The Helms Pumped Storage Plant is located 50 mi (80 km) east of

Fresno, California Fresno () is a major city in the San Joaquin Valley of California, United States. It is the county seat of Fresno County and the largest city in the greater Central Valley region. It covers about and had a population of 542,107 in 2020, makin ...

in the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

Mountain Range's

Sierra National Forest Sierra National Forest is a U.S. national forest located on the western slope of central Sierra Nevada in Central California and bounded on the northwest by Yosemite National Park and the south by Kings Canyon National Park. The forest is kno ...

. It is a power station that uses Helms Creek canyon on the North Fork of the Kings River for off-river water storage and the

pumped-storage Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential ...

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 Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, or maximum effect, is the intended full-load sustained output of a facility such as a power station,

of 1,212 MW and is owned by

Pacific Gas and Electric Company The Pacific Gas and Electric Company (PG&E) is an American investor-owned utility (IOU). The company is headquartered in the Pacific Gas & Electric Building, in San Francisco, California. PG&E provides natural gas and electricity to 5.2 milli ...

Design and operation

The power plant operates by moving water between an upper and lower reservoir. When energy demand is high, water is released from the upper reservoir to the generating plant and the water is discharged into the lower reservoir. When demand is low (such as at night), water is pumped into the upper reservoir to be used as stored energy at a later time. This is accomplished by pump-generators which serve a dual role: the pumps can reverse for use as 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 than generating electricity but pumping occurs during periods of low demand with unused surplus energy available at lower costs from the electric grid. The upper reservoir, Courtright Reservoir, has a storage capacity of is at altitude of .

Wishon Reservoir Wishon Dam (National ID # CA00411) is a dam in Fresno County, California in the Sierra National Forest, in the Sierra Nevada Mountain Range. It impounds the North Fork Kings River to form Wishon Reservoir. The earthen and rockfill gravity dam was ...

, the lower reservoir, has a storage capacity of . It is at an altitude of . Connecting the reservoirs, from upper to lower, is first a long head-race tunnel which turns into a long steel

penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills. H ...

which drops in elevation and splits into three individual penstocks, which each feed a separate pump-generator. After the water has passed through the generating turbines, it is discharged into the lower reservoir via a long tail-race tunnel. The difference in elevation between the reservoirs has an effective

hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...

(drop of the water) of . The

underground power station An underground power station is a type of hydroelectric power station constructed by excavating the major components (e.g. machine hall, penstocks, and tailrace) from rock, rather than the more common surface-based construction methods. One or mor ...

is near Wishon Reservoir and houses three 404 MW

Francis pump turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proces ...

-generators. The Helms Pumped Storage project was designed to be used with the

Diablo Canyon Nuclear Power Plant The Diablo Canyon Power Plant is a nuclear power plant near Avila Beach in San Luis Obispo County, California. Since the permanent shutdown of the San Onofre Nuclear Generating Station in 2013, Diablo Canyon has been the only operational nucl ...

, also owned by PG&E, in the 1970s, when Diablo Canyon was being designed and permitted. It is connected to that power plant by a dedicated high-tension power line. "Diablo Canyon's odd cousin in the mountains"
October 12, 2015, San Luis Obispo Tribune

References

External links

Helms: Power from Water, Human Engineering
- PG&E video on the plant's operation {{Generating stations in California, state=autocollapse Energy infrastructure completed in 1984 Hydroelectric power plants in California Pumped-storage hydroelectric power stations in the United States Buildings and structures in Fresno County, California Sierra National Forest Pacific Gas and Electric Company Dams completed in 1984 Underground power stations 1984 establishments in California

Design and operation

See also

References

External links