Solar air conditioners to chill California utility

news.cnet.com
July 21, 2009

The Los Angeles-based utility said on Tuesday that it has chosen two solar concentrators to measure how effective they are at cooling. The units will be installed on the roof of its Energy Resource Center (ERC) in Downey, Calif. Both products--one from Hawaiian start-up Sopogy and another from HelioDynamics in the U.K.--reflect and concentrate incoming sunlight onto a pipe to heat water. That heated water is used in place of gas or electricity to power an industrial absorption chiller, which creates cold air using a heat exchanger and compressor.

Using the sun for cooling has long been considered an excellent application for solar energy because the air conditioning load corresponds with daylight hours Concentrators can be more efficient and take less space than photovoltaic panels which make electricity, according to Southern California Gas. Sopogy's MicroCSP is essentially a shrunk-down version of the parabolic troughs used in giant solar energy plants. HelioDynamics' concentrators can produce both heat and electricity.

Southern California Gas chose these concentrators because they are small enough to fit on an office building roof and are modular, said Hal Synder, vice president of customer solutions. Each unit is capable of providing enough cool air for three average-size homes. Air conditioning can be half of a commercial building's electricity use. The utility plans to test these concentrators for two years and will add electricity production to the site in a year.

There are already a handful of companies developing concentrators for cooling. Chromasun, started by one of the founders of concentrating solar company Ausra, has developed a solar collector designed for commercial and industrial customers which can reduce energy bills significantly by cutting peak-time usage.

Meanwhile, there is already a solar cooler in operation. Late last year, famed piano maker Steinway & Sons installed a solar cooling system that uses reflective troughs. Like the SoCal Gas systems, the heat feeds an absorption chiller to provide cool air and dehumidify Steinway's buildings. In the winter, it provides heat.