WASHINGTON – Proponents of the Cape Wind project on Nantucket Sound say wind farms like it will help wean the country from dependence on foreign oil. Opponents suggest it will harm the area’s environment, scenic views and economy. And both sides insist wealthy interests are doing their best to manipulate the decision-making process by hiring high-priced lobbyists and cutting backroom deals on Capitol Hill.

The fight over Cape Wind – a 130-turbine wind farm that would span 24 square miles of federal water off the Massachusetts coast – highlights how development of alternative energy remains a complex and often contentious business.

After years of failed plans and minimal growth, the nation’s installed wind capacity grew 35 percent last year. Texas officials recently approved the nation’s largest offshore wind farm – which, when built, will be able to power 125,000 homes. One wind farm is operating in West Virginia, with more applications pending in that state as well as in Maryland and Virginia. But small communities in Vermont, Massachusetts and elsewhere have fought stubbornly to block wind farms, and some operators are struggling with a shortage of turbines and the challenge of transmitting wind-generated electricity to more populated areas.

Wind proposals are under consideration in several Maine locations.

“The wind industry is not in a mature phase in the U.S., but it has a good future,” said Michael Liebreich, who heads London-based New Energy Finance, which analyzes clean energy projects.

“It’s part of the answer” to the energy crisis, he added, but “we’re not going to get rid of oil and coal and nuclear power in the next 20 years.”

For the moment, projects such as Cape Wind often still face formidable obstacles. Last month, Sen. Ted Stevens, R-Alaska, inserted language in a Coast Guard reauthorization bill to allow Massachusetts Republican Gov. Mitt Romney to kill the project, a move Stevens and Sen. Edward Kennedy, D-Mass., defended.

Kennedy, whose family’s famed compound in Hyannisport looks out on Nantucket Sound, has led the fight against Cape Wind. He said he opposes the venture on policy rather than personal grounds.

“That is a giveaway of public land that belongs to the country,” he said in an interview, noting there was no competitive bidding on the wind farm and the developer would reap tens of millions in federally funded tax credits for renewable energy. “Those credits are coming from working families.”