Imagine cutting your electric utility bill and reducing greenhouse gas emissions at the same time.

 

That’s the sales pitch from a group that wants to build the country’s first offshore wind farm on a 28-acre patch of Nantucket Sound called Horseshoe Shoals, nine miles off the Vineyard and just four miles at its nearest point to the Cape.

 

Tuesday evening, the Martha’s Vineyard Commission sponsored an informational session downstairs at the Old Whaling Church in Edgartown where representatives from Cape Wind Associates explained their project and fielded questions and comnrents, nearly all of them positive. More than 20 people attended.

 

Surprisingly, the prospect of 170 wind turbines spread across the sea, 426 feet tall at the tip of their rotor blades and visible from State Beach, provoked little protest on the Vineyard aside from two fishermen and a recreational boater skeptical about the effects of such a large scale project.

 

The project, modeled after offshore wind farms in Scandinavia, will require state and federal review before getting approved. An environmental report is still being prepared and won’t be ready for 10 months.

 

But most Islanders who turned out this week, while curious about the visual impact, were more focused on the environmental benefits that such a project promises.

 

“It is my vision that the Vineyard make a commitment to increasing the use of renewable energy,” said Kate Warner, a member of the Martha’s Vineyard Commision and the West Tisbury representative to the Cape Light Compact, an association of 21 Cape and Island towns advocating lower energy costs and conservation measures.

 

Ms. Warner, more than just introducing the main speakers for the evening, framed the wind farm proposal in terms that went beyond the price of electricity.

 

“With the effects of global warming and the trend toward more extreme weather,” she said, “parts of the Island may be underwater.” The key, according to Ms. Warner and the Cape Wind advocates, is to reduce greenhouse gas emissions created in large part by power plants burning coal, gas and oil.

 

Wind-powered turbines, by contrast, could produce electricity in breezes as light as seven to eight miles an hour. At 25 miles per hour, the wind could generate an average of 170 megawatts a day, or 420 megawatts at peak production. Peak demand on the Cape and Islands is about 440 megawatts in the summer, according to the Cape Wind figures presented Tuesday.

 

Sponsors of the project said Horseshoe Shoals is the ideal location, chosen for its shallow water - 12 to 50 feet in depth - its favorable wind conditions and its proximity to the Cape Cod power grid.

 

The $500 million to $700 million project would be bankrolled by private interests which include Energy Management Inc:, a Boston group that has developed other power projects; Wind Management LLC, based in Yarmouth, and Environmental Science Services Inc., a Wellesley consulting firm.

 

“This is the right project at the right time in the right place,” said Craig Olmsted, vice president of projects at Cape Wind.

 

In simulated photographs, meant to show how the wind farm would appear from the shores of the Vineyard, the turbines were barely visible on the horizon. Donald Sibley of West Tisbury raised his hand to say he admired the sculptural beauty of the turbines.

 

“I would suggest you have a photograph that makes them as visible as can be,” he said.

 

“And don’t paint them to blend in,” said Linda Sibley, a member of the Martha’s Vineyard Commission. “Make ‘em honest. Paint them white.”

 

Mr. Olmsted said that in Europe, offshore wind farms are actually tourist attractions. John Abrams of West Tisbury offered a story to illustrate how people’s initial reluctance can turn into admiration.

 

“In 1978 when we put up a wind generator at Allen Farm, townspeople were not very happy,” he said. “But there were more complaints when we took it down. People had grown to love it. They’re beautiful to look at.”

 

But aside from aesthetics, there were questions about how 170 turbines spread at one-third to half-mile intervals would affect navigation and marine life. Mr. Olmsted pointed out that the wind farm would be sited outside shipping channels, ferry routes and flight paths.

 

But the turbines would be smack in the middle of rich fishing grounds, said Chilmark fisherman Chris Murphy, who waited until late in the session before striding to the front of the room.

 

“That’s where the fish grow up, a natural, wonderful habitat for all sorts of wonderful stuff,” he said. “It’s one of the world’s great natural grow-out areas. The idea of putting anything on them seems bizarre to me.”

Mr. Murphy urged Islanders and Cape residents to demand that the project be reviewed by both the Martha’s Vineyard Commission and the Cape Cod Commission. Currently, the wind farm will be subject to review by state environmental agencies and the Army Corps of Engineers.

 

Mr. Olmsted said that while the impact on fish is unknown, it could be positive. Offshore drilling rigs and turbines have acted as “fish aggregators” elsewhere, he said.

 

Tom Zinno of Oak Bluffs questioned the durability of the turbines, their visual impact and the effect on recreational boating. “These things are monstrous,” he said. “On any given day, there are thousands of boats in that area.”

 

Others questioned how the proposed wind farm might realize savings on electric bills. Mr. Olmsted conceded he had no simple answer to that question. While holding out hope that their cheap source of energy would drive down prices across the region, he said that energy pricing is “very complicated.”

 

George Schiffer of Tisbury asked whether Cape Wind had considered No-man’s Land as a site for their operation. Mr. Olmsted said his group had looked at the area but the presence of unexploded ordnance “makes pile driving an adventure.”