BrightSource Energy and Abengoa argued that Palen Concentrated Solar Power (CSP) project would be able to incorporate thermal energy storage at some point in the future.
BrightSource Energy and Abengoa argued that Palen Concentrated Solar Power (CSP) project would be able to incorporate thermal energy storage at some point in the future. Developing storage capacity is a top priority for regulators and solar companies alike, due to this intermittent nature of solar power and the problems this can pose for integrating solar power into the energy grid.
“Having storage adds a lot of value to a grid that is heavily invested in renewable technology, but does not have storage,” said Frank Wilkins, who until 2011 led the Department of Energy’s efforts to develop concentrated solar power technology. “So from that point of view, Palen’s a good deal.”
Palen would take advantage of concentrated solar power (CSP) technology, which is better at incorporating storage than traditional solar photovoltaic (PV) panels. There are two main types of CSP plants: parabolic trough facilities, which use curved mirrors to direct sunlight at ubiquitous receiver pipes, and power tower facilities, which use flat mirrors to direct sunlight at central towers.
When they proposed building Palen as a power tower facility — its original developer, Solar Millennium, planned to use PV panels before declaring bankruptcy — BrightSource and Abengoa said they wouldn’t be able incorporate energy storage. At an evidentiary hearing last October, BrightSource executive Charles Turlinski told the energy commission that storage wouldn’t be possible because the developers were already under contract to provide most of the energy Palen would generate to Pacific Gas & Electric.
But after Douglas and Hochschild recommended in December that the full commission reject the project, BrightSource and Abengoa changed their tune. While continuing to acknowledge that “financial and policy barriers prevent the actual construction” of thermal energy storage (TES) equipment, they wrote in a February filing with the commission that Palen would be able to “accommodate the incorporation of TES at each power block once the barriers are removed.”
The developers’ emphasis on that possibility — however distant — made a big difference to the commission. Douglas and Hochschild noted in their preliminary decision that power tower technology “allows for more efficient and more cost effective energy storage” than other concentrated solar power technologies, due to its higher operating temperatures.
“While thermal energy storage is not proposed by the Petitioner at this time, we find that the ease of incorporating thermal energy storage into the project is an important, current, and real benefit to the State of California,” they wrote.
The commissioners said several other benefits helped tip the balance in favor of Palen, including the fact that it would contribute to California’s ambitious mandate of reducing greenhouse gas emissions to 1990 levels by 2020. Palen would produce about 7 percent as much carbon per megawatt-hour of electricity as the typical coal-fired power plant, and about 13 percent as much as the average natural gas plant.
Douglas and Hochschild also wrote that Palen would help diversify the state’s renewable energy supply. Neither of the two large-scale solar projects that have started producing electricity in the Chuckwalla Valley, they note, utilize power tower technology, and neither would two other approved projects.
Finally, the commissioners noted, Palen would create hundreds of construction jobs, with an average workforce of more than 600 and a peak workforce of at least 1,200.
But those benefits — greenhouse-gas reduction, portfolio diversity, and job creation — were apparent more than a year ago, when Douglas and Hochschild recommended that Palen be denied. What changed their minds, it seems, was the developers’ emphasis on the potential for Palen to incorporate energy storage.
Anne Baker — senior advisor with the Center for Energy Efficiency and Renewable Technology, a Sacramento nonprofit that advocates for renewable energy — applauded the commission’s preliminary decision. She emphasized that solar technology is progressing quickly, and that energy storage systems continue to improve.
“What we’re seeing across all of the developers is a move to operate as close to 24/7 as we can,” she said. “Solar is constrained to some degree by the sun shining, so storage combined with solar is an optimum situation. We forget these are all new technologies, but we hope that we learn from each of these projects and make the next one better.”
‘Extra scrutiny, not less’
Many environmental groups and activists, however, were appalled by the Palen decision, arguing that the project’s benefits don’t come close to outweighing its costs. For some of those groups, the project’s biggest environmental impact is its potential to kill migratory birds.
In San Bernardino County, the 392-megawatt Ivanpah solar project — the only other large-scale solar tower facility that has come online in the United States — has drawn controversy for killing hundreds, if not thousands, of birds each year. Many of those birds have died attempting to fly through the intense radiation directed toward its solar towers, known as “solar flux.”
Garry George, chapter network director of Audubon California, criticized the energy commission for not examining more closely the U.S. Fish and Wildlife Service’s updated estimates of bird deaths at Ivanpah. The commission wrote in its preliminary decision that while Ivanpah shows that bird deaths at Palen would be “significant and unmitigable … we are unable to estimate with any level of certainty what the magnitude of the solar flux impacts to avian species would be.”
George noted that the Palen solar tower would be significantly larger than any of the Ivanpah towers, and that Palen falls directly within a migratory bird pathway, which Ivanpah does not. He also argued that bird deaths at Ivanpah might be much higher than estimated, because some surveyors have seen birds completely incinerated by solar flux.
“If birds are being singed and there are no caucuses, how do you account for that, when measuring the levels of mortality?” he asked.
Seth Shteir, California desert senior field representative for the National Parks Conservation Association, said the Palen solar tower — which would top out at 750 feet — would be visible from wilderness and back-country areas in the southeastern part of Joshua Tree National Park. He called the energy commission’s decision “the world’s worst birthday present” for Joshua Tree, which is celebrating the 20th anniversary of attaining national park status this year.
“The National Park Service really has mandates to preserve scenic viewsheds, to preserve dark skies — these are key goals it has, protecting resources for future generations,” Shteir said. “And the energy commission’s decision really undermines those goals.”
Asked whether Palen’s climate-change benefits outweigh its environmental costs, Shteir noted that California is already close to satisfying its renewables portfolio standard (RPS), which requires utilities to purchase 33 percent of their power from renewable sources by 2020. Based on contracts it has already signed, Edison projects it will buy 23.5 percent of its electricity from renewable sources by 2020. Pacific Gas & Electric and San Diego Gas & Electric are in even better shape, projecting they’ll hit 31.3 percent and 38.8 percent, respectively, by 2020.
That kind of progress, Shteir argued, means that California should “raise the bar for renewable energy projects, and only invest in ones that don’t jeopardize our national parks, our communities, and things like migrating birds and viewsheds.
“In my mind, that sort of argument — that we must do this because we need to meet our targets for renewable energy — is undermined by the fact that we’re already well on our way there,” Shteir said. “What that means to me is that we should give projects extra scrutiny, not less.”
While BrightSource and Abengoa proposed additional mitigation measures for Palen after receiving the preliminary denial last year, none of those proposals changed the energy commission’s view that the project would “result in significant environmental impacts that cannot be mitigated.”
The commission did, however, decide to approve just one of Palen’s two proposed towers — cutting its environmental costs, as well as its benefits, roughly in half. Douglas and Hochschild wrote that approving just one tower “feasibly lessens most of the … significant impacts while attaining most of the project’s objectives.”
BrightSource and Abengoa had proposed that the commission greenlight both towers, promising only to build the second tower once it could incorporate energy storage. But that proposal didn’t sway the commissioners, who chose only to approve the first tower.
What happens next
The developers could still ask for approval for a second tower later on. BrightSource spokesperson Jennifer Rigney declined to comment on the energy commission’s decision, except to say the company is “encouraged by the Committee’s proposed decision, which is based on the extensive record developed for this project.”
“We believe concentrating solar thermal technology can play an important role in helping California achieve its long-term clean energy goals,” she said in an email.
Palen still has several hurdles to clear before BrightSource and Abengoa can begin construction, which is expected to last 28 months. The full California Energy Commission will consider Douglas and Hochschild’s proposed decision next month, and the Bureau of Land Management still needs to complete the project’s federal environmental review, because it would be located on federal land.
If state and federal regulators sign off on Palen — which seems likely — construction could begin this spring, lasting into 2017. Rigney declined to say whether some electricity would come online by the end of 2016, which would qualify the project for a 30 percent investment tax credit for renewable energy.
BrightSource and Abengoa said in a July filing that they need to begin preconstruction activities this fall in order to meet the terms of a 200-megawatt power purchase agreement with Pacific Gas & Electric (PG&E), which requires Palen to be fully operational by July 2017. A second 200-megawatt power purchase agreement with PG&E was rendered moot by the energy commission’s decision not to approve both towers. But even before that decision, the developers acknowledged in a filing that meeting that agreement’s December 2016 deadline was “improbable,” considering the lengthy permitting process.
If and when Palen comes online, the controversy surrounding the project will no doubt continue, with environmental groups, regulators, and developers closely watching its impacts on migratory birds. Baker expressed hope that as those groups study Ivanpah, Palen, and potentially other power tower projects, they’ll be able to develop effective mitigation measures.
“We build these and we learn from these facilities,” she said. “I applaud the CEC for saying, ‘You know — when we balance everything out, this is where we come out.’
“If we don’t reduce greenhouse gas emissions, we’re going to have terrible impacts on birds and other species,” she added. “So we’re going to do this, and we need to do it with as light a touch as we can.”