Jun 3 - Knight Ridder/Tribune Business News - The Pantagraph, Bloomington, Ill.

A government order to halt wind farm construction across the country drew criticism Friday from a group of Midwestern senators, including Illinois Democrats Dick Durbin and Barack Obama.

The U.S. Department of Defense and the Federal Aviation Administration have issued stop-work orders to several wind farms under construction around the country after concerns were expressed that the massive turbines could interfere with military and national-security radar installations, said Eileen Lainez, a Department of Defense spokeswoman.

She refused to confirm on Thursday if Twin Groves Wind Farm project near Saybrook is among the affected wind farms. Twin Groves developer Horizon Wind Energy announced earlier this week that work at the Saybrook facility has been delayed until late June.

Durbin said Friday in a prepared statement, however, that the decision "already affected Illinois, halting installation of a significant wind facility in Bloomington and two other sites -- in LaSalle County and Lee/Bureau counties."

At the request of Congress, the federal government is studying the effects wind farms could have on radar, Lainez said. She was unsure how long the projects could be delayed as a result of the study.

Six senators from Illinois, Wisconsin and North Dakota sent a letter on Friday to the Defense Department and the FAA expressing concern over the order to halt construction at 12 facilities in those states and South Dakota.

"Windmills have become an important source of clean alternative energy throughout the country," Durbin said in a prepared statement. "This decision … to halt windmill construction is premature and may have serious negative economic effects."

The senators asked for a "swift and thorough assessment" of wind farms' effect on radar installations and a quick resolution if a problem is found, Durbin said in his statement.

The affected wind farms are in direct line of sight for National Air Defense and Department of Homeland Security radar facilities, Durbin's statement said.

Most U.S. land falls in such line of sight, according to Durbin, and more than 20 wind farms in operation or development in Illinois alone are in danger of being shut down.

Twin Groves will have up to 267 turbines churning out enough power for 120,000 homes, making it one of the largest wind farms in the nation.

The wind farm is one of several proposed for Central Illinois, including proposals in the Gibson City area, Hudson, Benson, Delavan and northern Livingston County. Wind farms in LaSalle and Bureau counties already are operational.

Meanwhile, an American Wind Energy Association statement notes the "possibility of radar interference has been known for a long time" with wind farms and that a variety of solutions exist. It noted that turbines are in operation on military sites such as Guantanamo Bay and an Air Force base in Wyoming.