As part of this effort, the Water Authority and the City of San Diego have issued a joint request for letters of interest to reach out  to electric utilities, developers, investors and energy off-takers to help determine who may be interested in participating in the potential project.

The project could provide electric grid stability in the region during peak times or at times when electricity demand is high and renewable energy supplies are limited.

Capable of providing 8 hours of storage capacity daily, the project could help ease pressure on electric grids that are  increasingly dependent on renewable energy.

The Water Authority board of directors chair Mark Muir said: “When we filled San Vicente Reservoir last summer, we filled it with more than just water – we filled it with huge potential for energy benefits.

“Given this new potential for energy from a recently expanded water resource, it’s only prudent to continue to research the potential benefits to our region’s ratepayers.”

The proposed project would comprise an interconnection and pumping system between the existing San Vicente Reservoir and a new, smaller reservoir located uphill.

During off-peak energy-use periods, the pumping system would be used to pump water from the existing San Vicente Reservoir to the new upper reservoir.

The process will create a bank of stored hydroelectric energy in the upper reservoir which would be released to the lower reservoir by gravity when energy demand and electricity costs are high and when other renewable energy supplies are not available.