Cape Wind is Cleared for Takeoff — Mostly

Cape Wind, the wind farm proposed for a 24-square-mile tract of Nantucket Sound off Cape Cod, Mass., got its final government permit on Friday, 10 years after work on the project began, the sponsors announced. They hope to begin construction this year, although they have not yet lined up a market for all of the electricity.

Many proposals have emerged for offshore wind farms, but Cape Wind is the first to have all its permits, the sponsors say. The last two were issued on Thursday and Friday, by the Army Corps of Engineers and the Environmental Protection Agency. The Interior Secretary, Ken Salazar, promised last April that the approvals would be forthcoming.

The next hurdle appears to be selling the power. Last May, Cape Wind announced it had a deal to sell half the electricity to National Grid for a price beginning at 20.7 cents per kilowatt-hour, approaching double the national average retail rate. Massachusetts state regulators turned that down, but in November the state accepted a contract with National Grid at a price beginning at 18.7 cents a kilowatt-hour.

While the price is still high above average, there is some hope that Cape Wind would deliver electricity during peak demand periods, when all prices are high. In fact, by dumping more energy into the market during peak periods, it could drive down the prices established in New England’s daily power auctions.

Mark Rodgers, a spokesman for Cape Wind, said that the company was negotiating with several utilities to sell the other half of the output and could not get loans to build the whole project until more of it is purchased. But “there’s a lot of scenarios,” he said. “We’re confident the project will move ahead.”

One option is to start work promptly on the portion for which power has been sold. The whole project is supposed to comprise 130 turbines, each rising 440 feet.

But the company’s cost estimates are based on building the whole project, whose cost is likely to exceed $1 billion. Advocates of offshore wind say prices will decline as a shore-side industry develops, to manufacture parts and serve the ships that do the work off the coast.

The first phase of construction will be for electricity transmission, he said, and will begin in 2011.