The world's largest solar energy plant has officially opened in California.
Sprawling across 3,500 acres in the Mojave desert, Ivanpah solar thermal power plant can produce nearly 400 megawatts of energy - enough to power 140,000 homes.
The opening of the $2.2 billion complex of three generating units represents a major milestone in the growing green industry.
US Energy Secretary Ernst Moniz said the centre showed the US was leading growth in the sector. Speaking at the opening, he said:
The plant consists of three 459-foot tall towers each with tens of thousands of robotic, heliostats that angle sunlight towards a water boiler.
Each heliostat consists of two garage size doors. The reflective area of each heliostat is 163 square feet.
Seen from above the 173,500 heliostats together look like a lake, reflecting the blue sky, but this has proved problematic for birds.
Government documents show dozens of dead birds from sparrows to hawks have been found on the site, some with melted feathers. The suspected causes of death include collisions with mirrors and scorching.