Altamont Pass Report Encourages Wind Farm Changes

Sacramento, California - August 17, 2004 [SolarAccess.com] Bird deaths caused by wind turbines at Altamont Pass Wind Resource Area in California helped contribute to a chain reaction of worries across the nation about how wind power effects bird species. After four-years of study to address the effects of wind turbines on bird mortality, the California Energy Commission (CEC) has released a report that details their findings and could be a guide to wind farms across the country.

According to research data, an estimated 1,766 to 4,721 birds, of which 881 to 1300 are protected raptors, are killed annually at Altamont Pass. Researchers studied bird behaviors, raptor prey species availability, wind turbine and tower design and location, landscape attributes, and range management practices to try and explain the variation in bird mortality. The goal was to develop models that could be used to predict high collision-risk situations and site new turbines in lowest risk locations.

Measures identified in the commission's report to reduce bird deaths include: relocating selected, highly dangerous turbines; removing broken and non-operating turbines; installing structures at the ends of turbine strings to divert birds around the turbines and blades; and rodent management practices - other than poisoning - to control food source populations that congregate around the base of turbines. If successfully put in place throughout the Altamont Pass area, these measures may reduce bird mortality by up to 50 percent for some species.

"This finding echoes the recommendations of other researchers who have studied Altamont Pass extensively over the past decade," said Tom Gray, the communications director of American Wind Energy Association. "Wind energy companies with projects in the pass have been engaged for some time with local, state, and federal agencies in an intensive effort to understand the causes of raptor collisions with wind turbines and to identify ways to reduce them, and we expect that effort to continue."

To compensate for continuing and unavoidable losses, CEC researchers also recommended securing habitat to protect affected bird species for the long term. In addition, the new turbines and any new mitigation measures implemented should be monitored for at least three years to determine if they result in a reduction in bird mortality.

There's heightened urgency to resolve the environmental concerns, according to the report. California's goal of producing 20 percent of its electricity from renewable sources, including wind, by 2010 could be hindered without the harnessing of wind power available in Altamont Pass. Alameda County will not allow permits to increase electrical production at Altamont beyond the existing capacity of 584 MW until there is demonstrated progress toward reducing bird kills.

The perception among the some of the general public that wind farms can harm birds has been partially cultivated by these findings at Altamont pass -- and wind power foes often use this example to characterize all wind farms as having the same potential for conflict.

"It's important to make clear that the highly publicized problem in Altamont Pass is not representative of wind farms across the U.S.," Gray said. "Wind farms do coexist successfully with wildlife in many other locations."

Overall, wind turbines in California have an installed generating capacity of 2,000 MW, including a potential of 800 MW of energy generated at Altamont Pass. Wind turbines provide up to 3.5 billion kWh annually of emissions-free electricity in California. Some wind operators in the Altamont Pass had applied for re-powering permits in 1998, but never completed the process partially because of the bird mortalities. Implementing new methods and technologies to reduce the collisions in Altamont Pass will help producers increase wind electricity yield at the site, and effective measures could be applied as mortality-reduction methods at other sites around the state and country.

Some turbines in the Altamont Pass area are an old design that relies on a lattice style tower for height, which look similar to towers used for high-tension wires. As opposed to the new, larger tower designs, the older lattice style towers offer birds many places to perch - putting them in danger of the spinning blades. New towers and vertical and smooth, preventing this possibility.

Researchers also found that turbines at the end of turbine rows, on either end of a gap in the row, in deep canyons, and in isolation caused disproportionately more collisions than other turbines. However, birds that would perch on turbines and horizontal towers were less of a factor than previously suspected.

These and other findings led the researchers to conclude that the most effective solution to reducing bird collisions in the Altamont Pass area is to replace the numerous small existing turbines with fewer, larger turbines on taller towers. The newer turbines are much more efficient, with one turbine generating the same capacity as seven to 10 older ones, thus allowing for more generation and fewer opportunities for collision.

The Altamont study was funded by the commission's Public Interest Energy Research (PIER) program, and conducted by BioResource Consultants from Ojai, California.

A link to the commission's 502 page report is supplied below. There is an executive summary on the same page as the report download. It is recommended to read the summary first and download the report only if necessary. It's a large file and will easily slow down a system that doesn't have adequate memory or processing speed.