Sep. 2--Tucson Electric Power has asked for $25 million in federal stimulus funds to develop cost-effective ways to store and deliver the solar energy it produces.

The money would help fund the "Bright Tucson" project, which is geared to optimize the output of a new 1.6-megawatt photovoltaic array near Tucson International Airport.

In addition to TEP, the Bright Tucson team is made up of local and national companies in the energy industry.

Joe Salkowski, a TEP spokesman, said the project's success is dependent on the stimulus funding. Bright Tucson is the largest of several projects for which TEP, sometimes with other utilities, is seeking stimulus dollars.

One of the challenges presented by solar, Salkowski said, is that the energy supply can vary depending on weather conditions.

"Power from solar panels can disappear at a moment's notice, only to reappear when a cloud passes by," Salkowski said.

Also, peak demand for energy comes in the late afternoon, while solar panels are most productive in midday when the sun is high overhead. So it's more valuable to store that energy for a few hours, he said.

If funding is approved, the project will develop a lithium battery bank and a compressed-air energy storage system next to TEP's solar array on a 20-acre site leased from the Tucson Airport Authority.

The batteries would store solar energy as direct current power, TEP says. The compressed-air system would use solar power to create pressurized air that could drive a turbine and create electric power on demand.

Salkowski said the project would determine if either storage method loses energy and whether they are cost-effective.

Paul Portney, dean of the University of Arizona's Eller College of Management, said that while he didn't know how many jobs might be created directly by the Bright Tucson project, it is a legitimate use of stimulus dollars.

"Finding effective storage systems is essential if renewable sources of electricity like solar power are to reach their full potential," Portney said.

Bright Tucson will spur the manufacturing of solar panels and could help utilities across the country reduce the cost of delivering solar power, said Ardeth Barnhart, co-director of the UA's Arizona Research Institute for Solar Energy, or AzRISE. AzRISE is the co-lead partner in Bright Tucson.

Local companies involved include Solon, a Tucson-based solar manufacturer that will develop the tracking photovoltaic array, and Raytheon, which will provide security systems and systems modeling.

Barnhart said solar-energy storage research has not been tried on this scale.