Vineyard offshore wind project reaches accord on export cable route

Vineyard Wind has reached a settlement in Massachusetts that will allow it to utilise an undersea transmission corridor to connect the first major US offshore wind farm south of Martha’s Vineyard with the mainland electric grid.

The Conservation Commission in Edgartown on the island agreed to drop its earlier opposition to Vineyard laying two export cables beneath the seabed from the future 84-turbine array to one of two possible landfall sites on Cape Cod.

The project developer had appealed the Commission’s decision to deny a permit with the state, the other signatory to the settlement.

Under state law, the Commission has jurisdiction for certain bottomlands near Martha Vineyard’s eastern shore in Muskeget Channel, a mid-point in the cable corridor before it enters Nantucket Sound – the nearest body of water to shore.

Plans call for burying two cables in the corridor at 1.5 metre depth. Each will consist of three smaller diameter core 220kV alternating current cables. The route from the array’s electrical service platforms to landfall will be 22-24km (14-15 miles).

Once ashore, the cables would then run underground to a new electrical substation that will be built next to an existing one in Hyannis.

Preserving the export cable corridor is important for the project because of its first-mover advantage. It represents an almost straight shot to the mainland whereas future projects in four other nearby lease areas may not have such favourable routings to connect with the onshore grid – and that could raise the cost of construction and permitting.

The settlement is also milestone in Vineyard’s ongoing effort to advance the $2.8bn, 800MW project toward construction, which the Department of Interior (DOI) delayed in August to conduct further environmental review.

The Bureau of Ocean Energy Management (BOEM), part of DOI, has indicated that it intends to complete the study late this year or in early 2020 and then open it to public comment.

BOEM, which oversees wind energy development in federal waters on the outer continental shelf, had set a 15 March 2020 target deadline for completing its project regulatory reviews. That was before DOI ordered the supplemental environmental study.

Industry participants believe BOEM will eventually approve the project sometime next year. The agency will likely require changes to the project that address commercial fishing industry concerns and perhaps others involving “cumulative impacts” from Vineyard and later projects could have on the regional ecosystem.

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