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.
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.
Ueno is a village located in Gunma Prefecture, Japan. As of 1 October 2020, the village had an estimated population of 1,149 in 571 households, and a population density of 6.3 persons per km2. The total area of the village is 181.85 square kilometres (70.21 sq mi). The village has the lowest population density of any municipality in Japan.
Minakami is a town located in Gunma Prefecture, Japan. As of 31 October 2020, the town had an estimated population of 18,383 in 7938 households, and a population density of 24 persons per km2. The total area of the town is 781.08 square kilometres (301.58 sq mi). Much of the town is within the borders of Jōshin'etsu-kōgen National Park.
The Tenryū River is a river in central Honshū, Japan. With a length of 213 km (132 mi), it is Japan's ninth longest river.
The Tokuyama Dam is an embankment dam near Ibigawa, Ibi District, Gifu Prefecture in Japan. The dam was completed in 2008 and will support a 153 MW hydroelectric power station that is expected to be fully operational in 2015. Currently, Unit 1 at 23 MW was commissioned in May 2014. The dam was originally intended to withhold the upper reservoir of a 400 MW pumped-storage power station until a design change in 2004. The dam is also intended for flood control and water supply. It is the largest dam by structural volume in Japan and withholds the country's largest reservoir by volume as well.
The Shō River has its source in Mount Eboshi in the Shōkawa-chō area of Takayama, Gifu Prefecture, Japan. After flowing for 115 km (71 mi) through the northern part of Gifu Prefecture and the western part of Toyama Prefecture, it empties into Toyama Bay.
The Agatsuma River is a major river in the northern Kantō region of Japan. It is 76.22 kilometres (47.36 mi) in length and has a basin area of 1,366 square kilometres (527 sq mi). Located entirely within Gunma Prefecture, it is one of the prefecture's major rivers. It is also a major tributary of the Tone River. The river is an important source of hydroelectric power, and 17 power plants are located on its banks.
The Sakuma Dam is a dam on the Tenryū River, located on the border of Toyone, Kitashitara District, Aichi Prefecture on the island of Honshū, Japan. It is one of the tallest dams in Japan and supports a 350 MW hydroelectric power station. Nearby a frequency converter station is installed, allowing interchange of power between Japan's 50 Hz and 60 Hz AC networks.
Naramata Dam is a dam near Minakami, in the Gunma Prefecture of Japan. It supports a 12.2 MW hydroelectric power station.
Nozori Dam (野反ダム) is a dam located in the town of Nakanojō, Agatsuma District, Gunma Prefecture, Japan. It is a hydroelectric dam operated by Tokyo Electric Power Company.The lake created by the dam is known as Lake Nozori.
Yagisawa Dam (矢木沢ダム) is a dam in the Gunma Prefecture of Japan; it supports a 240 MW hydroelectric power station.
Aimata Dam (相俣ダム) is a dam built on the Akaya River, part of the class-A Tonegawa River system at Aimata in the city of Minakami, in the Tone District of Gunma Prefecture, Japan.
Fujiwara Dam (藤原ダム) is a gravity dam on the Tone River in Gunma Prefecture of Japan. It is located 14 km (9 mi) north of Minakami. It was constructed between 1951 and 1957. The dam itself supports a single Francis turbine hydroelectric generator with a 23 MW capacity which was commissioned in 1957. The reservoir created by the dam serves as the lower reservoir for the 1,200 Tamahara Pumped Storage Power Station which was commissioned in 1986. The dam is 95 m (312 ft) high and withholds a reservoir with a 52,490,000 m3 (42,554 acre⋅ft) storage capacity.
Tanbara Dam is a rock-fill embankment dam impounding the headwaters of the Hotchi River, a Tone River tributary in Gunma Prefecture of Japan. It is located 14 kilometres (8.7 mi) north of Numata. It creates the upper reservoir for the 1,200 megawatts (1,600,000 hp) Tamahara Pumped Storage Power Station (玉原発電所). Construction began in 1973 and the dam was complete in 1981 while the power station was commissioned in 1986. It is 116 metres (381 ft) tall and withholds a reservoir with a storage capacity of 14,800,000 m3 (11,999 acre⋅ft). Of that capacity, 13,000,000 cubic metres (11,000 acre⋅ft) is active for power generation. The lower reservoir for the pumped-storage power station is created by the Fujiwara Dam, located 4 km (2 mi) to the northwest on another Tone River tributary. Power is generated during periods of high energy demand and pumping occurs during times when energy demand is low such as at night. The power station contains four 300 megawatts (400,000 hp) reversible Francis turbine pump-generators which serve to both pump water and generate electricity. The upper Tamahara Reservoir is at an elevation of 1,177 metres (3,862 ft) and the lower Fujiwara Reservoir is at 651 metres (2,136 ft) which affords the power station an effective hydraulic head of 518 metres (1,699 ft). When pumping, the pump-generators can move up to 210 cubic metres per second (7,400 cu ft/s) of water and when generating, they discharge up to 276 cubic metres per second (9,700 cu ft/s).
The Samanala Dam is a dam primarily used for hydroelectric power generation in Sri Lanka. Commissioned in 1992, the Samanalawewa Project is the third-largest hydroelectric scheme in the country, producing 405 GWh of energy annually. It was built with financial support from Japan and the United Kingdom. It is notable for a large leak on its right bank. Power production continues as planned despite the leakage, and the water from the leak now provides two thirds of the water issued by the reservoir for agriculture in downstream areas.
The Kannagawa Hydropower Plant (神流川発電所) is an under construction pumped-storage hydroelectric power plant near Minamiaiki in Nagano Prefecture and Ueno in Gunma Prefecture, Japan. The power plant utilizes the Minamiaiki River along with an upper and lower reservoir created by two dams, the upper Minamiaiki Dam and the lower Ueno Dam. The power station in between the two dams will contain six 470 megawatts (630,000 hp) pump-generators for a total installed capacity of 2,820 megawatts (3,780,000 hp). Unit 1 commenced commercial operation in 2005 and Unit 2 in 2012. When completed, the plant will have the second-largest pumped-storage power capacity in the world.
The Shin-Takasegawa Pumped Storage Station (新高瀬川発電所) uses the Takase River to operate a pumped storage hydroelectric scheme about 12 kilometres (7.5 mi) west of Ōmachi in Nagano Prefecture, Japan. Part of the system is within Chūbu-Sangaku National Park.
The Tadami River is a major tributary of the Agano River in Japan. Its basin covers 8,400 km2 (3,243 sq mi) and its main stem is extensively regulated and developed for hydroelectric power. The river is located within Niigata, Gunma and Fukushima Prefectures.
