San Diego System Profile

The Energy Center system was originally built in 1971 by an affiliate of local utility San Diego Gas and Electric. It was one of the first cooling-only district energy systems built in the United States. The system underwent a major renovation in 1999, adding eight new rooftop cooling towers and 2,600 tons of gas-fired turbine-driven chiller capacity. The system also cogenerates 1,600 kW of electricity – enough to meet nearly 30 percent of the plant’s peak power requirements. NRG Thermal acquired the system in 1997.

Services provided: Chilled water for air conditioning. Customers can also receive a review of their annual chilled-water usage as well as assistance with budget forecasting for chilled-water service and other utilities.

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Area served: 4 square miles of downtown San Diego.

Buildings on system: Approximately 20.

Building space served: More than 4 million square feet.

Total system capacity: 8,000 tons of chilled water.

Plant: The Energy Center operates a chilled-water plant on Kettner Boulevard in San Diego’s central business district. Built in 1971, the plant underwent a major renovation in 1999. It is equipped with absorption chillers and a turbine-driven chiller. Sixty-five percent of the plant’s capacity relies exclusively on electric-driven chillers; 35 percent of the capacity is produced utilizing natural gas as fuel. The system also cogenerates 1,600 kW of electricity – enough to meet nearly 30 percent of the plant’s peak power requirements.

Distribution network: 4 trench miles of chilled-water piping.