Alta Mesa Pumped Storage

The Pumped Storage project is a 70 megawatt energy storage facility to be constructed in the San Gorgonio Pass near Palm Springs, California. The project will store electric power by pumping water uphill. Later, when power demand peaks, the stored water flows downhill to produce power. The Pumped Storage facility will provide the ability to store power produced by nearby wind power projects to allow for "firm" power sales from an intermittent resource.

Major project facilities will consist of an upper reservoir atop the Alta Mesa, a lower reservoir near the valley floor, a powerhouse with a reversible pump/turbine, and a pipeline connecting the reservoirs with the powerhouse. No natural watercourses will be used by the project; it will be a closed-loop, constructed system. The facility will be able to store 420 megawatt-hours (about the daily consumption of 17,500 homes) and produce its full 70 megawatt rated output for 6 continuous hours.

Other features of the project include:

  • Will produce 130,000 MWh per year of high-value on-peak power, and consume 175,000 MWh per year of low-value off-peak power.
  • Cycle efficiency of 74%.
  • 1250 feet vertical separation between upper and lower reservoirs.
    6,300 feet of penstock length.
  • Approx. 96 inch penstock diameter.
    113 million gallons of water storage.
  • Interconnect with Southern California Edison (and then to the California Independent System Operator grid).
  • Environmental review and permitting underway.
    Project site owned by TenderLand Power Company affiliate.

A pump turbine used at another project

Detail of preliminary design near lower reservoir and powerhouse

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