Cape Wind Associates completed its federal permitting process yesterday, a decade after it announced plans to build the nation’s first offshore wind farm in Nantucket Sound. The US Environmental Protection Agency issued an air quality permit for construction and operation of the proposed 130-turbine wind farm. The permit was issued 24 hours after the US Army Corps of Engineers issued another permit for work in navigable waters. With the permitting complete, Cape Wind is working on financing the project, estimated to cost more than $2 billion. Opponents have pledged to continue fighting the project on numerous grounds.