US Solar, APS Receive DOE Study Grant

October 15, 2008

US Solar and its partner, APS, received a grant from the U.S. Department of Energy (DOE) to model and build two new designs for solar thermal storage technologies. The project's goal is to reduce the cost of storing solar thermal energy, a key factor in solar energy's ability to generate electricity at night or during periods of reduced sunlight. 

The $4.35 million project will be directed by US Solar from Tucson, with modeling occurring at the University of Arizona. The final phase of the project will be a full-scale working energy storage plant integrated with APS' existing Saguaro Solar Power Plant, located 30 minutes north of Tucson in Red Rock, Ariz.

While the DOE awarded grants to more than a dozen groups to study solar thermal storage technology, the Arizona-based initiative will be one of only three to be fully integrated with a working power plant. 

US Solar and APS also will receive help from Arizona State University, Georgia Institute of Technology and two Phoenix companies, Klondyke Construction and Ironco Enterprises.

"This initiative brings the best minds in Arizona together to help move Arizona's solar future forward," said Jake Stephens, Director of US Solar. "Further, APS' Saguaro Solar Power Plant is a world-class site for this type of solar project."

Unlike traditional solar-photovoltaic plants, which use direct sunlight to produce electricity, concentrating solar power (CSP) uses the sun's heat. Parabolic mirrors track the sun and focus solar energy on a heat transfer fluid. Once heated, the liquid converts water into steam, which turns the plant's turbines to create electricity.

"APS is committed to solar energy and excited about the opportunity to further the science and drive down its cost," said Barbara Lockwood, APS' Manager of Renewable Energy. "Storage technology is a critical component to the future of CSP."

This will not be the first time APS has helped drive the solar industry. When APS built Saguaro in 2005, it marked the first CSP plant in Arizona and the first to be built in the United States in nearly 20 years. In early 2008, the utility announced plans for the world's largest solar project, the Solana Generating Station. The 280-megawatt CSP plant, which will utilize thermal storage, is scheduled to be operational in 2011. 

About APS
APS, Arizona's largest and longest-serving electricity utility, serves about 1.1 million customers in 11 of the state's 15 counties. In 2008, APS won its second Edison Award in recognition of innovative leadership and operational excellence in the electric industry. Given annually by the Edison Electric Institute, the Edison Award is considered the industry's most prestigious honor. With headquarters in Phoenix, APS is the principal subsidiary of Pinnacle West Capital Corp. (NYSE: PNW)

About US Solar
US Solar Holdings LLC is a developer of utility-scale solar energy projects. Headquartered in Boise, Idaho with operations in Denver, CO and Tucson, AZ. Its principals have experience in the development of more than 5,000 megawatts of energy generation projects.

Steven Gotfried
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