Supporters say the so-called wind farm would cut pollution while easing global warming and the nation's reliance on foreign oil.

Opponents argue the project would hurt sea birds, scenic views and tourism, the cape's key economic engine.

Wind power is the fastest-growing commercial energy source in the world. Wind farms already dot the countryside in nearly 30 U.S. states, Europe and Australia. Denmark, among the biggest European users of wind-generated electricity, has one of the world's most successful offshore wind farms.

In many states, new laws require utilities to increase their use of renewable energy. In Massachusetts, a law taking effect next year requires that by 2009, the state must produce enough renewable power to light about 100,000 homes. Other New England states have similar requirements.

ENVIRONMENTAL CONCERNS

The need for clean power in New England, where strong sea breezes are common and dense population concentrations are coupled with an older electricity grid, would seem to make wind power an easy sell.

But some residents and environmental groups argue the turbines would mar Cape Cod's pristine oceanscapes by planting a forest of enormous towers in plain site. They say the project would damage tourism, wreck commercial and weekend fishing and put boaters and recreational flyers at risk.

"We feel this is going to endanger the environment and hurt both sea birds and mammals," said Isaac Rosen, of the Alliance to Protect Nantucket Sound. "We fear there will be a deleterious effect on tourism, which is the backbone of the cape's economy."

The project has drawn ardent support from clean energy advocates and others who say the wind farm, which would produce about half the electricity needed by Cape Cod and the nearby islands of Martha's Vineyard and Nantucket on an average day, would combat global warming, ease pollution and lessen the country's need for imported oil.

"We believe the public benefits of this project are going to far outweigh the negatives," said James Gordon who heads Cape Wind Associates LLC, the project's backers.

Opponents suffered a legal setback in early October when a federal judge threw out a lawsuit that tried to block Cape Wind from building a data communications tower.

The judge declined to issue an injunction, ruling the opponents had no legal standing, would not suffer irreparable harm if the tower went up and were not likely to succeed at trial on the merits of their case.

Gordon called the decision "an important victory" and said the firm would start work on the data tower within days. It was expected to begin operating before the end of November.

While the wind farm still faces another federal lawsuit and must complete extensive permitting, the judge's decision gave the project a big boost.

170 40-STORY TOWERS

The farm would be comprised of 170 giant wind turbines anchored in the shallow waters of Horseshoe Shoals, about six miles (10 km) from Hyannis, Massachusetts, and nine miles (15 km) from the Vineyard. The turbines, which would be about 40 stories tall, would be spaced six to nine football fields apart over 28 square miles (73 square km).

The wind turns the turbines, which power a generator in the turbine hub, which generates electricity.

At peak output, the wind farm would generate 420 megawatts of power, enough to satisfy nearly the entire 440 megawatts the cape uses on peak demand days, Gordon said. Average demand is about 350 megawatts and Cape Wind's average output of 170 megawatts would satisfy about half of that need.

The electrical output would replace the equivalent of 113 million gallons (429 million litres) of oil or 500,000 tons of coal a year.