Why It’s So Hard to Build Offshore Wind Power in the U.S.

For years, the mighty wind blowing off the Massachusetts coast has beckoned developers with visions of clean, emission-free electricity. The latest to be seduced, Vineyard Wind LLC, aims to install 84 Statute of Liberty-size turbines about 15 miles off the state’s shoreline, which would together generate enough electricity to power 400,000 homes as soon as 2022.

The project hit a snag in August, when the U.S. Department of the Interior ordered additional analysis of how the wind farm—and potentially 14 others that have been granted leases across almost 1.7 million acres of Atlantic waters—would affect the $1.4 billion fishing...