SOUTH PORTLAND — Larger rotors, taller towers and other technical refinements in turbine design have unlocked substantial new wind power potential in New England, a research scientist told participants at a packed conference on Wednesday.

The trend toward “turbine scaling” means wind power can make economic sense at lower elevations and in places that don’t have the highest wind speeds, said Mark Bolinger of the Lawrence Berkeley National Laboratory.

New England has many such sites, he said, such as the rolling hills near Eastbrook, in Hancock County, where Boston-based First Wind is building a 19-turbine project called Bull Hill.

Bolinger spoke during the first day of the American Wind Energy Association’s regional summit, which drew about 400 people to the Portland Marriott at Sable Oaks.

His optimistic outlook on demand in New England offered good news for developers and manufacturers who are jittery about the future of tax credits that are crucial to their industry, and are set to expire this year unless Congress extends them. New projects and thousands of jobs that go with them depend on the extension, an association official said.

However, the ability to build wind projects on lower terrain isn’t a welcome development for everyone.

Brad Blake, a spokesman for the Citizens Task Force on Wind Power, said most of Maine has marginal wind potential, and the technical improvements that Bolinger touted will create more conflicts with people who oppose industrial wind power development.

The towers at Bull Hill, he said, are 476 feet tall and visible from Cadillac Mountain in Acadia National Park.

“We shouldn’t have to sacrifice the mountains of Maine so the industry can squeeze a little more output from their monstrous machines,” Blake said.

With its largely forested landscape and hilly terrain, Maine dominates New England’s wind-energy potential. Nineteen projects are completed or in development, and the state will have 400 megawatts of installed capacity by year’s end. The potential is even greater offshore, where a pilot project involving floating turbines is being considered.

Lighter and stronger materials are allowing turbine manufacturers to build larger units that create more power, Bolinger said. The average diameter of rotors in New England has grown from roughly 262 feet in 2008 to 328 feet this year, according to data he compiled. The larger diameters can boost turbine capacity from around 2 megawatts to 2.5 megawatts.

Such incremental developments are important to the industry because, on an annual basis, unsteady wind speeds limit turbine output to less than 35 percent of its “nameplate” capacity.

In an interview, Bolinger said it’s not likely that manufacturers can improve performance over the next few years at the same pace.

Over the next few months, much of the industry’s attention will be focused on Washington and the future of production tax credits. The 20-year-old provisions are tied to electricity output and meant to encourage development of renewable-energy projects, but they have come under fire in a political climate in which all taxes are under scrutiny.

Rob Gramlich, the association’s senior vice president for public policy, said the industry is lobbying Congress with this message: The tax breaks won’t be needed forever but are vital now to save 37,000 jobs. To finance projects and lock down permits, developers need 18 months of certainty on taxes, he said.

That message is getting through, Gramlich said. Last month, the Senate’s Finance Committee passed a package to extend the credit and a related provision for projects that start construction by the end of 2013. The industry’s hope now is that, after the election Nov. 6, a lame-duck Congress will extend the credit as part of a broad package of tax issues.

In their criticism of wind power, Blake and other opponents say the wind industry wouldn’t be profitable without government tax breaks. However, Dave Wilby, vice president for state policy with First Wind, said the production tax credit was created to let renewable energy compete with coal, oil and natural gas generators, which have enjoyed various tax breaks for decades.

“The energy industry exists only because of government policies,” Wilby said. “There’s this fiction that there’s a free market in the energy business.”

The summit continued Thursday, concluding with a presentation on offshore development in the Northeast.

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.