A Solar Bird Death Story Ignites Controversy
By Pete Danko
What the flux?
Renewable energy and its advocates and detractors are having a moment, that’s what, a bout of hysteria after the Associated Press revealed that, OMG, renewables aren’t a magical force capable of keeping our air conditioners humming and big-screen TVs aglow without exacting some toll.
As with wind, the toll here is in birds, birds felled in allegedly troubling numbers by the intense energy of hundreds of thousands of giant mirrors that concentrate sunlight onto boilers atop three 450-foot-tall towers at the Ivanpah Solar Electric Generating System in the Mojave Desert of California.
The phenomenon is called “solar flux.” That it’s an issue with “power tower” technology isn’t breaking news. Desert-dweller and KCET ReWire blogger Chris Clarke has been writing about it for a couple of years. When the Ivanpah plant – developed by BrightSource Energy in partnership with NRG Energy and Google – ceremonially went into service in February, the Wall Street Journal focused a lot of its own energy on “the growing evidence that the technology … is killing birds.” Two months later, the Atlantic published a piece on the Web that said, hyperbolically, that the plant was “incinerating” birds.
But none of that reporting blew up the way last week’s Associated Press story did. The AP’s reach partly explains it – AP stories go everywhere. But the AP also deserves credit for fashioning mostly old information into a highly readable story, particularly the first half of the piece (the part everyone seems to have digested), which is a tour de force of sensational stuff, full of birds being ignited and singed and falling from the sky, with very little tedious detail or complexity to encumber the astonished reader.
Take, for example, one of the most memorable assertions put forward by the AP, in the second paragraph: “Federal wildlife investigators who visited the BrightSource Energy plant last year … watched as birds burned and fell, reporting an average of one ‘streamer’ every two minutes.” Those investigators were from the National Fish and Wildlife Forensics Laboratory, and with their incendiary observation they also admitted, grudgingly, that some of the burning birds actually might represent “the combustion of loose debris, or insects.”
How many, exactly? The investigators didn’t hazard a guess – clearly they had little idea – but if you look at the other data the AP presented in its story, it’s hard to avoid the conclusion that the vast majority of the “streamers” weren’t birds at all.
Consider: An expert brought forth by the Center for Biological Diversity, which is opposing BrightSource’s proposal to build another power tower plant in California, recently estimated that Ivanpah could kill around 28,000 birds a year. This is all bird deaths at the plant, not just those from solar flux; in testimony submitted to state regulators, the expert said that past research showed 70 percent of bird deaths at power tower plants result from birds flying into the heliostats.
Which raises a question: Why the exclusive focus on birds being “ignited” when the evidence is that most of the birds at power tower plants die by collision, not solar flux? Maybe it’s because birds crashing into things is hardly an issue exclusive to power tower solar plants.
In any case, the high-end estimate leaves us with around 8,500 solar flux deaths per year at Ivanpah, which works out to a bird every 20 minutes based on eight hours of operation per day – a far cry from one every two minutes.
On its website, NRG questioned the AP’s use of the “every two minutes” observation, and said the AP itself was at Ivanpah for two and a half hours during which “no falling bird(s) were observed.”
The AP story, with the co-byline Ellen Knickmeyer (an environmental reporter out of the San Francisco bureau) and John Locher (a photographer out of the Las Vegas bureau), didn’t offer first-person observations, so I emailed Knickmeyer to ask if NRG had it right. She declined to comment. NRG, meanwhile, provided a photograph of Locher shooting a picture of one of the lit-up towers – “fully operational” on a “bright, sunshiney day,” the company said.
There’s more about the 28,000 figure, as BrightSource has pointed out: The scientist who offered it, K. Shawn Smallwood, himself called the figure “back-of-the-napkin-level,” saying it was “based on assumptions that I cannot at this time verify as correct.” That’s to Smallwood’s professional credit – he was being honest. Alas, AP’s readers had no idea of his uncertainty.
Amid
Ivanpah’s heliostats, Associated Press photographer John Locher shoots
one of the plant’s three “power towers” on August 13. (Photo courtesy
NRG Energy)
Some birds are inevitably overlooked by search crews and lost to scavengers. Or maybe the area searched isn’t wide enough to find all the birds. Scientists thus adjust the total of recovered birds upward, based on their considered assumptions about how and why birds might be missed. At Ivanpah, plant operators told regulators they found a total of 183 dead birds in April and May. Smallwood assumed crews probably found only 20 percent of the birds actually killed in the areas they searched, so he divided the number by 0.2. Then he divided that result by 0.2 because the area searched was one-fifth as large as it should have been, he said. Then he annualized the two-month figure. Thus, 183 dead birds in two months became an estimate of 28,380 dead birds in a year.
BrightSource’s own expert rejected Smallwood’s assumptions as either having no basis or being exaggerated, and also criticized Smallwood for focusing on a migration-heavy two-month period when longer-term data was available. Using collection for a seven-month period, the company’s expert estimated “between 1,107 and 1,469 fatalities per year directly attributed to the facility” and “between 571 and 898 fatalities per year are expected to be attributed to highly concentrated flux.”
It might be worth pointing out, too, that this isn’t the first time Smallwood has come in at the high end on a bird-death estimate. Last year, Smallwood was in the news when he published a paper that put annual bird deaths from wind power in the United States in 2012 at 573,000, well over previous estimates. The American Wind Energy Association questioned Smallwood’s path to that number, which was to be expected, but other researchers had their doubts, as well.
You see what I mean by tedious detail and complexity? And if you really want to complicate things, check out this study, which estimates that fossil-fuel powered plants kill 24 million birds a year.
