After nearly a decade of review, the Dept. of Interior gave the go-ahead for the nation’s first offshore wind farm the $1 billion Cape Wind project off the coast of Nantucket on April 28. The facility could be operational by as soon as 2012.

But the Interior Dept. says it will require the developer of the controversial project, Cape Wind Associates, LLC to modify its proposal to minimize potential adverse environmental and aesthetic impacts of construction and operation of the facility.

Cape Wind Associates is a joint business venture between Boston-based firms Energy Management Inc. and Wind Management LLP.

The project, which will be built about five miles off the coast of Massachusetts, would occupy a 25-sq-mile section of the Nantucket Sound and generate a maximum electric output of 468 megawatts, with an average anticipated output of 182 megawatts. The project includes a 66.5-miles buried submarine transmission cable system, an electric service platform and two 115-kilovolt lines connecting to the mainland power grid.

The Interior Dept. says the project would create several hundred construction jobs and be one of the largest greenhouse gas reductions initiatives in the nation, cutting carbon dioxide emissions from conventional power plants by 700,000 tons annually, the equivalent to removing 175,000 cars from the road for a year.

Modifications to Cape Wind’s original plan include a reduction in the number of turbines from 170 to 130, and a reconfiguration of the turbine array to diminish any negative visual impact from the shoreline. Additionally, the developer will be required to conduct additional seabed surveys to ensure that any submerged archeological resources are protected prior to bottom-disturbing activities.

A number of similar projects have been proposed for other northeast coastal states. “This is the first of many,” said Interior Secretary Ken Salazar at a briefing in Boston. The Dept. of Interior says the region has the potential to tap 1 million megawatts of offshore Atlantic Wind energy potential.

Some groups, while supportive of DOI’s decision, criticize the lengthy review process for the project. “The thorough review conducted on the Cape Wind project makes it abundantly clear that it passes environmental muster,” says Sean Garren, clean energy advocate for Environment America. “We hope that state and federal officials can take what they have learned from this project and then expedite the deployment of offshore wind while continuing to protect the environment. Our environment and the emerging clean energy economy cannot wait this long for future wind projects to come online.”