Growing interest in wind power has led to six new wind farms proposed in Vermont and at least five under discussion or construction in New Hampshire. In Maine, at least two projects are facing reviews.

Tod Wicker of the Public Service Company of New Hampshire, the state’s largest electric utility, pointed to four 1.5-megawatt turbines being built in Berlin, a 12- to 13-turbine project moving along in Lempster and three other sites collecting wind data for future projects.

“There could probably be another half-dozen” sites that developers are seriously investigating, Wicker said.

In neighboring Maine, a Canadian company wants to erect 200 wind turbines – each more than 300 feet tall – on the mountains in the west of the state. TransCanada is seeking state approval for the wind farm, which would generate enough power for 70,000 households.

In northern Maine, Evergreen Wind Power LLC hopes to erect 30 wind turbines on Mars Hill Mountain. Linekin Bay Energy Co. LLC of Freeport also is installing six test towers in the St. John Valley to collect wind data before deciding whether to proceed with its own plans for a wind farm in northern Aroostook.

So far, New Hampshire’s projects are small. That’s because wind farms generating anything under 30 megawatts don’t require state review. Those with higher outputs must go before the state’s Facilities Site Evaluation Committee.

New Hampshire has no existing commercial wind farms. By contrast, Vermont already has more turbines than any other New England state with its Searsburg project.

Searsburg, which dates back to 1997, has 11 turbines located on a ridge line next to the Green Mountain National Forest. The company involved, the Deerfield Wind Project, wants to expand by 20 to 30 more turbines in Searsburg and Readsboro.

Combined with projects elsewhere in the state, Vermont could be looking at another 135 turbines if all are built.

“It’s probably not going to be many more than that because the amount of suitable land is going to be so limited,” said John Zimmerman of Vermont Environmental Research Associates, a Waterbury company overseeing two proposed Vermont wind farms.

Only a fraction of the state’s ridges, about 5 percent to 7 percent, are suitable for wind generation, Zimmerman said. Required heights and access to power lines limit where turbines can go.

They remain controversial, however, with opponents objecting to cluttering up scenic ridges and endangering birds.