One of, if not the biggest, hurdles to be overcome if solar power plants are to replace conventional fossil fuel-based power plants is cost. To be feasible, solar power plants generally require investment from forward thinking companies or governmental tax incentives. In an effort to make solar power plants - specifically Concentrated Solar Power Towers (CSP) and their accompanying thermal storage systems - more attractive, the U.S. Department of Energy (DoE) has awarded Pratt & Whitney Rocketdyne US$10.2 million to develop technologies aimed at significantly lowering the electricity costs of such solar plants.

Pratt & Whitney Rocketdyne has already developed designs for CSP Tower technology that uses thousands of articulating mirrors (heliostats) that track the sun and reflect solar energy onto a receiver mounted atop a 600-foot-tall (183 m) tower. Based on technology demonstrated in the Solar Two project, the Pratt & Whitney Rocketdyne designs store the solar energy as heat using liquefied molten salt.

The molten salt is circulated into the receiver where it is heated to around 1,000-degrees Fahrenheit (538 degrees Celsius) before being stored in a large insulated tank. Because the molten salt can be stored for days with little heat loss, it is available on demand - at night or on cloudy days - to be pumped to a steam generator to produce steam and drive a standard turbine to generate electricity 24 hours a day.

Pratt & Whitney Rocketdyne has granted a worldwide exclusive license for its molten salt power tower and heliostat technologies to Los Angeles-based solar energy company SolarReserve, which is looking to construct CSP tower plants in California, Nevada and Spain, with a combined output of 300 MW.

As part of the DoE contract, Pratt & Whitney Rocketdyne will strive to lower costs and increase CSP Tower capacity by optimizing system performance and efficiency. It doesn't provide specifics as to how it will achieve this, only saying it will, "use advanced manufacturing techniques that better absorb energy into the receiver; develop a higher-performance, lower-cost second-generation heliostat system; and incorporate a new thermal storage system."

"This award is a key step in reducing the cost of solar power to levels competitive with fossil fuel-based power without the need for federal tax incentives," said Randy Parsley, manager, Global Program Development, Pratt & Whitney Rocketdyne. "We are honored to have been selected."