Over the past few years, as giant photovoltaic solar farms have been sprouting up across the U.S. Southwest and coming online in stages, two giant concentrating solar power (CSP) plants have also been racing to completion and commercial operation testing. It now appears that Abengoa Solar’s Solana system, a solar thermal trough CSP system, has taken the lead.
On Oct. 9, Abengoa said that the 280 megawatt Solana plant—the first commercial CSP plant in the U.S. with thermal energy storage—passed commercial operation tests. The other CSP system racing towards coming online, the BrightSource Ivanpah Solar Electric Generating System (SEGS), completed its first sync to the grid on Sept. 24. However, that was for only one of the system’s three solar power towers. The Ivanpah system is much larger than Solana at 377 megawatts. Both projects concentrate the sun’s heat to superheat water into steam, which is then used to turn a turbine generator, much like in a conventional coal or nuclear plant—without the risk of nuclear contamination or emissions.
“This milestone marks a major accomplishment for Abengoa and the concentrating solar power industry,” the solar company said. Construction on the project began in 2010. About three-and-a-half years later at a pace of roughly 75 megawatts a year, it’s ready to start commercial operations and supplying solar electricity to Arizona Public Service under a 30-year power-purchase agreement.
The project reached the milestone earlier this week. “On Monday, October 7, [Solana] successfully fulfilled production forecasts required to date and testing for commercial operation. These tests included operating at the turbine’s full capacity while charging the thermal storage system, continuing to produce electricity after the sun went down, and starting up the plant and producing six hours of electricity using only the thermal storage system,” Abengoa said.
Since both Ivanpah and Solana concentrate the sun’s energy and use conventional steam turbines for energy generation, their implications for other uses are abundant. While both projects are stand-alone projects, CSP has already been used in the U.S. to supplement energy generation at coal-fired power plants. Similarly, the technology has been used to heat water for industrial practices like for mining oil and gas.
The addition of thermal energy storage at Solana adds a new, important component to CSP however, by storing excess thermal energy in molten salt, it allows the power plant to operate more like a conventional power plant with predictable, dispatchable electric generation. “Solana’s thermal storage system, without the use of the solar field, can produce clean energy for six hours at maximum power. These six hours will satisfy Arizona’s peak electricity demands during the summer evenings and early night time hours,” the company said.
As both projects near commercial operation, this provides an important turning point for CSP, which could make it easier to invest in CSP projects in the future, now that Ivanpah and Solana are proving their ability produce the promised energy output. Solana, for instance, received a federal loan guarantee for $1.45 billion through the Department of Energy’s Federal Loan Guarantee Program. Given the scale and newness of the technology in the U.S., Solana wasn't able to attract other funding without the guarantee. However, now that the plant has started to produce solar power as anticipated, that could change.