Google-backed plant in US generates electricity with nearly 350,000 mirrors

A windy stretch of the Mojave desert once roamed by tortoises and coyotes has been transformed by hundreds of thousands of mirrors into the largest solar power plant of its type in the world, a milestone for a industry that is testing the balance between wilderness conservation and the pursuit of green energy across the American west.

"The Ivanpah project is a shining example of how America is becoming a world leader in solar energy," US Energy Secretary Ernest Moniz said in a statement after attending a dedication ceremony at the site.

"This project shows that building a clean-energy economy creates jobs, curbs greenhouse gas emissions and fosters American innovation."

The US$2.2 billion complex of three generating units, owned by NRG Energy, Google and BrightSource Energy, can produce nearly 400 megawatts - enough power for 140,000 homes. It began generating electricity last year.

Larger projects are on the way, but, for now, Ivanpah is being described as a marker for the America's solar industry.

While solar power accounts for less than 1 per cent of the nation's power output, thousands of projects from large, utility-scale plants to small production sites are under construction or being planned, particularly across the sun-drenched southwest of the nation.

The opening of Ivanpah was "a dawn of a new era in power generation in the United States", said Rhone Resch, president of the Solar Energy Industries Association, a trade group.

The plant's dedication comes as the US government pushes for development of cleaner power.

President Barack Obama has mounted a drive to combat climate change, proposing limits on carbon pollution from new and existing power plants.

According to US Energy Information Administration data, the cost of building and operating a new solar thermal power plant over its lifetime is greater than generating natural gas, coal or nuclear power.

It costs a conventional coal plant US$100, on average, to produce a megawatt-hour of power, but that figure is US$261 for solar thermal power, according to 2011 estimates. The figures do not account for incentives such tax credits.

Ken Johnson, a spokesman for the solar association, said in a statement that solar systems had seen "dramatic price declines" in the last few years.

That is good for utilities in California, which must obtain one-third of their electricity from solar and other renewable sources by 2020.

The Ivanpah site, about 75 kilometres southwest of Las Vegas, has virtually unbroken sunshine most of the year and is near transmission lines that carry power to consumers.

Using technology known as solar-thermal, nearly 350,000 computer-controlled mirrors roughly the size of a garage door reflect sunlight to boilers atop 140-metre towers. The sun's power is used to heat water in the boilers' tubes and make steam, which drives turbines to create electricity.

The plant can be a startling sight for drivers heading toward Las Vegas along Interstate 15. Amid stretches of rock and scrub, its vast array of mirrors creates the image of an ethereal lake shimmering atop the desert floor. In fact, it is built on a dry lakebed.

Google said in 2011 that it would invest US$168 million in the project. As part of its financing, BrightSource lined up US$1.6 billion in loans guaranteed by the US Energy Department.