The cause of a Friday fire that shut down part of the world's largest solar power plant is still under investigation, after mirrors focused the sun's rays on a 452-ft high water boiler tower, melting steam ducts and water pipes.
David Knox, spokesman for Ivanpah plant operator NRG Energy, said the company's focus right now is to access the damage, investigate the cause and develop and implement a repair plan.
It is not yet known how long the plant will be down.
The fire at the Ivanpah Solar Electric Generating System, located in the Ivanpah Dry Lake near the California-Nevada border, forced firefighters to climb about 300 feet up a water boiler tower that's superheated by tens of thousands of mirror to create steam to run a turbine.
The blaze was actually extinguished by plant workers before the firefighters even arrived, according to Knox. No one was injured in the fire.
The San Bernardino County Fire Department said the fire lasted about 20 minutes and was caused by mirrors being misaligned and focusing the sun's rays on pipes and wires about two-thirds of the way up the boiler tower.
The plant has three units, each of which have more than 100,000 computer-controlled mirrors that focus the sun's rays on three separate boiler towers. The fire broke out on Unit 3, which had to be shut down. Unit 2 is currently undergoing maintenance, Knox said, meaning only one of the three units is supplying power to California residents.
When it opened in February 2014, the Ivanpah Solar Power Facility was the world's largest Concentrated Solar Power (CSP) plant. Instead of using photovoltaics, which convert solar energy into direct current using semiconductor materials, CSP plants generate electricity in much the same way as conventional fossil fuel power plants do, by boiling water into steam, which then drives an electric turbine.
All together, Ivanpah's three steam generator units create up to 392 megawatts (mW) of power during the day, which means the plant is currently at one-third of its capacity.
Knox said the damage the Unit 3 from the fire was not extensive.
"Really, just the aluminum covering on the steam pipes. It looks a lot worse in the pictures," he said. "We're surveying what to do to get back on line as quickly and safely as possible."
It was the first such fire at the Ivanpah plant, which opened about two years ago, Knox said.