Pumped Up: Renewables Growth Revives Old Energy-Storage Method

Moving water uphill lets producers of solar and wind power bank energy for use when it is needed most.

Forget about Tesla Motors Inc.’s batteries: The hottest way to store energy in the electricity business today is a century-old technology that involves moving water to stash power.

Known as pumped storage, the giant facilities push large volumes of water uphill when there is surplus electricity, and then let gravity move it back down through turbines to generate hydroelectric power when extra kilowatts are needed.

Newer technologies for energy storage—including batteries, flywheels, compressed air and ice—are under development, but the proven, old-school solution of storing water as a proxy for power is attracting renewed respect from utilities and environmentalists aiming to fight climate change. It helps solve a big problem as power companies invest in renewable energy, which doesn’t always produce electricity when it is most needed.

California, for example, set a record for solar-power production in early July. But peak demand for electricity comes in the early evening, long after solar production has peaked. Pumped storage gives producers a way to bank energy for future use.

full article on wsj.com