SoCalGas tests unusual solar air conditioner

Southern California Gas Co. is trying out an unusual new technology that uses the sun’s rays to provide air conditioning as well as power.

The solar photovoltaic system installed on the roof of the SoCalGas Energy Resource Center in Downey combines mirrors and a computerized tracking system to capture sunlight and focus that energy onto an array of collectors.

The system, made by Cogenra Solar of Mountain View, Calif., produces electricity for the building. It also churns out hot water to run an air chiller instead of using electricity or natural gas for the air-conditioning system.

It’s that combination of products -- electricity and hot water, which can be employed for both heating and cooling -- that makes the system different, said Jeff Reed, director of emerging technologies for Southern California Gas and San Diego Gas & Electric Co., both subsidiaries of San Diego-based Sempra Energy.

“This is a way to use a renewable resource, the sun, to provide most of our cooling needs,” Reed said. Air conditioning, which often accounts for more than half of a building’s electricity consumption, is one of the largest power users in Southern California in the summer, and the demand is greatest when the sun is brightest, “so that makes this even more valuable,” he said.

The Cogenra system provides 10 tons of cooling, or enough air conditioning for two average-sized homes, but is most likely to be used by commercial or industrial operations that have large, flat and sunny roofs, Reed said.

Since 2009, the Downey research center has run a demonstation project of a solar air-conditioning system by Sopogy Inc. of Honolulu. It recently wrapped up a test of a solar AC system by HelioDynamics of Britain. The Cogenra and Sopogy systems together provide about 5% of the Downey center’s air conditioning.

The purpose of these and other demonstration projects is to show customers how to incorporate renewable technologies in their businesses to save energy and money, Reed said. “We get different groups coming through all the time -- building energy managers and the like,” he said.

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