Project Parameters

How big would the Cape Wind farm be? Would it include other structures in addition to wind turbine towers?

Cape Wind would include 130 wind turbine generators arranged in a grid pattern on and around Horseshoe Shoal in Nantucket Sound, as well as an electric service platform (ESP), buried electrical cables connecting the turbine towers, and two transmission cables connecting the wind park to the electric transmission grid on land. The developer currently plans to use 3.6 megawatt wind turbines, which would have a maximum overall height of 440 feet (134 meters) and a rotor diameter of 364 feet (111 meters). The turbines’ hubs would be 257.5 feet (78.5 meters) above the sea surface. Rotor blades would have 75 feet (23 meters) of clearance above the sea surface at the lowest point in their rotation. Because wind turbines are undergoing rapid design improvements, the final number of turbines and their exact size could be different if the park is approved and installed.

Generators on each turbine tower would produce electricity, which would be carried by cables from the towers to the electric service platform. From the platform two transmission cables buried under the sea floor would carry the electricity to a landfall point at Yarmouth and then over land to an existing switching station in Barnstable.

The electric service platform would be a fixed platform anchored to the ocean floor in the middle of the wind park and measuring approximately 100 feet by 200 feet (30.5 meters by 61 meters). It would hold an assortment of equipment, including electric voltage transformers, fire protection equipment, battery backup units, and temporary living accommodations in case crews cannot be removed during inclement weather. All equipment would be housed within an enclosed weather-protected service area, and waste from the crew quarters would be pumped to a service vessel for proper disposal.

How much space would Cape Wind occupy in Nantucket Sound?

The total project area of Cape Wind would be 25 square miles (15,980 acres).¹ Of this space, Cape Wind facilities would occupy the following areas:

• 130 wind turbine generators and electrical service platform: 0.67 acres
• Inner-array cables between WTGs and ESP: 4.35 acres
• Transmission line (federal and state waters): 3.92 acres
• Scour protection mats and rock armoring for WTGs: 44.3 acres

In sum, only a small fraction (53.24 acres) of the submerged land within the project area would be physically occupied by structures and components of the wind farm. As discussed below in section H, the Army Corps of Engineers concluded that Cape Wind would not impede navigation in Nantucket Sound because boats would be able to sail along wide lanes between the towers.

¹All figures in this paragraph are from the MMS DEIS, section 2-2, page 2-6