Massive Subsidized Solar Project in Calif. Desert Opens

Funded by federal loan guarantees

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 opens Thursday 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 Oakland-based BrightSource Energy, can produce nearly 400 megawatts—enough power for 140,000 homes. It began making electricity last year.