A decision to block wind energy development from key sage grouse habitats in Wyoming could effectively nullify a significant portion of the state's wind energy resource. But exactly how much is unclear.

The U.S. Fish and Wildlife Service is considering listing the sage grouse as a threatened and endangered species. Half of the bird's remaining prime habitat in the West lies within Wyoming's borders. Last year, Gov. Dave Freudenthal issued an executive order prescribing grouse "core areas" in the state where activities are subject to special restrictions.

Freudenthal's energy infrastructure adviser, Aaron Clark, noted that less than 14 percent of Wyoming's best wind resources fall within the prescribed core areas. He was responding to one wind energy industry official's early estimate that blocking wind development on the core areas would take 75 percent of the state's best wind resources off the table.

According to Clark, Wyoming's sage grouse core areas overlie 25 percent of the state's Class 4 wind (good) resource, 25.2 percent of Class 5 (excellent), 18.1 percent Class 6 (outstanding), and 5.3 percent Class 7 (superb).

However, a wind industry official said the statistics, based on a wind resource map by the U.S. Department of Energy, doesn't take into account the fact that some of those wind resources are not considered developable.

Nate Sandvig, project manager for Horizon Wind Energy, said developers must focus on wind resources that are close to existing electrical transmission lines, for example. Numerous setback requirements and opposition to wind development in some regions further reduce viable wind resources.

That means blocking wind turbines from core areas has a bigger impact than might be surmised by overlaying the two resource maps. Sandvig said the industry effectively stands to lose a significant portion of low-hanging fruit, including Horizon Wind Energy's proposed Simpson Ridge project in Carbon County.

"The big concern is, with some of the best wind project sites located in core areas and the location of planned transmission through these core areas, the goals for renewable energy in the West are in jeopardy," Sandvig said.

Sandvig estimates that the sage grouse core areas overlie 28.5 percent -- nearly 1.5 million acres -- of areas with viable annual wind speeds for commercial development.

In response to the state's core areas decision, a coalition of wind developers has teamed up with wildlife agencies across nine Western states to launch a $10 million, five-year research effort.

The coalition hopes to gather scientific data needed to understand the impact of wind farms on sage grouse so that the industry might configure wind facilities in ways that avoid impacts.