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July 9, 2007 - 2:07AM

Prognosis is mixed on using state’s hot water for power

Ed Taylor, Tribune

There’s lots of hot water trapped in the earth beneath Arizona, a resource that has occasionally been exploited for commercial purposes such as the Buckhorn Baths in Mesa and Castle Hot Springs in the Bradshaw Mountains north of Phoenix.

GRAPHIC: How geothermal power plants work

With the price of energy soaring and with utilities looking to develop alternative technologies, engineers are looking at the possibility of using Arizona’s underground hot water as an endless source of clean renewable energy to generate electricity.

The prognosis is mixed. Some officials see more potential for geothermal energy in Arizona than others.

Jeff Hatch-Miller, a member of the Arizona Corporation Commission, which regulates electric utilities, thinks Arizona will have to tap into its geothermal reserves to break its dependence on polluting fossil fuels.

“I believe that our universities and industries ought to work on this,” he said. “I’m am not as excited by wind and solar energy because they are part-time resources. Geothermal is not limited by any time of the day or season of the year.”

But Barbara Lockwood, manager of renewable energy for Arizona Public Service Co., sees solar and wind as having more potential in Arizona than geothermal.

“There is a risk (to geothermal energy),” she said. “It costs a lot of money to look for it, and you may or may not find it.”

Lockwood said the best geothermal option for Arizona utilities may be to buy it from other states such as California, where hotter underground water is better suited for running geothermal power plants. Already, APS is procuring geothermal electricity produced in the Imperial Valley west of Yuma, and two weeks ago Salt River Project announced that it has signed a contract to obtain geothermal power from California.

SRP is taking a middle view. John Coggins, manager of resource planning, said SRP has not reached any conclusions about Arizona’s geothermal potential.

“We plan to do our own study,” he said. “We want to confirm what is really out there and see what it might take to develop a project.”

He said the utility plans to hire a consultant before the end of this year to conduct the study — part of a plan to obtain 15 percent of its electricity supplies from renewable sources by 2025.

Although geothermal energy is constantly available, it often has the disadvantage of being in remote locations, Coggins said. To be economically feasible, the hot-water supply must be near a city where the electricity is used or near major transmission lines, he said.

In 2005, APS conducted a geothermal exploration project in the Clifton area in eastern Arizona, where a test well found water that was hot enough to possibly operate a 20-megawatt power plant, said Steve Johnston, APS’ manager for technology development. That would be enough electricity to serve 10,000 homes.

But Lockwood said APS has no plans to follow up that analysis.

“Clifton is promising but not conclusive,” she said, adding that “clearly, the work near Clifton demonstrated there could be some potential. But the resource is not as defined as in California or Nevada.”

To try to boost the industry, the U.S. Bureau of Land Management and the U.S. Forest Service are developing a program to lease blocks of federally owned land in Arizona and other western states for geothermal development.

BLM officials have scheduled a meeting at 4:30 p.m. Wednesday, at the Burton Barr Central Library in Phoenix to hear public comments on western geothermal development.

Much of the current geothermal activity on public lands takes place in California with more than 23 producing leases, followed by Nevada, Utah and New Mexico.


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