Bath County Pumped Storage Station
The Bath County Pumped Storage Station is a pumped storage hydroelectric power plant, which is described as the "largest battery in the world", with a maximum generation capacity of 3,003 MW, an average of 2,772 MW, and a total storage capacity of 24,000 MWh. The station is located in the northern corner of Bath County, Virginia, on the southeast side of the Eastern Continental Divide, which forms this section of the border between Virginia and West Virginia. The station consists of two reservoirs separated by about  in elevation. It was the largest pumped-storage power station in the world until 2021, when it was surpassed by the Fengning Pumped Storage Power Station.

Construction on the power station, with an original capacity of , began in March 1977 and was completed in December 1985 at a cost of $1.6 billion, Voith-Siemens upgraded the six turbines between 2004 and 2009, increasing power generation to 500.5 MW and pumping power to  for each turbine. Bath County Station is jointly owned by Dominion Generation (60%) and FirstEnergy (40%), and managed by Dominion. It stores energy for PJM Interconnection, a regional transmission organization in 13 states and the District of Columbia.

Design
The upper and lower reservoirs are created by earth and rock-filled embankment dams. The upper reservoir dam is  high,  long and has a structural volume of . The upper reservoir on Little Back Creek has a surface area of  and storage capacity of . The lower reservoir dam on Back Creek is  high and  in length. It has a structural volume of  and creates a reservoir with a surface area of  and storage capacity of . Connecting the upper reservoir to the power station are three water conduits between  long. The conduits each lead to a  shaft which bifurcates into two penstocks (for a total of six) before reaching the turbines. Each penstock is  in diameter and between  in length. Maximum static pressure from the top of the water delivery system to the turbines is .

Method of operation 
Water is released from the upper reservoir during periods of high demand and is used to generate electricity.  What makes this different from other hydroelectric dams is that during times of low demand, power is taken from coal, nuclear, and other power plants and is used to pump water from the lower to the upper reservoir. Although this plant uses more power than it generates, it allows these other plants to operate at close to peak efficiency for an overall cost savings. Back Creek and Little Back Creek, the water sources used to create the reservoirs, have a relatively small flow rate. However, since water is pumped between the reservoirs equally, the only water taken from these creeks now that the reservoirs are full is to replace the water lost to evaporation. During operation, the water level fluctuates by over  in the upper reservoir and  feet in the lower reservoir.

When generating power, the water flow can be as much as  per minute (850 m3/s). When storing power, the flow can be as much as  per minute (800 m3/s).

Environment
A fishing habitat was created downstream of the facility.
In times of drought water quality can be maintained by using nearby recreational reservoirs to supply extra water to the creeks. The creeks and recreational reservoirs have water quality sufficient for fish.

See also 

 List of energy storage projects
 Pumped-storage hydroelectricity
 List of largest hydroelectric power stations in the United States

References

External links 
 Dominion Resources
FirstEnergy
 Bath County Pumped Storage Station Home Page

Energy infrastructure completed in 1985
Buildings and structures in Bath County, Virginia
Hydroelectric power plants in Virginia
Pumped-storage hydroelectric power stations in the United States
Dams in Virginia
1985 establishments in Virginia
Earth-filled dams
Rock-filled dams
Dams completed in 1985