“Water Battery” Being Considered on Mokelumne River

Earlier this year, GreenGenStorage received a renewal of their licensing period to submit Pre-Application Documents to the Federal Energy Regulatory Commission for their proposed Mokelumne Pumped Storage Water Battery Project. The developer hopes to submit their PAD by the end of the year for the project, which would utilize excess solar and wind energy to power their pumped storage technology, thereby generating electricity for the grid at peak energy-usage hours.

“During the midday peak of solar energy generation, we would pump water uphill to an upper reservoir,” Nicholas Sher, manager at GreenGenStorage said. “Then in the evening where energy usage is consumed the most, we would release that water downstream and it would drive a turbine, thus generating energy. Then by soaking up wind power in the evenings for release in the morning peak hours, we’re essentially just time-shifting renewable energy.”

By using renewable energy to transfer water back and forth between two reservoirs, the project would be a non-consumptive means of using water to generate power. In the case of the Mokelumne Pumped Storage Water Battery Project, the Salt Springs Reservoir has been identified as the lower reservoir, as it already has a small hydro-facility on it that generates about 44 megawatts of energy.

Two options are currently being explored for the upper reservoir that Salt Springs would be connected to via penstock pipes: the Lower Bear or Upper Bear Reservoir.