Green Wombat

photo: Todd Woody

California utility PG&E on Monday announced two new Big Solar deals that will likely to ramp up the debate over solar thermal power plants’ thirst for water in the desert Southwest. As I write in The New York Times:

The West’s water wars are likely to intensify with Pacific Gas and Electric’s announcement on Monday that it would buy 500 megawatts of electricity from two solar power plant projects to be built in the California desert.

The Genesis Solar Energy Project would consume an estimated 536 million gallons of water a year, while the Mojave Solar Project would pump 705 million gallons annually for power-plant cooling, according to applications filed with the California Energy Commission.

With 35 big solar farm projects undergoing licensing or planned for arid regions of California alone, water is emerging as a contentious issue.

The Genesis and Mojave projects will use solar trough technology that deploys long rows of parabolic mirrors to heat a fluid to create steam that drives an electricity-generating turbine. The steam must be condensed back into water and cooled for re-use.

Solar trough developers prefer to use so-called wet cooling in which water must be constantly be replenished to make up for evaporation. Regulators, meanwhile, are pushing developers to use dry cooling, which takes about 90 percent less water but is more expensive and reduces the efficiency –- and profitability – of a power plant.

NextEra Energy Resources, a subsidiary of the utility giant FPL Group, is developing the Genesis project in the Chuckwalla Valley in the Sonoran Desert. The twin solar farms would tap about 5 percent of the valley’s available water.

You can read the rest of the story here.