| Shin-Takasegawa Pumped Storage Station | |
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The Takase Dam |
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| Country | Japan |
| Location | Ōmachi |
| Coordinates | |
| Status | Operational |
| Construction began | 1971 |
| Commission date | 1979 |
| Owner(s) | TEPCO |
| Reservoir information | |
| Upper reservoir | Takase Reservoir |
| Reservoir capacity | 76,200,000 m3 (61,776 acre·ft) |
| Lower reservoir | Nankura Reservoir |
| Reservoir capacity | 32,500,000 m3 (26,348 acre·ft) |
| Pumped-storage station information | |
| Penstocks | 2 |
| Generating units | 4 x 320 MW reversible Francis-type |
| Hydraulic head | 229 m (751 ft) (net) |
| Power generation information | |
| Installed capacity | 1,280 MW |
The Shin-Takasegawa Pumped Storage Station uses the Takase River to operate a pumped storage hydroelectric scheme about 12 km (7 mi) west of Ōmachi in Nagano Prefecture, Japan. Construction on the complex began in 1971, concluded in 1978 and the power station was commissioned in 1979. The power plant has a 1,280 MW installed capacity and its upper reservoir is created by the Takase Dam, a rock-fill dam — which at 176 m (577 ft) in height is the tallest of its type in Japan.[1] It is also the second tallest dam in Japan, next to Kurobe Dam.[2]
Contents |
Creating the upper reservoir is the Takase Dam which is a 176 m (577 ft) tall and 362 m (1,188 ft) long rock-fill embankment dam with a structural volume of 11,586,000 m3 (15,153,916 cu yd). The Takase Reservoir has a 76,200,000 m3 (61,776 acre·ft) capacity of which only 16,200,000 m3 (13,134 acre·ft) is active (or "useful") for power generation. The low active capacity of the reservoir is due to the high levels of silt in the Takase River which cause the reservoir to reserve 79 percent of its capacity for this purpose. During operation, the upper reservoir only draws down 10 m (33 ft).[1]
During periods of high energy demand, water from the Takase Reservoir is released down to the power station. After received by the intake, water initially travels along two 8 m (26 ft) diameter and 2,600 m (8,530 ft) long head-race tunnels. At the terminus of these tunnels, they split into four 330 m (1,083 ft) long penstocks which drop down a 200 m (656 ft) deep shaft to the underground power station. At the power station, the water operates four 320 MW reversible Francis turbine-generators before being discharged into the lower reservoir, created by the Nanakura Dam. When energy demand is low and therefore electricity less expensive, the turbines reverse and pump water from the lower reservoir back into the upper reservoir. This process repeats depending upon energy demand and water availability. Water released from the lower reservoir is used to power the Nakanosawa Power Station which uses 140.8 m (462 ft) of hydraulic head to power a single 42 MW Francis turbine generator.[1] It was commissioned in May 1980.[3]
The Nanakura Dam is a 125 m (410 ft) tall and 340 m (1,115 ft) long rock-fill embankment dam with a structural volume of 7,380,000 m3 (9,652,676 cu yd). The reservoir created by the dam, the lower reservoir, has a 32,500,000 m3 (26,348 acre·ft) capacity of which 16,200,000 m3 (13,134 acre·ft) is active. To protect in against rapid draw-down in water levels (as much as 28 m (92 ft)), the top of the dam is coated in hard rock materials.[1]
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