Colorado River

Water batteries could soon power 130,000 homes in San Diego at night time

The project is called pumped hydro energy storage.

Loukia Papadopoulos
Created: Oct 14, 2022 08:13 AM EST

The San Diego County Water Authority is planning to use its San Vicente Reservoir to store solar power making clean energy in the region viable, according to an article by NPR published on Friday.

Powering 130,000 homes

The project will take ten years to be built and will see large underground pipes connect San Vicente’s lake to a new reservoir about 1100 feet higher. California’s solar power will pump water into that upper reservoir, storing electricity.

At night, when solar power is unavailable, operators would open a valve releasing the force of 8 million tons of water and driving turbines capable of generating 500 megawatts of electricity for up to eight hours, enough to power 130,000 homes.

“It’s a water battery!” Neena Kuzmich, Deputy Director of Engineering for the water authority, told NPR. A type of battery that is set to be more common as energy systems switch to renewables.

During the day, especially in heat waves, California has so much solar power available that the grid can’t take it all. During the last heat wave, grid operators turned away more than 2000 megawatt hours of electricity. This was wasted electricity that could not be stored for night use where it was needed most.

“We have a problem if we’re going to have these continuous heat waves,” Kuzmich says. “We need a facility to store energy so that we don’t need to turn off our appliances.”

The technology that San Diego wants to install is called pumped hydro energy storage, and a few of these have been built over the past 30 years in the US. Now, there is renewed interest in them.

“Just in the past several years, 92 new projects have come into the development pipeline,” told NPR Malcolm Woolf, president, and CEO of the National Hydropower Association. However, most of them are just in the planning stages.

Qualifying for tax credits

Luckily, the climate bill President Biden signed in August ensures they now qualify for the same 30 percent tax credit from which solar and wind projects benefit. “That is an absolute game-changer,” Woolf says. “A number of these projects that have been in the pipeline for a number of years now suddenly are a whole lot more bankable.”

Even better, the technology has evolved to be more efficient and less disturbing to the natural environment in which it is built. Woolf says pumped hydro facilities don’t have to be as massive as those of the past century and don’t need to disturb free-flowing streams and rivers.

Even Kelly Catlett, director of hydropower reform at American Rivers, an environmental advocacy organization that has in the past warned about the environmental harm caused by dams, says that “there are good pumped storage projects” and that San Diego’s looks like one of them.

Catlett says, “Looks like something that we could potentially support. I’m unaware of any opposition by indigenous nations, which is another really important factor, as they have borne a lot of the impacts of hydropower development over the decades.”

Does that mean that San Diego will soon benefit from stored renewable energy? One can only hope!