APS Completes First Solar Trough Power Plant in Arizona;
and the First Built in the U.S. in 17 Years

APS news release April 20, 2006 Phoenix, AZ -
Arizona Public Service Company (APS) is inviting the public to help commemorate a power plant that looks nothing like - and is unlike - any other electricity-generating plant in Arizona.

Arizona's first solar trough power plant features more than 100,000 square feet of parabolic-trough shaped mirrors and stands more than 15 feet tall. Neatly aligned in 6 rows - each more than 1,200 feet long that sit on a stretch of desert between Phoenix and Tucson - the mirrors already are quietly concentrating the sun's energy and producing one megawatt of clean electrical power. This output is enough electricity to meet the demands of about 200 homes.

The plant uses a solar thermal generator and mirrors to concentrate the sun's energy to heat oil. The heat from the oil is then used to drive a turbine/generator that produces electricity.

Commercial operation of the solar trough now makes APS the largest producer of solar energy in Arizona, with more than six megawatts of solar electric generating capacity.

The solar trough is also unique from other Arizona solar generating facilities because it can actually store energy, a trait that traditional solar plants are not capable of performing. This storage capability allows the solar generators to supply electricity when needed - not just when the sun is shining. The plant also is the first to combine solar trough technology with an Organic Rankine Cycle Power Block, typically used in geothermal and biomass applications. The block allows the plant to produce more power at lower temperatures.