Energy storage facilities, whether battery or pumped hydroelectric storage, perform the same function. They each take excess energy when it’s not needed and place it on the grid during periods of high demand.
Dominion Energy already operates the largest energy storage facility in the world. The Bath County Pumped Storage Station is nestled in the Allegheny Mountains in the picturesque highlands of Western Virginia. The facility began commercial operations in December 1985 and has a net generating capacity of 3,000 megawatts (MW). It can generate enough electricity to power approximately 750,000 homes. Or in data center terms, this facility can support the entire Virginia data center industry at its 2020 peak performance.
The Bath County Pumped Storage consists of two large reservoirs—one atop an embankment and the other 1,260 feet below. When demand is low, typically at night, water is pumped from the lower to the upper reservoir. Dominion Energy pulls in market power of the grid to pump the water for storage, and when demand is high, releases the water through six turbine generators as gravity drops it to the lower reservoir.
This overnight pumping and morning release of water occurs daily, allowing Dominion Energy to dispatch zero carbon generation first to support customer needs.
A closer look at the Bath County Pumped Storage Station:
- Three 28-foot diameter Power Tunnels connect the Upper Reservoir and the Lower Reservoir with the power house/pumping station at the Lower Reservoir.
- Each turbine generator has a capacity of 505MW.
- The electricity produced is dispatched into and removed from the Dominion Energy 500kV electric transmission grid for both generation and pumping.
- The pumped storage station is highly reliable with more than 4,000 generator starts annually to support system generation and reliability.