Pumped Storage

A Water-Based Battery

Pumped hydroelectric storage facilities store energy in the form of water in an upper reservoir, pumped from a reservoir at a lower elevation. During periods of high electricity demand, power is generated by releasing the stored water through turbines in the same manner as a conventional hydropower station. During periods of low demand (usually nights or weekends when electricity is also lower cost), the upper reservoir is recharged by using lower-cost electricity from the grid to pump the water back to the upper reservoir. Invented the 1920’s, pumped storage technology remains one of the most efficient large-scale forms of “renewable” energy storage boasting round trip efficiency of up to 87 percent and a lifespan up to 100 years. Further, pump and storage facilities improve electricity supply reliability without the environmental impacts of coal, oil and gas, or nuclear fueled electricity generation.

This efficient, clean energy source allows “instant-on” power generation when consumer need spikes, or when renewable sources such as solar and wind energy are not available (such as cloudy, windless days or at night).

Pumped storage requires significant difference in elevation between the source lake and the upper reservoir for maximum efficiency.  This means sites must be chosen carefully.  The proposed Lake Elsinore site has been identified for many years as uniquely suited for pump storage and will enable optimized renewable energy generation in California, in accordance with the State’s renewables and environmental objectives.