power Plants. The foundation stone for the dam was laid on 23 May 1949 by India's Prime Minister Jawaharlal Nehru. The barrage is controlled by 25 floodgates and has a length of 516.5 m (1,695 ft).
The Dharasu Power Station is a run-of-the-river hydroelectric power station on the Bhagirathi River located at Dharasu in Uttarkashi district, Uttarakhand, India. The power station was commissioned in 2008 and has a 304 MW capacity.
The Ramganga Dam, also known as the Kalagarh Dam, is an embankment dam on the Ramganga River 3 km (2 mi) upstream of Kalagarh in Pauri Garhwal district, Uttarakhand, India. It is located within the Jim Corbett National Park.
The Maneri Dam is a concrete gravity dam on the Bhagirathi River located at Maneri, 8.5 kilometres (5.3 mi) east of Uttarkashi in Uttarkashi district, Uttarakhand, India. The primary purpose of the dam is to divert water into a tunnel which feeds the 90 megawatts (120,000 hp) run-of-the-river Tiloth Power Plant.
As of 2018, hydroelectric power stations in the United Kingdom accounted for 1.87 GW of installed electrical generating capacity, being 2.2% of the UK's total generating capacity and 4.2% of UK's renewable energy generating capacity. This includes four conventional hydroelectric power stations and run-of-river schemes for which annual electricity production is approximately 5,000 GWh, being about 1.3% of the UK's total electricity production. There are also four pumped-storage hydroelectric power stations providing a further 2.8 GW of installed electrical generating capacity, and contributing up to 4,075 GWh of peak demand electricity annually.
The Broadlands Dam is a 35 MW run-of-the-river hydroelectric complex currently under construction in Kitulgala, Sri Lanka. The project is expected to be completed in 2020, and will consist of two dams, and a power station downstream.
SJVN, formerly known as Satluj Jal Vidyut Nigam, is an Indian public sector undertaking involved in hydroelectric power generation and transmission. It was incorporated in 1988 as Nathpa Jhakri Power Corporation, a joint venture between the Government of India and the Government of Himachal Pradesh. The company has a total operating hydropower capacity of 1912 MW through its two hydropower plants—Nathpa Jhakri and Rampur. In addition, it has an installed capacity of 97.6 MW of wind power and 81.9 MW of solar power.
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