To understand a sharp-elbows squabble thatâs developing behind the scenes in the state Capitol, one must first understand âpumped-storage hydro,â a way for electrical energy to be stored. In its simplest form, water stored in a reservoir is released to generate power as it flows into a second reservoir at a lower elevation. Later, when the electrical gridâs need for power diminishes, the water is pumped back into the upper reservoir so the cycle can be repeated when demand increases. Itâs not a new technology; in fact itâs been around for more than a century although never more than a marginal factor in global power generation. However, itâs drawing more interest of late in California because the state is pushing hard, in the name of battling climate change, to eliminate natural gas-fired generation in favor of wind, solar and other sources that do not emit greenhouse gases.