As the year began, Michael Polsky was poised to plant wind farms in the fields of Wisconsin, Illinois, and South Dakota that would power some 3,000 homes. But in March, the CEO of Invenergy received a letter from the Federal Aviation Administration saying the projects could disrupt the radar signals of nearby military installations.

The letter recommended he delay the projects pending results of a Defense Department study. Polsky was stunned, but he's complying. As many as 12 other proposed wind farms received similar warnings. "I can't imagine how turbines located 12 to 40 miles away can interfere with radar," Polsky says.

Plenty of other wind-energy producers are baffled, too. With President Bush pushing for alternative energy and with generous tax credits in place, 2006 was supposed to be a banner year for wind power. Instead, experts say, the industry is faltering while it awaits the results of the study mandated in this year's defense authorization bill by Sen. John Warner, chairman of the Armed Services Committee.

Wind turbines, which can reach 400 feet high, have cluttered radar signals in the United Kingdom, where wind power is more prevalent. Experts say that while older American systems are susceptible to similar problems, they can be fixed by hardware and software upgrades. Warner says an analysis of the problems is necessary to answer questions about radar interference. But critics decry the study as a political maneuver aimed at derailing one project in particular: Cape Wind, a proposed farm of 130 turbines off the shores of Cape Cod. "What we're seeing here," says Jerry Taylor of the Cato Institute, a libertarian think tank, "is the NIMBY phenomenon playing out against green technology." The result is a Washington maelstrom that has jumbled party alliances and left the future of wind power in limbo.

Slated to cover 24 square miles of federally controlled waters in Nantucket Sound, Cape Wind would be the nation's first offshore wind farm and could supply up to 75 percent of the electricity needed by Cape Cod and nearby islands. However, powerful opponents, including Massachusetts Sen. Ted Kennedy, who lives on the cape, say the project will destroy vistas while harming the environment and the fishing industry. Cape Wind also presents a danger to sea and air vessels, Kennedy says. Cape Wind opponents have spent at least $1 million since 2002 on Washington lobbyists fighting the project. Sen. Ted Stevens of Alaska, along with Kennedy, proposed giving veto authority over the project to Massachusetts Gov. Mitt Romney, another Cape Wind foe. The language was removed in June after bipartisan protests from leadership on the Senate Energy Committee.

Home field? Critics have also noted that Warner's two daughters own properties in the Cape Cod area. John Ullyot, a spokesman for Warner, says the senator wants "only that we get all the facts together so that we can understand the impact [of wind turbines] on military radar." It wasn't Warner's idea to recommend that the wind farms in question be delayed until the study is completed, says Ullyot; that's just Pentagon policy.

Approving wind farms is ultimately up to the FAA, which regulates the country's airspace, but the FAA seeks the Pentagon's input in making its decisions. Even so, FAA spokesperson Laura Brown denies that the study is responsible for the chill that has settled over the wind industry; she attributes the delay instead to a dramatic increase in wind-farm applications. But the letters received from the FAA by Polsky and some of the other applicants seem to cast doubt on that claim; those letters say wind farms within a radar's line of sight should be delayed until the study is finished.

Supposed to be completed in May, the study is still ongoing. Last week, Illinois Sens. Dick Durbin and Barack Obama promised to block a nominee to a top FAA post until the report is completed. "The FAA and the Defense Department need to get it together," says Durbin, who admits he's suspicious of the motives behind the study.

Some affected projects are now moving forward, but exasperated developers say the bottom line is simple. As a practical matter, they cannot proceed until they know the results of the Defense Department study, which could recommend that parts of the country, including offshore sites, be restricted for the sake of national security. "You can call it politics ... or you can call it guilty by association," Polsky says. "What's bothering us is that we don't have a resolution." Call it Washington wind power.