The San Diego County Water Authority’s Lake Hodges Pumped Storage Project is now fully operational and delivering up to 40 megawatts of electricity to the region, helping San Diego Gas & Electric meet San Diego County’s energy needs in the hot weather of late summer.
The project, which moves water between Lake Hodges and the Olivenhain Reservoir, provides 20,000 acre-feet of emergency water storage. Its twin 28,000-horsepower pump turbines also can generate enough power for 26,000 homes. The first turbine began adding power to the grid in September 2011; the second finished testing and started operations in late August 2012.
“This is a great project because it benefits our region in three important ways,” Water Authority Board Chair Michael T. Hogan said. “It enhances the reliability of the region’s water supply, it helps meet the region’s electricity demands and it benefits ratepayers by generating revenue to offset part of our operating costs.”
The Lake Hodges project is a key part of the Water Authority’s $1.5 billion Emergency Storage Project, a system of reservoirs, pipelines and pumping stations designed to ensure that up to a six-month supply of locally stored water will be available for the San Diego region if a disaster or other event interrupts imported water deliveries.
The project generates hydroelectric power on demand for the region by sending water from Olivenhain Reservoir through the pump turbines as it flows approximately 770 feet downhill into Lake Hodges. Power is generated during daylight hours when electricity demand is highest, and water is pumped back into Olivenhain Reservoir during off-peak hours when energy costs less.
The Water Authority has a long-term power purchase agreement with SDG&E that includes terms for buying power produced by the project and a reduced rate on energy required to operate the project.
“The Lake Hodges water facility is a unique project that will enhance reliability to the electric grid by providing additional local power to our customers here in San Diego, especially when supplies may be tight,” said Michael R. Niggli, president and chief operating officer for SDG&E. “This additional resource allows SDG&E to help meet our customers’ needs by having a flexible fast responding asset that will provide additional power to the grid quickly and reliably when needed, and help us integrate intermittent renewable power sources. We extend our congratulations to the San Diego County Water Authority for making this important project possible.”
The project could produce between $2 million and $3 million a year in revenue plus additional savings from lower energy costs. The exact amount will depend on how frequently the project is needed to help meet peak power demands and other factors.
“This savings and revenue will be used to help meet our budget needs and manage future water rates,” Hogan said. “This will help control our costs for decades.”
In addition to producing hydroelectric power at Lake Hodges, the Water Authority has generated electricity at its Rancho Peñasquitos Hydroelectric Facility near Interstate 15 and Mercy Road since December 2006. The facility, which can generate up to 4.5 MW of power as water flows through the Water Authority’s Second Aqueduct, produced more than $1 million in revenue during the last fiscal year.
The Lake Hodges project connects the city of San Diego’s Lake Hodges to the Water Authority’s Olivenhain Reservoir and the regional water distribution system for the first time. Previously, Lake Hodges water was available only to local customers of the Santa Fe Irrigation District and San Dieguito Water District.
The connection, via an underground pipeline, will make 20,000 acre-feet of water in Lake Hodges available for emergency use around the county. An acre-foot is about 325,900 gallons, or enough to supply two average single-family households of four people for a year. The project enables the Water Authority to add imported water to Lake Hodges to provide a more consistent water supply and lake level during dry years. It can also move captured runoff out of Lake Hodges during wet years for storage elsewhere, reducing the potential for lost water from overflows of the reservoir’s dam. Lake Hodges has the largest watershed of all lakes in the region.