How many birds are we talking about?

As you know, the impact that wind turbines may have on migratory birds has dominated the conversation about the proposed wind farm on the Kenedy Ranch, which is currently being challenged by a coalition of environmental groups plus the neighboring King Ranch. As much as the issue has been in the news, I can't recall seeing any actual numbers being mentioned in them. Are we talking hundreds, thousands, what? This Brownsville Herald story is the first article I've seen to include such data.

Despite the companies' reassurances, alliance members say they are concerned about the wind projects' impact on endangered and threatened bird species in the region, as well as on the coastal habitat. The tall turbines and their fast-spinning blades could lead to substantial bird kills, the groups say. The needed infrastructure -- including concrete bases for the towers and roads running throughout the site -- will deplete natural habitat, they said.

Wind turbines made today typically have towers from 200 to 260 feet tall, with rotors from 150 to 260 feet in diameter, according to the National Wind Coordinating Committee. At their tips, the blades can turn as fast as 138 to 182 miles per hour.

Bird fatality rates at other wind-turbine sites have varied widely, from less than one bird per turbine at a site in Oregon to 10 per turbine at a site in Tennessee. The average, according to the National Wind Coordinating Committee, is two per turbine per year.

The companies counter that they've conducted assessments of the bird populations in the area, and concluded the turbines would cause minimal bird fatalities.

"Since 2004, we've been doing migrating bird studies, breeding bird studies," said Jan Johnson, spokeswoman for PPM Energy.

According to PPM, these studies have shown, for example, that raptors like the aplomado falcon -- one of the species of concern to the alliance -- fly west of the site and wouldn't be affected.

Babcock & Brown has come to similar conclusions, Shugart said. Also, the company is planning to construct turbines and the connecting roads so as to minimally disturb wetlands, he said.

"We've worked with local environmental agencies and the Army Corps of Engineers on the project, on avoiding the wetlands," Shugart said.

Most of the land will remain undisturbed, he said.

"It's not like a sprawling Wal-Mart parking lot," Shugart said.

However, because the companies have generally funded their own studies, and in some cases haven't made the results public, alliance members are unconvinced.

"It's not the same as having people from environmental agencies, qualified biologists, discuss the studies that need to be done," said David Newstead, president of the Coastal Bend Audubon Society. "It needs to be legitimate, peer-reviewed research. ... In Texas there are essentially no studies like that."

Okay, so here we have a range of 250 to 2500 bird deaths per year, with 500 being roughly the expected value. Frankly, that's less than I'd been anticipating, given some of the things that have been said over this proposal. Perhaps now someone can take the next step and ask the two sides in this dispute what numbers they think are reasonable. Would 250 dead birds per year be acceptable to the Coastal Habitat Alliance? Would 2500 per year be unacceptable to PPM Energy? Let's set some parameters here, so we can know what we're working with.

Interestingly, this story does not mention the one place that's been held up as the worst case scenario for migratory birds, the Altamont Pass wind farm. How does it compare? I did some Googling, and found the following:

From the Heartland Institute:

Giant wind turbines at Altamont Pass, California, are illegally killing more than 1,000 birds of prey each year, according to a lawsuit filed January 12 by the Center for Biological Diversity. The suit demands an injunction halting operation of the turbines until and unless protective measures are taken and highlights increasing concerns regarding a power source long hailed as environmentally friendly by environmental activist groups.

Thousands of wind turbines were built in Northern California's Altamont Pass region during the 1980s in response to activist groups' call for greater reliance on renewable energy sources. Construction of the wind turbines, however, has made the region one of the most deadly places in the world for a large variety of birds. Literally thousands of birds are killed by the turbines each year, including roughly 1,000 annual kills of such valued birds of prey as golden eagles, red-tailed hawks, and burrowing owls.

From the Renewable Energy Law blog:

Contra Costa Times.com reports that an Alameda County (CA) Superior Court Judge has ruled that a lawsuit filed against wind-power companies that operate the Altamont Pass Wind Farm may proceed (registration required).

The lawsuit, which was filed last November by a number of environmental organizations including the Center for Biological Diversity, claims that wind turbines at Altamont have killed 880 to 1,330 golden eagles, hawks, owls and other protected raptors each year for the past 20 years, in violation of California Fish and Game Code provisions as well as the federal Migratory Bird Treaty Act and the Bald Eagle and Golden Eagle Protection Act. The plaintiffs assert that violations of these regulations and statutes amount to unfair business practices and seek damages in order to purchase and preserve bird habitats.

From the Encyclopedia of Earth:

In 1994, shortly after raptor deaths in the Altamont Pass became a general concern, the wind energy industry joined with other stakeholders (government officials, environmental groups, utilities) to form the National Wind Coordinating Committee (NWCC), a multi-stakeholder collaborative aimed at addressing the wind/avian issue and other issues affecting the industry's future. NWCC has sponsored numerous meetings and academic papers to better understand wind energy's wildlife impacts, including updates to the environmental community about the latest wind-related research; events related to the biological significance of wind's impacts; and a wind project permitting handbook.

The National Renewable Energy Laboratory (NREL) produced a report in 2003 that estimated that somewhat more than 1,000 birds were being killed annually by the wind turbines in the pass. One-half of the birds killed are raptors. This is significantly more than that estimated by studies in the 1990s. However, the study also estimated that only 24 golden eagles (Aquila chrysaetos) are killed annually, about one-half of that estimated earlier. The golden eagle is a protected species. Most of the raptors killed are red-tailed hawks (Buteo jamaicensis).

The study also concluded that the mortality rate per turbine is nearly ten times that of the previous estimates. Earlier studies suggested the mortality rate ranged from 0.02 to 0.05 birds killed per turbine per year. The NREL study puts the death rate at 0.19 birds/turbine/year.

A Goverment Accounting Office (GAO) report identified several unique features of the wind resource area at Altamont Pass that contribute to the high number of raptor deaths. First, California was the first area to develop wind power in significant numbers and thus has some of the oldest turbines still in operation in the United States. Older turbines produce less power per turbine, so it took many turbines to produce a certain level of energy; today, newer facilities producing the same amount of energy would have much fewer turbines. For example, Altamont Pass has thousands of wind turbines--many of which are older models--whereas, newer facilities generally have significantly fewer turbines. The sheer number of turbines in Altamont Pass is a major reason for the high number of fatalities in the area.

Secondly, the design of older generation turbines, like those found in Altamont Pass, are more fatal to raptors. Specifically, early turbines were mounted on towers 60 feet to 80 feet in height, while today's turbines are mounted on towers 200 feet to 260 feet in height. The older turbines at Altamont Pass have blades that reach lower to the ground, and thus can be more hazardous to raptors as they swoop down to catch prey. The relative absence of raptor kills at newer facilities with generally taller turbines supports the notion that these turbines are less lethal to raptors. Third, the location of the wind turbine facilities at Altamont Pass may have contributed to the high number of raptor deaths. Studies show that there are a high number of raptors that pass through the area, as well as an abundance of raptor prey at the base of the turbines. In addition, the location of wind turbines on ridge tops and canyons may increase the likelihood that raptors will collide with turbines. One reason why other parts of the country may not be experiencing high levels of raptor mortality is partly because wind developers have used information from Altamont Pass to site new turbines in hopes of avoiding similar situations.

It's interesting that the NREL study puts the rate of bird mortality an order of magnitude lower than the NWCC, at least as cited by the Herald. Perhaps someone misplaced a decimal point somewhere, or perhaps reporting standards or study methodologies can vary that much, I don't know. I do know that I'd consider 50 bird deaths a year - the NREL rate times the number of Kenedy turbines - to be well within my tolerance levels. Frankly, 250 a year wouldn't cause me to lose sleep. PPM says they've done studies. How does their data compare?

Of course, you can't consider this in a vacuum, either. The choice isn't just about dead birds versus not-dead birds, it's about wind energy versus another coal plant as well. Just keep the bigger picture in mind, that's all I'm asking. Link via South Texas Chisme.

Posted by Charles Kuffner on October 10, 2007 to The great state of Texas