It's not easy being green: Ivanpah solar plant near Nevada burns a lot of natural gas, making it a greenhouse gas emitter under state law.
Ivanpah Solar Electric Generating System
Basic technology: 320,000 mirrors focus heat on the three boilers mounted on three towers, each 459 feet tall. The boilers make steam that turns turbines, which then produce electricity.Natural gas use: Natural gas is used as a secondary fuel to keep heat in the systems at night and to keep electricity production consistent during periods of cloud cover.
Federal subsidies: $1.6 billion in loan guarantees and $600 million in federal tax credits.
Environmental issues: Carbon emissions from burning of natural gas; loss of endangered species habitat; birds being burned when they fly too close to the boilers.
Benefits: Produces mostly carbon-free energy from the sun. Employed more than 2,500 construction workers; 65 permanent jobs.
Partners: BrightSource Energy, NRG, Google and Bechtel
Tortoises displaced
Biologists found many more desert tortoises, a species threatened with extinction, than expected during the construction of the Ivanpah solar plant. Teams of biologists gathered more than 175 of the reptiles from the site and found another 50 tortoise eggs that were later hatched in captivity.In all, developers spent $56 million capturing, housing, relocating and preserving and restoring tortoise habitat elsewhere.
The administration’s initiative, which uses millions of taxpayer dollars to promote green energy, has been a boon for the Ivanpah plant in the Mojave Desert. But Ivanpah uses natural gas as a supplementary fuel, and data from the California Energy Commission show the plant burned enough of it in 2014 – its first year of operation – to emit more than 46,000 metric tons of carbon dioxide.
That’s nearly twice the pollution threshold at which power plants and factories in California are required to participate in the state’s cap-and-trade program to reduce carbon emissions.
The same amount of natural gas burned at a conventional power plant would have produced enough electricity to meet the annual needs of 17,000 California homes – roughly a quarter of the Ivanpah plant’s total electricity projection for 2014.
The plant’s operators say they are burning small amounts of natural gas in order to produce steam to jump-start the solar generating process. They say burning natural gas always has been part of the process.
Natural gas is used to preheat water that goes into boilers mounted on three 459-foot-tall towers at Ivanpah. This allows heat from the sun – captured by 352,000 mirrors – to make steam more quickly. The steam turns the turbines that produce electricity.
The Ivanpah plant, off I-15 near the Nevada border, also has auxiliary gas boilers that kick in when clouds block the sun.
The primary use of the natural gas “is to optimize the amount of electricity produced from the sun by preparing the facility each day to utilize the solar resource as soon as practically possible, and safely,” said David Knox, a spokesman for NRG Energy, which runs the facility.
COSTS DEBATED
The plant, developed by Oakland-based BrightSource Energy, was approved in 2010 amid questions about its cost to taxpayers and the facility’s impact on the desert environment.
The U.S. Department of Energy granted Ivanpah $1.6 billion in loan guarantees. As a green-energy project, it also qualified for more than $600 million in federal tax credits.
Just before the project broke ground, President Barack Obama praised it in his weekly radio address.
“With projects like this one, and others across this country, we are staking our claim to continued leadership in the new global economy,” Obama said. “And we’re putting Americans to work producing clean, home-grown American energy that will help lower our reliance on foreign oil and protect our planet for future generations.”
Then-Interior Secretary Ken Salazar freed up large expanses of public land for the plant despite environmentalists’ concerns about wildlife habitat and the loss of open space.
Ivanpah was built on 5.6 square miles of mostly undisturbed public land that was home to desert tortoises, a species threatened with extinction, and other species.
David Lamfrom, desert project manager of the National Parks Conservation Association, said information about the amount of natural gas used at Ivanpah shows that the plant is essentially a hybrid operation that requires both fossil fuel and sunshine to make electricity.
He said he doubts the project would have gone forward if it had been billed a hybrid plant.
“It feels like a bait and switch,” Lamfrom said. “This project was held up as a model of innovation. We didn’t sign up for greener energy. We signed up for green energy.”
But Joe Desmond, BrightSource’s senior vice president of marketing, said burning some natural gas allows much more clean energy to be produced from the sun. When electricity demands peak, the plant can produce carbon-free energy into evening hours.
The Ivanpah plant isn’t the only solar facility to use natural gas. It is a supplementary fuel for solar trough plants in Southern California that use curved mirrors to harness heat from the sun to make steam for turbines.
Gas Limitations
The Ivanpah project design includes gas pipelines that feed power-generating areas below each tower. These lines are supplied by a large natural gas pipeline, operated by Utah-based Kern River Gas Transmission Co., that cuts through the Ivanpah Valley.
In 2010, the California Energy Commission required that gas use be limited. A condition of the plant’s license was that heat input from natural gas be no more than 5 percent of the heat the plant captured from the sun.
But in March 2014, after three months of commercial operation, plant operators found they needed to use more natural gas, and they asked the commission for a change in the rules. In August 2014, the commission voted to scrap the 5 percent rule and increased the plant’s annual gas volume limit by 38 percent.
Most of the gas burning occurs in night boilers that “maintain seals and preserve heat,” and in auxiliary boilers that “allow for a faster start-up” and “ride through certain transient cloud events ...” said Knox, the spokesman for plant operator NRG Energy.
He said the plant still meets a state requirement that no more than 5 percent of its electricity production come from burning fossil fuel. This rule, however, does not factor in the gas burned to heat water before enough steam is generated to produce electricity.
That distinction is significant because it could affect the plant’s customers.
Under state law, alternative energy plants can’t use more than 5 percent “nonrenewable” fuel for electricity generation. If a plant goes over that threshold, its electricity can’t count toward the state’s renewable energy goals.
In California, utilities must get 33 percent of their electricity from renewable sources by 2020, and 50 percent by 2030.
Southern California Edison and Pacific Gas and Electric apply the amount of electricity they buy from Ivanpah toward their alternative energy quotas.
On Wednesday, Michael Ward, a spokesman for the state energy commission, said electricity produced at Ivanpah still appears to qualify as renewable energy because natural gas burned at night to maintain the system “does not count against the facility’s fossil fuel allowance of 5 percent.”
But Sadrul Ula, managing director of the Winston Chung Global Energy Center at UC Riverside, said all gas burned should be factored in when evaluating the plant because all of it is necessary for Ivanpah to function.
Ula, a UCR engineering professor, said Ivanpah is performing below expected production levels – while also relying on significant amounts of fossil fuel.
The plant produced just 59 percent of its annual power goal between July 1, 2014 and June 30 of this year. Ivanpah is supposed to generate 940,000 megawatt hours of electricity a year, enough to power about 140,000 California homes.
“It is a poorly performing hybrid,” Ula said.
Plant and U.S. Energy Department officials say production is improving and that Ivanpah is expected to reach its full output after about four years of operation.
Cap and Trade
Meanwhile, state air quality officials are tracking the plant’s carbon emissions.
Ivanpah, like conventional power plants, must participate in California’s cap-and-trade program to reduce greenhouse emissions, because its annual carbon dioxide emissions exceed 25,000 metric tons a year.
In the program, power plants and factories must either reduce carbon emissions or buy pollution credits from those that make reductions beyond their required levels, said Dave Clegern, a spokesman for the California Air Resources Board.
Ivanpah’s status as a cap-and-trade facility “is challenging fundamental assumptions about the project,” Lamfrom said. “If it had been billed as a 75 percent renewable energy project, the [Bureau of Land Management] might have said ‘no.’”
BLM spokeswoman Dana Wilson said she couldn’t say what the agency might have done five years ago under different circumstances.
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