LEMPSTER, N.H. – Construction on New Hampshire’s first commercial wind farm project is expected to begin by the end of the summer now that the developer has received final state approval.

After three years of planning and permitting, developer Iberdrola received the last of the required state approvals this month. The company hopes to begin producing electricity sometime next year, said project manager Ed Cherian.

When the project is complete, a dozen 400-foot-tall turbines will stand along the Lempster Mountain ridgeline, generating enough electricity in a year to power roughly 10,500 homes.

Though rugged terrain and limited open space has slowed wind power development in New England, the industry is growing, Cherian said.

“The U.S. has a lot of wind, and it’s one of the resources we’re starting to take advantage of,” he said. “There is no wind OPEC. No one owns it. It’s free and it’s clean.”

Iberdrola wants to build more wind farms in New Hampshire and surrounding states, and at least one other company has said it is looking to develop a wind project in Coos County.

In Maine and Vermont, commercial wind farms have been built in the past two years and several others are in the early planning stages. In Massachusetts, the federal government said last month it will give the state as much as $2 million to test wind turbine technology.

“What’s happening in New Hampshire fits the national trend,” said Tom Welch, a spokesman for the U.S. Department of Energy’s wind and hydropower technologies program.

Commercial wind projects have been built in 27 states. But even with the growth of the wind sector, the amount of electrify generated from renewable sources remains small.

Less than 10 percent of all power generated in the United States comes from wind, water and solar energy, according to the Energy Information Institute, a government agency that keeps statistics for the energy department.

The traditional challenge for wind developers in New England has been finding the right place to put the turbines, Cherian said. The wind has to prove steady and be unobstructed by trees and mountains.

Another challenge has been local opposition to the projects from residents worried about safety, noise and visual pollution.

In Lempster, about 100 people with concerns about the project appealed to the state last year for additional oversight of the project. Lempster Board of Selectmen Chairman Everett Thurber said he was satisfied by the review.

“The state has been extremely thorough,” he said. “There is overwhelming support for the wind project in Lempster. We see it as benefiting our town.”

The Lempster project will be the first project in New England for Iberdrola, which is based in Spain. It has hundreds of other projects under development across the United States.