But photovoltaic 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, as much as twice what an average coal-fired plant uses.
One solution. Build solar on unused and underused farmland where the farmer owns water rights. Often, solar will use less than agriculture, and the farmer gets an income stream. Others plan solar in the Mojave on public land with unused aquifers, which is certain to bring lawsuits from environmentalists and local residents.
The politics of water in the American Southwest are as brass-knuckled as politics gets. For Arizona to get this far on solar without war breaking out shows, I think, a real consensus building towards putting solar on what was once cropland. Also, by reusing waste water and developing new methods that use less water, concentrating solar could use substantially less water.