The initial plan calls for about 60 large wind turbines about 11 miles east of Rehoboth Beach. Bluewater Wind LLC could begin delivering energy to Delaware customers by 2012 under the current schedule.
It could become one of the first offshore wind farm in the United States. Another project proposed for Massachusetts' Nantucket Sound is slated for completion in 2011, but it still faces regulatory and legal hurdles.
The Delaware project is subject to regulatory oversight by the federal government and has won support from area environmentalists.
The bill approves a 25-year power-purchase agreement to allow Delmarva Power to buy up to 200 megawatts of electricity from the project operated by Bluewater Wind LLC.
"We need to get away from the fossil fuels. We need to get away from dependence on foreign oil," Gov. Ruth Ann Minner said in signing the measure hours after it unanimously passed the House and Senate.
Delmarva Power and Bluewater spent months wrangling over a power purchase agreement that would allow the project go forward.
The deal allows Bluewater to sell leftover energy credits on the open market, making the project economically feasible for the wind farm developer while saving Delmarva Power customers an estimated $100 million.
It also requires that the costs associated with wind-based electricity be spread through a surcharge across Delmarva Power's entire Delaware customer base, not just among its standard residential customers.
"Everybody gave a little bit, and that's what tends to make things happen," said Senate Majority Leader Anthony DeLuca, D-Newark, who guided negotiations.
The Public Service Commission last year approved Bluewater's proposal for a wind farm, supplemented by a natural gas facility in southern Delaware to provide backup power when the wind doesn't blow.
Initially, Delmarva lobbied heavily to defeat the proposal, which it claimed would burden its customers with costly premiums for offshore wind when they could obtain more affordable land-based wind power from other states.
Under the agreement announced Monday, Delmarva Power will buy about half of the amount of wind power suggested under an earlier proposal, and at a lower price per megawatt hour. The price drop is due to a reduction in the costs that Delaware customers will pay for renewable energy credits.
"This is a far, far better deal than we started with," said Sen. Harris McDowell III, chairman of the Senate energy committee.