A windy stretch of the Mojave Desert has been transformed into the largest solar power plant of its type in the world by an installation of hundreds of thousands of mirrors.
The move is a milestone for a growing industry that is testing the balance between wilderness conservation and the pursuit of green energy across the West.
The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles (13 square kilometres) of federal land near the California-Nevada border, formally opens Thursday.
The site, about 45 miles (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 459-foot (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.
While many people are familiar with rooftop solar, or photovoltaic panels, "these are a little bit different. This takes the sun's rays and reflects them onto towers," said NRG spokesman Jeff Holland.
The plant can be a startling sight for drivers heading toward Las Vegas along busy Interstate 15. Amid miles of rock and scrub, its vast array of mirrors creates the image of an ethereal lake shimmering atop the desert floor. In fact, it's built on a dry lake bed.
It opens after years of regulatory and legal tangles ranging from relocating protected tortoises to assessing the impact on Mojave milkweed and other plants.
The $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 making electricity last year.
The Western Watershed Project is continuing to push a lawsuit against federal agencies that reviewed the Ivanpah project. Its California director, Michael J. Connor, said alternatives to the site were not considered and serious environmental impacts, including fragmenting the tortoise population, were ignored.
"Do we really need to have these giant plants first, or is it better to generate solar power on people's roofs, the place it's going to be used?" Connor asked.
NRG did not respond to a request for comment on the lawsuit.
