San Diego County authority pursues pumped storage project

The San Diego County Water Authority applied June 28 to the Federal Energy Regulatory Commission for a preliminary permit on the up to 500-MW San Vicente Pumped-Storage Water Power Project.

A preliminary permit allows a party to explore the feasibility of a project, with a later license application needed if the decision is to proceed with the project.

In September 2000, the governor of California signed Senate Bill 552 (SB552), which substantially granted the Water Authority new entitlement to enter the electric and natural gas wholesale markets. SB552 modified the County Water Authority Act to allow hydroelectric power generated by the Water Authority’s water delivery system to be sold to any retail electric provider. It also authorized the Water Authority to purchase federal power, construct, own, and operate electric power generation facilities to service its or its member agencies’ needs, and to purchase and transport natural gas.

In October 2000, the Water Authority filed a preliminary permit with FERC for the Olivenhain/Lake Hodges Pumped-Storage Project. This project is located in the vicinity of the northern end of the city of San Diego. The permit was approved by FERC in February 2001. The 40-MW Olivenhain-Hodges Pumped-Storage Project construction is complete and it is commercially operational.

The Water Authority was granted a preliminary permit in July 2010 for the San Vicente Pumped Storage Water Power Project that is scheduled to expire on June 30, 2013. During the prior permit period, the Water Authority efforts focused on constructing a new San Vicente Dam to increase the capacity of the San Vicente Reservoir. Under the preliminary permit, the Water Authority pursued all activities under the permit diligently and in good faith. Because the project is an ancillary part of the Water Authority’s Emergency Storage Project (ESP), the final details for the generating facilities, as well as any FERC hydroelectric development application, must await final details of the ESP.

The ESP is a system of reservoirs, interconnected pipelines and pumping stations designed to make water available to the San Diego region in the event of an interruption in imported water deliveries. The expanded San Vicente Reservoir, a component of the ESP, is envisioned as the lower reservoir for the pumped storage project.

The Water Authority and the city of San Diego entered into an agreement in 1998 for the joint use of an expanded San Vicente Dam and Reservoir as part of the ESP. Under this agreement, the Water Authority is responsible for the design and construction of the expanded San Vicente Dam and Reservoir, consisting of raising the dam by at least 54 feet, corresponding to an increased capacity of the reservoir by more than 52,000 acre-feet. Although contemplated primarily for the ESP, the 1998 agreement granted rights for the Water Authority to raise San Vicente Dam higher than planned for the ESP.

San Diego currently expanding existing reservoir

The Water Authority said it is presently expanding the San Vicente Reservoir, beyond the size projected for the ESP, as part of its Carryover Storage Project (CSP). The CSP aims to store water accumulated during wet seasons for use in subsequent dry seasons or in times of drought. A single raise of 117 feet of San Vicente Dam to expand the reservoir to meet both ESP and CSP needs is underway and construction is scheduled to be complete in winter 2013. Upon completion of construction to expand the dam and reservoir, the Water Authority will own the water storage rights to the additional combined ESP/CSP storage capacity of 152,000 acre-feet.

The lower reservoir’s environmental, permitting, and design are complete, and the construction is nearing completion. Therefore, the Water Authority now seeks a preliminary permit for the project so that it may: complete construction of the lower reservoir; continue with the economic and financial studies, environmental and engineering studies focused on the upper reservoir; and secure and maintain priority of application for a license under Part I of the Federal Power Act.

The proposed San Vicente Pumped-Storage Water Power Project is comprised of the expanded San Vicente Reservoir, one proposed upper reservoir, conveyance tunnels/shafts, powerhouse and pump station, access facilities, and electric transmission lines. The expanded San Vicente Reservoir will serve as the lower reservoir for the proposed facility. One new reservoir will serve as the upper reservoir for the project.

Four alternative sites for the upper reservoir are being evaluated. The feasibility of the project is primarily attributed to the relatively low incremental costs of adding facilities to those that the applicant is already constructing.

The project will be operated as an energy storage facility, meeting peak electric loads (primarily during the week days) with pump-back operations normally occurring at night and on weekends.

The project will be interconnected to the existing transmission system by a new high-voltage underground or overhead transmission line. The transmission line from each of the alternative reservoir sites would interconnect with the existing San Diego Gas & Electric (SDG&E) Sunrise Powerlink 500-kV transmission line located approximately one-half mile from the project.

The applicant proposes to investigate potential power development in the range of 240 MW to 500 MW. The amount of annual generation from the project will depend on many factors, including: project size, location of the upper reservoir, expectation for the on-peak to off-peak energy price differential and ancillary services market price, and operating constraints. In a typical year, the project would likely generate 15%-20% of the time, usually within relatively short, daily two to four-hour periods. The project also has the capability to generate continuously at different power levels from 100-500 MW.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.