PROVIDENCE, R.I. — The federal government will for the first time sell competitive leases for wind energy on the outer continental shelf as it holds an auction for leases for wind farms off the coast of Rhode Island and Massachusetts.

The auction will be held Wednesday, although the Bureau of Ocean Energy Management said it could stretch into Thursday.

The area will be auctioned as two leases. It is 9 nautical miles off the coast of Rhode Island, sitting between and to the south of Block Island and Martha’s Vineyard.

The Department of Energy estimates that the area could support enough electricity to power more than 1 million homes.

There are currently no offshore wind farms in the United States, though several are being developed in state and federal waters.