Green Desert: Birds vs. Windmills: the battle continues

The impact of renewable energy projects on migrating birds is a story that has — to stretch an obvious metaphor — taken flight.

My Nov. 10 story on bird deaths at solar thermal and photovoltaic plants in Riverside and San Bernardino counties was picked up by USA Today, as well as Pasadena public radio station KPCC — I did a taped interview — and even, I heard from a friend, got a mention on the The Drudge Report.

Now we have yet more information with the release Monday of BrightSource Energy’s October monitoring reports from its Ivanpah solar project in eastern San Bernardino County. As initially reported by Chris Clarke at KCET, the total dead bird count at the 377-megawatt solar thermal plant was 53, with 22 listed as having melted or scorched feathers.

That’s up from September’s tally of 34 mortalities, 15 with melted feathers. The damage is likely caused by the birds flying through the intense radiation coming off Ivanpah’s 300,000 reflecting mirrors —about 100,000 surrounding each of the plant’s three 459-foot solar towers. The tightly focused radiation heats liquid in boilers at the top of the towers, creating steam to run turbines.

The October tally also had a high number of small songbirds, such as yellow-rumped warblers (13, eight with melted wings) and house finches (eight, six with melted wings).

In the meantime, a new study published online provides updated figures on bird deaths at wind farms. “Estimates of bird collision mortality at wind facilities in the contiguous United States” will be published in December in the journal Biological Conservation, but is already available online, with Clarke again doing an early report.

The authors — Scott R. Loss, Tom Will and Peter P. Marra — scoured various literature sources to find the most up-to-date mortality figures, particularly focusing on the impact of the replacement of older turbines with lattice-style foundations with the newer, taller monopole machines. Numbers from the San Gorgonio Pass were not included because the only available studies he could find on the pass were based on unadjusted raw data that would not have given a true picture of mortalities in the area, Loss said in an email.

According to the most recent figures from the American Wind Energy Association, California is No. 2 on megawatts of installations with 5,587 megawatts after Texas, which has 12,214 megawatts. Iowa is third with 5,133 megawatts.

Even without San Gorgonio, the authors found mortality rates for monopole turbines in California leading the nation, averaging 108,715 per year, compared to 22,177 per year for the rest of the western states. Comparable figures for the eastern states were 44,006 and for the Great Plains states, 54,115.

Breaking it down to bird deaths per turbine, California is again the highest, with 7.85 per turbine versus the Great Plains, which was lowest at 2.92 per turbine.

If you want to put it in terms of megawatts, in California, we’re losing about 18.76 birds per megawatt of wind power produced. One megawatt can power between 750 and 1,000 homes. The study also found that taller turbines could be related to higher bird mortality rates.

Putting these figures in some kind of dispassionate, objective context is always difficult. No one likes to think of songbirds — symbols of all that is free, fragile and beautiful in nature — flying through a solar field with their wings melting, like so many pint-sized Icaruses soaring too close to the sun. Images of migratory birds getting shredded by turbines are equally grisly and distasteful.

At the same time, the issue pushes us to examine our expectations that what we call clean or renewable energy should be impact-free when, in fact, it isn’t and can’t be. Will the problem irrevocably tarnish public perceptions of large-scale renewable energy projects? Should we halt or at least slow the development of these plants on public land until we can figure out a solution? What kinds of mitigation or compensation should solar and wind developers be required to undertake in the interim?

The answers to such questions are complex and a matter of context. Every form of energy generation has direct or indirect environmental impacts of some sort, as do most forms of human economic development. The impacts we find personally and socially acceptable may change over time depending on shifting priorities and sensibilities.

Millions, if not billions, of birds die yearly from collisions with buildings, windows and electric wires. We haven’t stopped building any of these structures. Still, the fact that the number of birds killed at wind and solar farms appears smaller in comparison should not be seen as a reason to say such deaths are less significant.

Officials at the U.S. Fish and Wildlife Service stress that the first step must be solid, scientific research. Every bird carcass found at large-scale solar projects on public land is now kept, put in a freezer and turned over to the agency for autopsy. More needs to be done.

For example, at solar thermal projects such as Ivanpah, the carcasses found on site may be only a portion of the deaths or injuries to birds flying over the site. Some may have their wings singed, but make it through the project site only to come down and die nearby. Should biological monitors also regularly survey a certain radius around the project? Is there a way to electronically monitor such a zone?