Although offshore wind farms are roughly twice as expensive as land-based ones, developers and advocates say offshore projects have several advantages. Sea and lake breezes are typically stronger, steadier and more reliable than wind on land. Offshore turbines can also be located close to the power-hungry populations along the coasts, eliminating the need for new overland transmission lines. And if the turbines are built far enough from shore, they do not significantly alter the view — a major objection from many local opponents.
The National Renewable Energy Laboratory has estimated that about 90,000 megawatts of electricity could be extracted from offshore winds in United States coastal waters less than 100 feet deep, the easiest and most cost-effective depths. Most of that potential lies in New England, the mid-Atlantic and the Great Lakes.
If the handful of American projects on the drawing board are built as planned, they would produce some 2,500 megawatts, according to the American Wind Energy Association, or about as much as two midsize nuclear power plants.
The Cape Wind project would place 130 turbines, each 440 feet tall, over 24 square miles of Nantucket Sound at a likely cost of more than $1 billion.
Opponents have argued that the venture is too expensive and would interfere with local fishermen, intrude on the sacred rituals and submerged burial grounds of two local Indian tribes and destroy the view.
“Cape Wind’s oversized costs do not represent a reasonable return on the public’s investment,” wrote Joseph P. Kennedy II, the former congressman and president of the Citizens Energy Corporation, a Boston nonprofit group, in a letter to The Cape Cod Times in February. Mr. Kennedy’s family owns property that looks out on the proposed wind farm site.
“Citizens Energy has been involved in alternative energy development for decades,” Mr. Kennedy continued, “but we do not include in our business model a plan to pick the public’s pocket.”
But proponents of the project, which include major environmental organizations like the Sierra Club and Greenpeace, point to a February study by Charles River Associates, a consulting firm hired by Cape Wind’s developers, suggesting that the project could save New England ratepayers $4.6 billion in energy costs over 25 years. They also say that the project has undergone two separate environmental impact analyses, neither of which found significant downsides.
The governors of six East Coast states — Delaware, Maryland, Massachusetts, New Jersey, New York and Rhode Island — last week called on Mr. Salazar to approve the project.
But even if Mr. Salazar gave the approval, opponents of Cape Wind would probably continue to challenge it in court and the company would still need to strike a deal with a utility to buy the power.
Jim Gordon, president of Energy Management, the firm heading the Cape Wind project, is weary but resigned. “It’s hard whenever you’re a pioneer trying to do a first of a kind,” he said. “We always recognized that this would not be an easy path.”
Despite Cape Wind’s struggles, a small but determined wind industry has emerged elsewhere, proposing several ocean projects off the shores of New Jersey, Delaware and Rhode Island, as well as freshwater projects in the Great Lakes near Cleveland and Chicago.