Renewable energy is without doubt the future, but as much as it is necessary, there is one big obstacle that needs to be overcome – its storage. Solar panels cannot produce electricity without sun, nor can wind turbines without wind, while, on the other hand, there can be excesses of electricity during heat waves or storms.
The solution comes in the form of batteries. When there is surplus energy, it gets stored and when natural elements are lacking, the battery release the accumulated energy. However, the type of batteries we know are not a viable option, one of the main problems being their cost.
1. Water batteries
Hydropower brings the solution. Water batteries, unlike traditional hydropower plants, do not use a river’s flow to generate electricity. Instead, they rely on two lakes, or reservoirs, at different altitudes, and a system of pumps. When there is a surplus of electricity in the grid, it is used to pump water from the lake at a lower altitude to the one at a higher altitude. When there is a lack of power, water is let back to the lower reservoir, passing through turbines that generate electricity.
2. San Vicente Energy Storage Facility
One such water battery has been inaugurated in Switzerland this year and now the San Diego County, in California, is building a similar project. The San Vicente Energy Storage Facility is under consideration by a partnership of the San Diego County Water Authority and the City of San Diego.
When completed, in 10 years, the project will have the potential to store 4,000 Megawatt-hours per day of energy (500 Megawatts of capacity for eight hours), which is enough energy to power about 135,000 homes.
A small upper reservoir will be created above the San Vicente Reservoir, along with a tunnel system and an underground powerhouse to connect the two. The powerhouse is proposed to contain four reversible pump turbines. 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. During high energy use, the system will discharge energy as water from the upper reservoir flows downhill through the turbines.
We have a problem if we’re going to have these continuous heat waves. We need a facility to store energy so that we don’t need to turn off our appliances.
Neena Kuzmich, Deputy Director of Engineering for the water authority
This past summer, during a heat wave, there was so much power generated by solar plants that grid operators had to turn away more than 2,000 megawatt hours of electricity. It was wasted because there was no possibility of storing it. Later on the same day, residents were asked to turn off their appliances, as the sun was going down and the grid was undersupplied.
In July 2021, San Vicente Energy Storage Facility received $18 million from the state budget, enough to advance the project through initial design, environmental reviews and the federal licensing process. The City of San Diego and the Water Authority are currently negotiating a project development agreement with the BHE Kiewit Team to develop Phase 1 of the potential San Vicente Energy Storage Facility Project.
