By Lena Babaeva Coradini

Litigation seeking to block the construction of new solar thermal power plants raises new questions about the environmental impact of such projects.

Just weeks after regulators approved the last of nine multibillion-dollar solar thermal power plants to be built in the Southern California desert, a storm of lawsuits and the resurgence of an older solar technology are clouding the future of the nascent industry.

The litigation, which seeks to block construction of five of the solar thermal projects, underscores the growing risks of building large-scale renewable energy plants in environmentally delicate areas. On Jan. 25, for instance, Solar Millennium withdrew its 16-month-old license application for a 250-megawatt solar station called Ridgecrest, citing regulators’ concerns over the project’s impact on the Mohave ground squirrel.

At peak output, the five licensed solar thermal projects being challenged would power more than two million homes, create thousands of construction jobs and help the state meet aggressive renewable energy mandates. The projects are backed by California’s biggest utilities, top state officials and the Obama administration.

But conservation, labor and American Indian groups are challenging the projects on environmental grounds. The lawsuits, coupled with a broad plunge in prices for energy from competing power sources, threaten the ability of developers to secure expiring federal loan guarantees and private financing to establish the projects. Only one developer so far, BrightSource Energy, has obtained a loan guarantee and begun construction.

Like so many of this state’s troubles, the industry’s problems are rooted in real estate.

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But many of the areas planned for solar development — including the five projects being challenged — are in fragile landscapes and are home to desert tortoises, bighorn sheep and other protected flora and fauna. The government sped through some of the required environmental reviews, and opponents are challenging those reviews as inadequate.

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The risk that the suits will succeed in blocking construction could make it more difficult for the builders to get federal loan guarantees or attract private financing.

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The conflict over the California projects has already accelerated a shakeout among competing solar technologies.

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Solar thermal developers never expected to run into such difficulties. But federal law requires that projects on public lands undergo extensive environmental review and allows citizens to sue to enforce those laws. Three of the four solar thermal power plants that have escaped legal challenge are planned for private land.

The progress of those legal actions will be interested to monitor, and to see what impact they will have on the solar industry.