Fire at world’s largest concentrated solar power plant caused by own mirrors

Posted on 25 May 2016 by Aiden Burgess

The world’s largest concentrated solar power plant was shut down last week after a small fire broke out at the Ivanpah Solar Electric Generating System, located near the California-Nevada border.

Although no one was injured in the blaze, the fire shut down the Ivanpah plant for several hours last Thursday, 19 May.

Image of the aftermath of the fire at the Ivanpah solar plant - image courtesy of San Bernardino County Fire Department
Image of the aftermath of the fire at the Ivanpah solar plant – image courtesy of San Bernardino County Fire Department.

According to Associated Press, the fire was caused after a misaligned mirror zapped one of the plants towers with a concentrated beam of sunlight.

The most recent update from NRG Energy, the operators of the plant, said the Unit 3 fire was “caused by the heliostats (mirrors) being locked in place in preparation for a maintenance activity (maintenance mode) causing the solar flux to briefly move over a portion of the boiler tower”. The company said it had now put new safeguards that will prevent this from happening again.

The damage to Unit 3 was primarily limited to the aluminum covering of the insulation around pipes, as well as wiring and some valves. NRG Energy said the damage can be repaired “relatively easily” and that it anticipated having the unit back online within three weeks.

According to San Bernardino County Fire Department, upon arrival at the scene, firefighters reported an active fire above the 7th floor on the northwest tower but the fire was quickly brought under control by plant personnel.

Last week’s fire is a setback for the Ivanpah facility, which had been yet to meet the output levels stipulated in its power purchase agreement. Earlier this year the plant was granted an extension on the agreement until 31 July  in order to improve its performance.

The Ivanpah plant, generated 67,300 megawatt-hours electricity in February, up from about 30,300 a year earlier, stated NRG Energy, which co-owns the plant with BrightSource Energy and Alphabet Inc.’s Google.

Mitchell Samuelian, NRG’s vice president of operation for utility-scale renewable generation, told Bloomberg that the improved performance showed the plant’s technology is viable and that the facility is on track to fulfill its contractual obligations and generate approximately 102% of its contracted obligations.

It is as yet unclear what impact the recent setback of the fire will have on the Ivanpah plant’s May output.

Plant responds to earlier criticism

In 2015, BrightSource Energy, responded to a Wall St Journal story which critiqued the Ivanpah plant’s performance.

BrightSource Energy’s response highlighted that March 2015 was second most productive month ever at the site and that, in April 2015, it exceeded that level of generation within just the first two thirds of the month. This production output continued in May 2015 when the plant set a new MwH production records for each unit and for total plant output in a single day.

Another criticism of the Ivanpah plant has been that it has a detrimental impact on bird species. However, BrightSource Energy also emphasized in another press release last year that results of its Ivanpah Avian and Bat Monitoring Plan Annual Report indicated that migratory bird mortality during the monitoring period was low, with the facility having a minimal avian impact on the local environment.

The Ivanpah operation explained

The massive 3,500-acre Ivanpah solar plant uses 173,000 heliostats, which each have two mirrors, generated approximately 652,300 MwH in 2015. The mirrors focus sunlight onto three 495-foot towers. The heat generated is used to warm water, which creates steam to drive turbines and generate electricity.

The plant generates enough electricity to power about 140,000 homes and is part of California’s clean energy goal of drawing 50% of its energy from renewables by the end of 2030.

When it opened in February 2014, the Ivanpah Solar Power Facility was the world’s largest concentrated solar power (CSP) plant.

Unlike 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.

The plant requires burning natural gas each morning to get the plant started. In 2014, the plant reportedly burned 867,740 million BTU of natural gas emitting 46,084 metric tons of carbon dioxide. If that gas had been used in a conventional fossil fuel plant, it would have generated only 124,000 MwH of electrical energy.

Ivanpah used that gas plus solar energy to produce 524,000 MwH of electrical energy (more than four times that of the referenced conventional plant). In 2015, according to the Electricity Data Browser, the natural gas consumption at the plant decreased to 564,814 million BTU, while the total energy output had increased to 652,300 MwH.

Although it is currently the world’s largest solar plant of its kind, the Ivanpah Solar Electric Generating System will be dwarfed by the $9bn Noor CSP based in Morocco, which is due to be finish construction in 2018.