Plans for the world's largest wind farm, proposed to be built in South Dakota, have become more grandiose.

South Dakota is officially rated No. 4 in the nation for the potential capacity to make electricity from wind, although the ranking is more than a decade old. Many industry officials believe the Great Plains state is the windiest of all.

Clipper Windpower of Carpinteria, Calif., intends to erect enough wind turbines in several South Dakota counties to produce up to 6,000 megawatts of electricity, said Bob Gates, the firm's senior vice president of commercial operations.

That would be eight times larger than the biggest wind farm in the world, a 735-megawatt FPL Energy facility with 421 turbines stretching across three Texas counties.

Clipper Chairman and Chief Executive Officer James Dehlsen told The Associated Press in 2004 the company intended to develop a $3 billion wind complex with 1,000 turbines that could produce 3,000 megawatts of juice in South Dakota.

But as envisioned now, the project would be twice as large and cost $6 billion, Gates said.

Taking into account that the wind doesn't always blow or is too light or strong at times to operate turbines, a 6,000-megawatt wind farm could supply enough power for an average of about 1.6 million homes, based on data from the American Wind Energy Association.

Clipper makes 2.5 megawatt turbines, and it would take 2,400 of them to produce 6,000 megawatts of electricity. However, the firm continues to develop more efficient turbines and is part of a project to build 7.5 megawatt turbines for an oceanic wind farm off the coast of Britain.

Clipper officials are not saying exactly where the proposed mega complex will be located in South Dakota, but they indicate it will be built in stages.

"I think each stage would eclipse the size of the previous one," Gates said.

If Clipper can find a buyer for the electricity, the project could get under way in a couple of years, he said.

Huge amounts of extra electricity cannot be moved out of South Dakota until more transmission lines are developed, however.

"To do big-time wind, you need to put in upgraded and new transmission capabilities," Gates said.

Gates, president of the American Wind Energy Association, met recently with Sen. John Thune, R-S.D., about the future of wind development in the nation.

Thune hopes an energy bill pending in Congress will extend a federal tax credit for the wind industry. The incentive of 1.9 cents per kilowatt hour, initially approved in 1992, is to expire at the end of the year. It typically has been extended by only a year or two, but Thune said Congress should either make it permanent or extend it for four or five years at a time.

The Department of Energy said the nation's wind-power capacity increased by 27 percent last year, but wind farms operating in 36 states account for less than 1 percent of the U.S. power supply.

The American Wind Energy Association believes 20 percent of the nation's power could come from wind someday.

According to the association, Texas leads the nation in wind power, followed by California, Iowa, Minnesota and Washington.

Many companies are interested in building wind farms, and South Dakota stands to land several of them if the tax credit is extended and the transmission bottleneck can be fixed, he said.

"They know that we have an unlimited resource," Thune said. "South Dakota is the windiest state in the nation. The National Renewable Energy Laboratory has estimated that South Dakota has enough wind potential to provide 55 percent of all the electrical needs in the country."

NREL says South Dakota has good to excellent wind resources consistent with utility-scale electrical production. It specifically points to hills east of Pierre, ridges along the eastern and northeastern border, hills in south-central South Dakota near the Nebraska border and many mountain crests in the Black Hills.

The energy bill, which has passed both the House and Senate and is awaiting congressional negotiations on differences, includes an amendment from Thune that would promote the establishment of special corridors to move wind-produced electricity from its source to high-demand population areas.

"It would create an interstate highway for wind," the senator explained. "Right now, we've got a transmission system that makes it difficult to get electricity from one area of the country to another. We need a corridor where you can easily move energy anywhere."

Cumbersome and complex regulations and many fees now govern the movement of electricity, Gates said. Wind energy will be hampered unless the system is streamlined and transmission capacity is substantially increased, he said.

"We've got to build electrical transmission lines to bring the energy from where it's windy, largely in the Great Plains, to where the people are," the Clipper official said.

"This nation can make this happen if we merely choose to do so," he added.

The most efficient wind farm in the nation is located near Highmore, about 60 miles east of Pierre, Thune said. That FPL facility has 27 turbines and generates 40 megawatts of electricity.

"I think the sky is the limit for South Dakota when it comes to wind energy development and production and job creation," Thune said. "There's a tremendous upside here that hasn't been tapped. We've got the wind, and there are folks who want to develop it."