The Arizona desert near the sleepy town of Gila Bend stands to become home to the world's biggest solar plant in 2011, but only if Congress votes to renew the clean energy tax credit due to expire at the end of this year.

The Solana project, to be built by Spain's Abengoa engineering group and forecast to produce 280 megawatts at peak, is just the largest of the solar and renewable energy projects put at risk by the expiration of the tax credit. More than 40,000mW worth of clean power, not to mention the jobs and economic growth it will stimulate, also hang in the balance.

The burgeoning solar and renewable industry depends on the tax relief offered by the Production Tax Credit (PTC) and the Investment Tax Credit (ITC) to offset the price of still-new technology and build capital. Abengoa CEO Santiago Seage put it bluntly in an interview with the Arizona Republic: If the tax credit is not renewed, the plant “will not happen.”

Now is one of the best opportunities for citizens to significantly affect America's energy policy and progress towards renewable energy. You can add your signature to a petition being prepared by the American Council on Renewable Energy (ACORE), and contact your senator. That goes double for all you Arizona EnviroWonks, because your senator, John McCain, has been absent from two successive votes that might have ensured that these projects are funded, and we can't afford for him to play hooky on another.

According to ACORE, the credits need to be extended by March 1, 2008, to avoid putting these projects at risk.