Pacific Gas & Electric (PG&E) has commissioned a feasibility study for a major new pumped storage facility in Amador County, California. The facility would be used to provide a backup system for the power grid, in the case of large fluctuations of electricity production from wind and solar energy facilities. The intermittency of wind and solar as energy sources causes major issues for power grid operators, who constantly have to be prepared to compensate for sudden drops or peaks in electricity supply from these sources, in order to keep the grid stable. Pumped storage is one of the best solutions for storing energy for later use.

Basically, the concept boils down to using excess power to pump water into higher altitude reservoirs (natural or manmade lakes), and then have that stored potential available in case of need, which is then supplied to a hydropower station, to generate electricity. These facilities can be built to work separately, or as is often the case, housed in a single facility using a pump/turbine machine for the job (reversible hydropower plants).

The feasibility study is looking into the possibility of developing a pumped storage potential between 400 and 1200 MW. If the feasibility study returns a positive assessment, the facility should be completed and available by 2020.

[source: Next100 (PG&E)]