Misaligned mirrors are being blamed for a fire on May 19 at the Ivanpah Solar Electric Generating System in California’s Mojave Desert. According to the San Bernadino Fire Dept., several of the mirrors on one of the arrays were aimed too low and ignited electrical cables on a lower level of one of the boiler towers.
During normal operation, the facility’s nearly 350,000 mirrors, known as heliostats, automatically align to reflect the sun’s rays toward each of the system’s three 459-ft boiler towers, generating high-pressure steam to drive turbines. Each of the 75-sq-ft mirrors is programmed to track the sun and keep the rays focused on the top of the tower. When operating at full capacity, the facility can produce 377 MW of net electricity.
According to plant operator NRG Energy, employees of the facility were able to get the fire under control within 20 minutes, but firefighters still had to climb 300 ft up the tower to check for “hot spots.” NRG Energy operates the Ivanpah solar facility, co-owned by BrightSource Energy and Google Inc.
The fire isn’t the only problem encountered by the concentrating-solar plant since it first began generating power in 2014. Reports of possibly thousands of birds being killed at the Ivanpah site due to the intense heat of the focusing mirrors led to criticism earlier this year from conservation and environmental advocacy groups.
Also, the Ivanpah plant is operating well under capacity, with one other tower already off line for maintenance at the time of the fire. In December 2015, PG&E Corp., which has a power purchase agreement with Ivanpah, asked the California Public Utilities Commission to extend the deadline for Ivanpah operators to meet its power-generation targets.
The commission granted the extension in March, giving Ivanpah an additional six months to meet the targets outlined in the power purchase agreement.