The potential project would consist of a closed-loop interconnection and pumping system between the existing San Vicente Reservoir (which is owned by the City of San Diego) near Lakeside and a new, smaller reservoir located uphill. The system could provide up to 500 megawatts of renewable energy. It would be used during off-peak energy-use periods, pumping water uphill to the new upper reservoir to create a bank of stored hydroelectric energy. That energy would be released to the lower reservoir by gravity at times when other renewable energy supplies, such as solar, are unavailable and when energy demand and electricity costs are higher.

In addition to potentially adding renewable energy to the region, energy storage could support electrical grid operations that are essential to integrating large new supplies of other renewable electricity into the California and western power grids -- notably solar, but also wind. It also would make it easier to quickly increase or decrease energy generation as needed.