First Solar Trough Plant Since 1990 Underway

Red Rock, Arizona - March 26, 2004 [SolarAccess.com] Arizona's major electric utility APS broke ground on the state's first commercial solar trough power plant, the first such facility constructed in the United States since 1990. Raleigh, North Carolina-based SolarGenix Energy, formerly Duke Solar, is the project developer and will provide the solar thermal technology.

Located at the company's Saguaro Power Plant in Red Rock, about 30 miles north of Tucson, the APS Saguaro Solar Trough Generating Station will have a 1-megawatt (MW) generating capacity, enough to provide for the energy needs of approximately 200 average-size homes. The plant is expected to come online in April 2005.

"This project presents a unique opportunity to further expand our renewable energy portfolio," said Peter Johnston, APS manager of Technology Development. "We are committed to developing clean renewable energy sources today that will fuel tomorrow's economy. We believe solar-trough technology can be part of a renewable solution."

SolarGenix is sure of it too. The company's solar-trough technology uses parabolic mirrors to concentrate the sun's rays to heat mineral oil between 250 and 550 degrees. The fluid is then passed through a heat exchanger to vaporize a secondary working fluid. The vapor is used to spin a turbine, making electricity, then is condensed back into a liquid before being vaporized once again.

"It's a very exciting project for SolarGenix, -- it's the first parabolic trough plant that will be in construction in the U.S. and the world since the demise of LUZ," said Gilbert Cohen, vice president of engineering and operations at SolarGenix.

There are only nine solar thermal plants in the world - all located in California - known as SEGS plants that were built by LUZ International during the 1980s and 1990s. During construction of a tenth plant in 1991, the company filed for bankruptcy citing a combination of eroding Renewable Energy incentives and plummeting energy prices.

Time has passed however, and things have changed since the 1991 collapse of LUZ International. New state requirements for renewable energy coupled with successful research partnerships have revived solar thermal power plant technology.

In this particular case, Arizona's Corporation Commission's Environmental Portfolio Standard, requiring APS to generate 1.1 percent of its energy through renewable sources -- 60 percent through solar -- by 2007, was a major catalyst for the project. This will effectively add one MW of solar capacity towards those requirements.

RPS legislation - the result of growing desires within states to diversify their energy sources through renewable energy - could start a revival of parabolic trough technology echoing the older SEGS projects in California, which have been operating successfully to this day.

Cohen, along with some of the staff at SolarGenix were involved in the older SEGS plants. In fact, that's a big part of why they started Duke Solar, (now SolarGenix).



SolarGenix is teaming up with the geothermal company Ormat who will provide the power block, for the project while SolarGenix will use their proprietary solar collector fields to harness the sun's energy.

"It's an excellent design that will be proven there at the Red Rocks site," Cohen said.

APS, said that historically, the significant capital cost associated with solar-trough technology did not lend itself to smaller applications. However, SolarGenix's solar trough system will combine the relatively low cost of parabolic solar trough thermal technology with the commercially available, smaller turbines usually associated with low temperature geothermal generation plants.

APS owns and operates approximately 4.5 MW of photovoltaic solar generation around the state, and has partnered on a 3 MW biomass plant in Eagar, which came online in February, and a 15-MW wind farm to be constructed near St. Johns.