Ausra had proposed to build the Carrizo Energy Solar Farm, a 177 megawatt (MW) solar thermal power plant using the company’s Compact Linear Fresnel Reflector technology, on approximately 1,020 acres (413 hectares) in eastern San Luis Obispo County, California. Early this year it shifted strategic focus to manufacturing equipment for generating solar steam to be used in industrial and energy generating applications.

The site is adjacent to a proposed 550MW solar photovoltaic plant under development by First Solar. It acquired the Topaz Solar Farm as part of its $400m all-stock purchase of the OptiSolar development pipeline earlier this year.

First Solar spokesman Alan Bernheimer says the acquisition of Ausra’s land options will give planners more flexibility to site solar energy projects on the Carrizo Plain, where three large-scale projects had been proposed.

“We’re able to reconfigure our project – not to enlarge it – but to lay it out a little differently, which we think will be an improvement,” Bernheimer tells Recharge. The project footprint is expected to remain at roughly 4,200 acres (1,700 hectares), but the question is which 4,200.

First Solar can now provide corridors for wildlife movement through the project and minimize the use of farmland set aside under a state conservation act for agriculture or open space.

Further, by taking the Ausra solar thermal project off the table, First Solar says the cumulative impact of solar energy development in the area – which includes one of the largest remaining native grasslands in the state – will be reduced. And, San Luis Obispo County will have greater control over how development unfolds. Large solar thermal projects are permitted by the California Energy Commission, while counties have jurisdiction over solar photovoltaic development.

“It really puts the county in the driver’s seat,” Bernheimer says. “They can determine how they want to see solar development go in this region.”

He says large-scale solar PV, while requiring more land than solar thermal, does not require as much water and raises fewer concerns about the height of structures involved.

Ausra had signed a power purchase agreement (PPA) with Pacific Gas & Electric (PG&E) in 2007 for the 177MW output of its project. That agreement has been withdrawn.

Topaz, the largest contiguous utility scale PV project proposed in the US, has a PPA in place with PG&E for the entire output.

Bernheimer says Topaz is in the permitting phase now. The county has contracted for an environmental impact report, which is due in draft next year. After public comments and a finalised report, the county will determine whether to issue a conditional use permit to build the project. He says First Solar hopes to start construction by 2011.

In addition to Topaz, the other remaining Carrizo Plain project is SunPower’s proposed 250MW California Valley Solar Ranch.