Those conclusions come from radar engineers hired by the Federal Aviation Administration to examine what effects Chugach's proposed wind farm would have on the airport. The FAA runs the nation's air traffic systems, including radars and control towers at airports.

A Chugach Electric Association official said the company has already modified its concept so that the windmills won't block the Fire Island radar, a navigational beacon known in pilot-speak as a "VOR."

But electromagnetic problems remain between the wind project and the airport's primary air traffic control radar.

Anchorage-based Chugach is the state's largest power utility, with customers from Homer to Fairbanks. It has toyed with using wind power for years as a way to bring less-polluting, non-fuel-using electricity generation to the state's Railbelt region. It has studied costs, demand and the best locations for windmills.

About a thousand VOR radars are spread across North America as navigational beacons. Virtually all planes flying near Anchorage use the Fire Island VOR, from private Cessnas landing at Merrill Field to Elmendorf's fighters to airliners passing five miles overhead. VOR radars need clear lines of sight in all directions, down to a specific angle from the ground.

Phil Steyer, a Chugach manager closely involved with the project, said that to accommodate the VOR, "we've done some turbine reallocations, some went away and some added with height limitations."

Chugach is partners in the wind-power initiative with three other utilities: Anchorage's Municipal Light & Power, Homer Electric Association and Golden Valley Electric Association in Fairbanks.

The original concept was for 33 windmills on Fire Island generating up to 3 megawatts each, which in peak conditions could hit 100 megawatts of power, about a fifth of the energy Anchorage can demand. A 3-megawatt windmill stands 265 feet tall, with blades almost 150 feet long. But to fit around the VOR, Steyer said, the utility scaled down the idea to two dozen 1.5-megawatt windmills, cutting the project's possible output.

"That still leaves issues with the approach radar," Steyer said.

Air traffic controllers use an "approach" radar to guide planes arriving at and departing from the airport.

As a modern windmill spins in a breeze, its blades turn an electric turbine, which uses an electromagnetic field to create electricity. That field, if large enough, can radiate for miles and disrupt radio transmissions of all kinds.

According to the FAA's engineers, even Chugach's smaller windmills could produce electromagnetic fields that cause "false target presentations and permanent echoes on air traffic control radar displays."

In other words, controllers in the airport's control tower might see planes where there were none or be blind to real ones.

Officials with both the FAA and Chugach said they are continuing to work together on the problem, though it's unclear what, if anything, can be done. FAA spokesman Allan Kenitzer said the agency is "assessing methods of modifying the radar to avoid any adverse effects" to airport operations but would not be more specific. He also would not say whether Chugach's revised concept would alleviate concerns with the Fire Island VOR.

The idea of using Anchorage's natural wind tunnel, otherwise known as Turnagain Arm, to generate electricity is not new, nor is this the first time Chugach Electric's hopes for developing wind power have hit, well, turbulence.

"We have been looking at the potential for wind generation around Southcentral Alaska since at least 1998," said Steyer. "It's all dependent upon economics of the project. No decisions have been made whether to try and bring the process forward."

Chugach declared Fire Island a favorite spot for a wind farm in 2004, after several years of studying possible sites around the region.

A site near Whittier was deemed too windy and likely to damage the machines. One at Bird Point on the Seward Highway was too small. The Army declared military land near Arctic Valley off limits. And the wind at a site above Bear Valley was too icy.

And projects at any of those sites, officials said at the time, would have been scorned as eyesores.

But Fire Island has plenty of windy real estate owned by Cook Inlet Regional Inc., the Anchorage regional Native corporation, which signed on to the project. And three miles from the nearest scenic overlook, the site was less likely to draw aesthetic complaints.

On the downside, construction on the island would be more costly than on a mainland site, said Steyer, and power cables would need to run underwater to the mainland.

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Daily News reporter Matt White can be reached at mwhite@adn.com or 257-4350.