Hydroelectric Generators

What are so-called ‘water batteries’?

Answer: Secondary reservoirs that supplement other renewable energy sources.

October 17, 2022 • Government Technology News Staff

One of solar energy’s biggest drawbacks is that we only get it when the sun is up, unless we have ways to store what we don’t use to tap into when the sun goes down. One way to do this is to turn water into batteries … of sorts.

The San Diego County Water Authority has proposed a project that would use the San Vicente Reservoir to make these water batteries. By building a smaller upper reservoir connected to the main one, the city of San Diego would be able to store 4,000 megawatts of energy per day. That’s enough to light up 135,000 homes when it gets dark and there’s no more solar power to draw on.

“During off-peak periods — when power is inexpensive and renewable supplies from wind and solar facilities exceed demand — turbines will pump water to the upper reservoir where it will act as a battery of stored potential energy,” according to the authority’s website. Then when the energy is needed, it will be discharged to flow downhill, through turbines, and back into the main reservoir, meaning no water will be wasted in the process.