Helms Pumped Storage Plant
|Helms Pumped Storage Plant|
Courtright, the upper reservoir
|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|
|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.
- The Dam Truth About Reservoirs "There are 2 broad categories of reservoirs, the valley reservoir [or on-river storage,] and the off-river storage reservoir"
- "By the Numbers: Helms Pumped Storage Facility". Pacific Gas and Electric Company. 17 October 2011. Retrieved 15 January 2012.
- Kermit Jr., Paul (March 1989). "Design Features of The Helms Pumped Storage Project". IEEE Transactions on Energy Conversion (Institute of Electrical and Electronics Engineers) 4 (1). Retrieved 15 January 2012.
- Yeung, Manho (17 October 2008). "Helms Pumped Storage Plant". Pacific Gas and Electric Compan. Retrieved 15 January 2012.
- Helms: Power from Water, Human Engineering - PG&E video on the plant's operation