:Shin-Takasegawa Pumped Storage Station

{{Infobox dam

| name = Shin-Takasegawa Pumped Storage Station

| name_official =

| image = Takase Dam 2008-10-13.jpg

| image_caption = The Takase Dam

| image_alt =

| coordinates = {{coord|36|28|26|N|137|41|23|E|type:landmark|display=inline,title}}

| country = Japan

| location = Ōmachi,
Nagano Prefecture

| status = O

| construction_began = 1971

| opening = 1980

| demolished =

| cost =

| owner = TEPCO

| operator =

| res_name = Takase Reservoir

| res_capacity_total = {{Convert|76200000|m3|acre.ft|abbr=on}}

| lower_res_name = Nankura Reservoir

| lower_res_capacity_total = {{Convert|32500000|m3|acre.ft|abbr=on}}

| plant_pumpgenerators =

| plant_turbines = 4 x {{convert|320|MW|abbr=on}} reversible Francis-type

| plant_pumps =

| plant_hydraulic_head = {{Convert|229|m|abbr=on}} (net)

| plant_capacity = {{convert|1280|MW|abbr=on}}

| plant_capacity_factor =

| website =

| extra =

}}

The Shin-Takasegawa Pumped Storage Station (新高瀬川発電所) uses the Takase River (a tributary of the Shinano River) to operate a pumped storage hydroelectric scheme about {{Convert|12|km}} west of Ōmachi in Nagano Prefecture, Japan. Part of the system is within Chūbu-Sangaku National Park.

Construction on the complex began in 1971, concluded in 1978 and the power station was commissioned in 1980. The power plant has a {{convert|1280|MW}} installed capacity and its upper reservoir is created by the Takase Dam, a rock-fill dam — which at {{Convert|176|m}} in height is the tallest of its type in Japan.{{cite book |last=Engineers |first=prepared by Task Committee on Pumped Storage of the Committee on Hydropower of the Energy Division of the American Society of Civil |title=Hydroelectric pumped storage technology : international experience |year=1996|publisher=American Soc. of Civil Engineers |location=New York, NY |isbn=0-7844-0144-6 |pages=2.5–1–2.5–4|url=https://books.google.com/books?id=iCSl-pxL7IwC&q=Shin+Takasegawa+Pumped+Storage+Station&pg=PA12}}

It is also the second tallest dam in Japan, next to Kurobe Dam.{{cite web|title=Takase Dam|url=http://damnet.or.jp/cgi-bin/binranA/All.cgi?db4=1027|publisher=Japan Dam Handbook|language=Japanese|accessdate=8 August 2011}}

Design and operation

File:Nanakura Dam.jpg

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 {{Convert|140.8|m}} of hydraulic head to power a single {{convert|42|MW}} Francis turbine generator. It was commissioned in May 1980.{{cite web|title=Tokyo Electric Power Plant Nakanosawa|url=http://www.suiryoku.com/gallery/nagano/nknosawa/nknosawa.html|publisher=Suiryoku.com|accessdate=8 August 2011|language=Japanese}}

=Takase Dam=

Creating the upper reservoir is the Takase Dam which is a {{Convert|176|m|adj=on}} tall and {{Convert|362|m|adj=on}} long rock-fill embankment dam with a structural volume of {{Convert|11586000|m3|cuyd}}. The Takase Reservoir has a {{Convert|76200000|m3|acre.ft}} capacity of which only {{Convert|16200000|m3|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 {{Convert|10|m}}.

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 {{Convert|8|m}} diameter and {{Convert|2600|m}} long head-race tunnels. At the terminus of these tunnels, they split into four {{Convert|330|m}} long penstocks which drop down a {{Convert|200|m}} deep shaft to the underground power station. At the power station, the water operates four {{convert|320|MW}} reversible Francis turbine-generators before being discharged into the lower reservoir, created by the Nanakura Dam.

=Nanakura Dam=

The Nanakura Dam is a {{Convert|125|m|adj=on}} tall and {{Convert|340|m|adj=on}} long rock-fill embankment dam with a structural volume of {{Convert|7380000|m3|cuyd}}. The reservoir created by the dam, the lower reservoir, has a {{Convert|32500000|m3|acre.ft}} capacity of which {{Convert|16200000|m3|acre.ft}} is active. To protect in against rapid draw-down in water levels (as much as {{Convert|28|m}}), the top of the dam is coated in hard rock materials.