:Kannagawa Hydropower Plant
{{Short description|Dam in Nagano and Gunma Prefectures, Japan}}
{{Infobox dam
| name = Kannagawa Hydropower Plant
| image = Minamiaiki Dam.jpg
| image_caption = The upper Minamiaiki Dam
| country = Japan
| location = Nagano Prefecture and Gunma Prefecture
| coordinates = {{coord|36|00|18|N|138|39|09|E|region:JP_type:landmark|display=inline,title}}
| owner = Tokyo Electric Power Company
| status = In partial operation
| res_name = Minamiaiki Reservoir
| res_capacity_total = {{Convert|19170000|m3|acre.ft|abbr=on}}
| lower_res_name = Ueno Reservoir
| lower_res_capacity_total = {{Convert|18400000|m3|acre.ft|abbr=on}}
| plant_pumpgenerators = Francis pump turbine
Operational: 2 x 470 MW
Under constr.: 4 x 470 MW
| plant_hydraulic_head = {{Convert|653|m|ft|abbr=on}}
| plant_capacity = {{convert|2820|MW|abbr=on}}
| opening = Unit 1: 2005
Unit 2: 2012
Units 3-6: 2032{{cite web | url=http://www.tepco.co.jp/en/press/corp-com/release/2012/1205253_1870.html | title=Operational Commencement of Unit 2, Kannagawa Hydroelectric Power Station | publisher=TEPCO | date=7 June 2012 | accessdate=22 May 2021}}{{cite web | url=http://www.tepco.co.jp/en/press/corp-com/release/betu12_e/images/120607e0301.pdf | title=Kannagawa Hydroelectric Power Station | publisher=TEPCO | date=7 June 2012 | accessdate=22 May 2021}}
| demolished =
}}
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 {{convert|470|MW}} pump-generators for a total installed capacity of {{convert|2820|MW}}. Unit 1 commenced commercial operation in 2005 and Unit 2 in 2012.[http://www.hydroworld.com/articles/2012/06/unit-2-online-at-japan.html HydroWorld: Unit 2 online at Japan's Kannagawa pumped-storage plant] When completed, the plant will have the third-largest (after Fengning Pumped Storage Power Station and Bath County Pumped Storage Station) pumped-storage power capacity in the world.
Construction
In July 1993, the Kannagawa Hydropower Field Survey Office was initiated and in July 1995, the power plant was approved by the Electric Power Development Coordination Council. In May 1997, construction on the project began and by October 2003, the area behind the Ueno Dam was being inundated with water and the next year, the Minamiaiki Dam's reservoir began to fill as well.{{cite web|title=Press Release: Commencement of Commercial Operation of Unit 1 of Kannagawa Hydropower Plant-- Pumped-Storage Power Plant with World's Largest Capacity|url=http://www.tepco.co.jp/en/press/corp-com/release/05122201-e.html|publisher=TEPCO|accessdate=31 August 2010|date=Dec 22, 2005}} Both dams were completed and the upper reservoir was filled by 2004. The first generator was commissioned on 22 December 2005 and the second on 7 June 2012. The remaining units 3-6 are scheduled for commissioning by 2032.
Power station
The power station is {{Convert|1600|ft}} underground and measures {{Convert|708|ft|m|abbr=on}} long, {{Convert|108|ft}} wide, and {{Convert|169|ft}} high. It will contain 6 x 470 MW pump generators for a total capacity of 2,820 MW. Water from the upper Minamiaiki Reservoir is transferred through the power house and after producing electricity, it runs to the lower Ueno Reservoir. The pump-generators can then pump water from the lower reservoir back up to the upper reservoir for re-use in hydroelectric power production. The water tunnel connecting the two reservoirs is {{Convert|3.8|mi}} long.{{cite web|last=Peltier|first=Robert|title=Kannagawa Hydropower Plant, Japan|url=http://www.powermag.com/issues/cover_stories/Kannagawa-Hydropower-Plant-Japan_461.html|publisher=Power Magazine|accessdate=31 August 2010|date=August 15, 2006|archive-date=10 March 2010|archive-url=https://web.archive.org/web/20100310133204/http://www.powermag.com/issues/cover_stories/Kannagawa-Hydropower-Plant-Japan_461.html|url-status=dead}} The power station also has an effective hydraulic head of {{Convert|653|m}} and maximum discharge of {{Convert|510|m3/s|ft3/s}}.{{cite web|title=Specifications of Kannagawa Pumped Storage Power Plant|url=http://www.ieahydro.org/04-Minamiaiki-Dam-upper-lge.htm|publisher=IEAHydro|accessdate=31 August 2010|url-status=dead|archiveurl=https://web.archive.org/web/20100727101459/http://www.ieahydro.org/04-Minamiaiki-Dam-upper-lge.htm|archivedate=27 July 2010}}
Dams
The Minamiaiki Dam is located in Nagano Prefecture and is a {{Convert|136|m}} high and {{Convert|444|m}} long rock-fill dam. It is made of {{Convert|7300000|m3|cuyd}} of material and withholds a {{Convert|19170000|m3|ft3|abbr=on}} reservoir. The Ueno Dam, in Gunma Prefecture, is a {{Convert|120|m}} high and {{Convert|350|m}} long concrete-gravity dam. It is made of {{Convert|720000|m3|cuyd}} of material and withholds a {{Convert|18400000|m3|ft3|abbr=on}} reservoir.
See also
{{stack|{{Portal|Japan|Water|Renewable energy}}}}