AZ BLDG SUN, WORRYING ABT WATER

Amid state's push for solar power, water-supply worries arise
Shaun McKinnon, January 17, 2010 (The Arizona Republic)

"Arizona can offer solar-energy developers legendary sun-drenched skies and thousands of empty square miles but not nearly so ample a supply of a third essential resource…Water.

"As the state…[seeks] the jobs and tax revenue a vibrant solar industry would create, officials face a fundamental and all-too-familiar obstacle…Some of the most widely used and economical solar-energy technologies require significant amounts of water, as much as or more than the coal, natural-gas or nuclear power plants the solar projects are meant to replace…Yet the sites most attractive for solar plants…are also some of the hottest, driest parts of Arizona…Should Arizona support a renewable resource with one that is finite?…Sen. Jon Kyl, R-Ariz., warns that an uninformed embrace of solar power could threaten the state's already uncertain water resources. But others say the conflict is not so clear-cut. Solar energy's benefits - a free fuel source, no air pollution, no hazardous waste - could still balance or even outweigh its demand for water."

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"…Stung by the real-estate crash, [Mojave County] officials rolled out a red-carpeted welcome to several large solar projects that could help the state make deep inroads in fulfilling its solar-energy promise…[F]our projects have been proposed, and two are on the regulatory fast track and could begin generating power within two or three years.

"The first two plants could require more than 1.5 billion gallons of groundwater annually…as much as a city the size of Kingman, population 27,000, requires in a year…[P]hotovoltaic arrays can't yet fill large electricity demands cheaply, so most of the big solar projects proposed in Arizona would operate with a technology called concentrating solar…It uses the sun's energy to create steam that turns turbines to generate electricity, much as traditional power plants do. Water is needed to produce steam and cool the system afterward…The water used for steam can be reused, but much of the rest is lost to evaporation…"

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"…[A]reas most at risk of running short of water, including much of southern and central Arizona, match up closely with the areas where solar-power projects are expected to develop…Some planned projects…would be built on land once used for agriculture, often atop deep aquifers. Water is already available - as groundwater rights belong to the landowner - and in most cases, the plants would consume less than the farms they replace…[S]uch a reallocation of water from farms to solar power represents a wise choice for Arizona…[Treated effluent and recirculated wastwewater could also help somewhat and a shift to dry cooling technology is the long-term solution]…

"…[But] projects staked out on parcels of untouched public lands, where the only source of water is aquifers whose amounts of water are either unknown or difficult to measure [like the Mojave projects would be bad choices for use with current water cooling technology]… Mohave County officials say the power plants pose no threat to the region's drinking-water supplies…With few exceptions, state water laws would not prevent a solar-power plant from pumping the groundwater aquifers around it. State regulators hope they can encourage energy providers to build [wisely]…[T]he demand for solar power has grown in recent years, fed in part by local, state and federal tax breaks…[and an RES requiring] utilities to obtain a minimum of 15 percent of their electricity from renewable sources by 2025…"