PRIMM, Nevada — 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 growing industry that is testing the balance between wilderness conservation and the pursuit of green energy across the American West.
The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, formally opened Thursday after years of regulatory and legal tangles ranging from relocating protected tortoises to assessing the impact on Mojave milkweed and other plants.
"The Ivanpah project is a shining example of how America is becoming a world leader in solar energy," U.S. Energy Secretary Ernest Moniz said 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 $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.
Larger projects are on the way, but for now, Ivanpah is being described as a marker for the United States' emerging solar industry. While solar power accounts for less than 1 percent 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.
The opening of Ivanpah is "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.
According to U.S. 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 $100, on average, to produce a megawatt-hour of power, but that figure is $261 for solar thermal power, according to 2011 estimates. The figures do not account for incentives such as state or federal tax credits that can affect the cost.
Using technology known as solar-thermal, nearly 350,000 computer-controlled mirrors about the size of a garage door reflect sunlight to boilers atop 459-foot towers. The sun's power is used to heat water in the boilers' tubes and make steam, driving 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," NRG spokesman Jeff Holland said.
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.
According to statistics compiled by the Energy Department, the solar industry employs more than 140,000 Americans at about 6,100 companies, with employment increasing nearly 20 percent since the fall of 2012.