The U.S. Department of Energy has finalized a $967 million loan guarantee for a 290 MW solar photovoltaic plant on 2400 acres between Yuma and Phoenix. The Aqua Caliente project is now the world's largest PV project under construction.  This follows plans by EnviroMission to build the world's first grid-scale solar updraft tower in Arizona, which is now on the leading edge of big solar power (along with California and Nevada.) Both plants will be using state-of-the art technology to build solar power plants, which together, will power about 160,000 homes.

Upon completion of the financing, NRG Energy in New Jersey bought the project from First Solar of Tempe, AZ. This was an assumed part of the plan. All the electricity from Aqua Caliente will be sold to California power company PG&E under a 25 year contract (The power isn't physically transferred to PG&E. Instead, it goes into an electricity pool where PG&E takes its allotted share at the specified price. Sending power to specific customers from specific locations would obviously be cumbersome, impractical, even if it was possible, which it isn't).

The plant will be completed by 2014 and will create up to 400 solar jobs, as well as increase income for companies in the area providing support services. Photovoltaic plants like this are much better suited for deserts than concentrated solar power (CSP) as they use practically no water, surely an important factor in placing a power plant in arid areas.

Traditional CSP focuses heat from the sun via heliostatically-controlled mirrors to a central tower in order to create steam from water to power turbines. More modern versions of CSP attempt to use much less water by recycling it, but still use far more than PV which mainly uses water to clean the mirrors. However, the EnviroMission solar updraft tower will use no water. The huge tower is hollow with turbines inside. A greenhouse structure surrounds the tower. The sun heats the air in the greenhouse which is drawn up the tower by convection, powering the turbines.

Aqua Caliente is what most people think of as solar power, as it converts the energy of the sun directly into electricity using photovoltaic panels.  But while it got a $967 million loan guarantee from the government, such financing, along with tax credits, could be imperiled by the recent debt ceiling agreement. It's a virtual certainty that such programs will be targeted by conservatives. If the cuts are big enough, it will certainly slow the development of renewable power in Arizona, and elsewhere.