Helms Pumped Storage Plant

Helms Pumped Storage Plant
File:Courtright Reservoir 2.jpg Courtright, the upper reservoir
Location of Helms Pumped Storage Plant in California
Country	United States
Location	Fresno County
Coordinates
Status	Operational
Construction began	1977
Commission date	1984
Owner(s)	Pacific Gas and Electric Company
Pumped-storage power station
Upper reservoir	Courtright Reservoir
Upper res. capacity	123,000 acre·ft (151,718,266 m3)
Lower reservoir	Wishon Reservoir
Lower res. capacity	129,000 acre·ft (159,119,157 m3)
Hydraulic head	1,625 ft (495 m)
Generating units	3 x 404 MW Francis pump turbines
Power generation
Nameplate capacity	1,212 MW

The Helms Pumped Storage Plant is located 50 mi (80 km) east of Fresno, California in the Sierra Nevada Mountain Range's Sierra National Forest. It is a power station that uses Helms Creek canyon for off-river water storage and the pumped-storage hydroelectric method to generate electricity. After being planned in the early 1970s, construction on the plant began in June 1977 and commercial operations began on 30 June 1984. It has an installed capacity of 1,212 MW and is owned by Pacific Gas and Electric Company.

Design and operation

The power plant operates by moving water between two reservoirs, an upper and a lower. When energy demand is high, water is released from the upper reservoir to the plant where electricity is generated before the water is discharged into the lower reservoir. When demand is low at times such as night, water is then pumped back up to the upper reservoir to be used as stored energy for a later time. This is accomplished by pump-generators which serve a dual role as both pumps which can reverse into generators. The plant can go from a stand still to operational in eight minutes which allows it to meet peak energy demand. It consumes more electricity pumping versus generating electricity but pumping occurs during periods of low demand, making the plant economical.

The upper reservoir is known as Courtright Reservoir and it has a storage capacity of 123,000 acre·ft (151,718,266 m³) while sitting at an altitude of 8,184 ft (2,494 m). Wishon Reservoir serves as the lower reservoir and has a storage capacity of 129,000 acre·ft (159,119,157 m³). It is at an altitude of 6,550 ft (1,996 m). Connecting the reservoirs, in order from upper to lower, is first a 10,511 ft (3,204 m) long head-race tunnel which turns into a 2,248 ft (685 m) long steel penstock which drops in elevation and trifurcates into three individual penstocks which feed a separate pump-generator. After the water is used to generate electricity, it is discharged into the lower reservoir via a 3,797 ft (1,157 m) long tail-race tunnel. The difference in elevation between the reservoirs affords an effective hydraulic head (drop of the water) of 1,625 ft (495 m). The power plant is located underground near Wishon Reservoir and houses three 404 MW Francis pump turbine-generators.

See also

• List of pumped-storage hydroelectric power stations

External links

• Helms: Power from Water, Human Engineering - PG&E video on the plant's operationno:Helms vannkraftverk