On Oct. 4, the Federal Energy Regulatory Commission went out for comment on a July 19 application from GreenGenStorage LLC for a preliminary permit under which it would study the feasibility of the Mokelumne Pumped Storage Project, to be located on the North Fork Mokelumne River, Bear River and Cole Creek in Amador and Calaveras counties, California.
The sole purpose of a preliminary permit, if issued, is to grant the permit holder priority to file a license application during the three-year permit term.
The project concept envisions the construction of a pumped storage generating facility consisting of: the existing Salt Springs Reservoir (part of Pacific Gas & Electric’s currently licensed Mokelumne River Project No. 137) as the lower pool; an upper reservoir using either the existing Upper Bear or Lower Bear River reservoirs (also part of PG&E’s Mokelumne River Project); a 16,000-foot to 20,000-foot power tunnel connecting the upper reservoir, pump turbines, and the lower reservoir; an underground powerhouse containing the pump-turbines and motor-generators; and an approximately 3,000-foot-long transmission line.
GreenGenStorage states that based on preliminary analyses, the project would have from one to three 380-MW generating units and an average annual electricity production of between 523 and 742 gigawatt-hours. GreenGenStorage plans to conduct studies to help further refine the range of suitable generation capabilities and other project characteristics. Noted the application: “At the present time, several different options are possible regarding size of generating units ranging from a 1-unit, 380-MW facility to a 3-unit, 1140-MW facility (3 units x 380-MW each unit) with existing reservoirs currently sufficient to provide approximately eight to ten hours of continuous output.”
The applicant contact is: Edward Cooper, Managing Director and Project Manager, GreenGenStorage LLC, PO Box 537, Summerland, CA 93067, (805) 450-2867, [email protected]
The deadline for filing comments, motions to intervene, competing applications (without notices of intent), or notices of intent to file competing applications is 60 days from the issuance of this Oct. 4 notice.
The location, number of circuits, voltage, and configuration of the project’s interconnection with the regional electric utility network would need to be established as part of the studies to be carried out during the permit term, the application noted. However, the project would probably interconnect at PG&E’s existing Salt Springs Powerhouse switchyard substation located uphill of the Salt Springs Powerhouse, just below Salt Springs dam. If the Salt Springs Powerhouse switchyard and substation is a feasible interconnection point, the project transmission line length will be approximately 3,000 feet. The interconnection voltage may be 230 or 500 kV, depending upon the results of studies to be carried out. The project transmission line may be one or two circuits, depending upon the results of studies to be carried out.
The project is proposed to store excess renewable energy, helping to integrate renewables onto the grid, and to supply firm peaking capacity with primary load-following capability. Assuming a 15 percent plant factor, typical for pumped storage projects, the average annual electricity production would be between 523 and 742 GWh. Assuming a cycle efficiency of 78 percent, typical for pumped storage, the pumping energy requirement would be between 670 and 951 GWh.
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