Project FAQs

Where will the project be located?

The wind turbines, inter-array cables, and offshore electric substation for the Mayflower Wind project will be located in the Atlantic Coast Outer Continental Shelf lease area OCS-A 0521, which is over 30 miles south of Martha’s Vineyard and 20 miles south of Nantucket.

In order to maximize the potential of the lease area capacity, Mayflower Wind is pursuing dual export cable routes to deliver the power to electricity customers via interconnection points at Falmouth and Somerset, Massachusetts.

  • Submarine export cables will extend north through Muskeget Channel and then west towards Vineyard Sound, before making landfall in Falmouth, which is over 50 miles away. Underground electric cables will connect power to an onshore substation in Falmouth. Underground transmission lines will extend from the Falmouth substation to the Falmouth point of interconnection to the regional power grid.
  • Submarine cable routing from the lease area to Brayton Point, which is over 70 miles away from the offshore lease area, is still being determined, based upon ongoing surveys, studies, and the permitting process. The routing would extend northwest through Rhode Island state waters, the Sakonnet River, and Mount Hope Bay, with a buried underground crossing in Portsmouth, before connecting power to Brayton Point Interconnection.

No final decisions on site locations for project facilities will be made until a full routing analysis has been completed. Baseline surveys are currently underway to gather data on-site and assess the suitability of alternative sites for a complete and reasoned analysis of the alternatives.

How many acres are in the federal offshore lease area?

123,388 acres. 

How much power will Mayflower Wind generate?

We are developing a federal offshore lease area that has the potential to generate over 2,000 megawatts (MW) of power, depending on technology. That is enough energy to power close to 800,000 homes.

What is the overall project timeline?

We expect to deliver clean energy from the project by the mid-2020s. 

Who will benefit from the project?

Individuals and communities across Massachusetts will benefit from the Mayflower Wind project.

Both residential and business ratepayers will benefit from low-cost energy generated by the project, saving over $2 billion on electric bills over the project’s lifetime, according to the Massachusetts Department of Energy Resources. Wind power from the project will enhance electric system reliability, especially in peak winter months.

The project will support new jobs and supply chain growth across all phases—development, construction, and operations. In particular, the project has committed to ensure at least 75% of all operations and maintenance jobs are local.

Governments at all levels benefit from the increased revenue and economic activity. The US government has received $135 million for the federal offshore lease payment. The project is estimated to provide nearly $2.5 billion in total economic benefit to the Commonwealth.

Over the 20-year contract period, citizens in Massachusetts will benefit from cleaner air, as the project will eliminate over thirteen million metric tons of greenhouse gas emissions system-wide once in operation.


What permits and licenses does Mayflower Wind need before it can start construction?

The Mayflower Wind project will require local, state, regional, and federal permits and approvals for relevant onshore, nearshore, and offshore work. Mayflower Wind has the experience, knowledge, and capacity to obtain the permits and approvals necessary to develop and operate offshore energy projects.

Mayflower Wind received approval of its Site Assessment Plan from the federal Bureau of Ocean Energy Management (BOEM) in May 2020 and is currently undertaking onshore and offshore baseline surveys required to advance engineering and evaluate potential environmental, historical, cultural and social impacts. These efforts have been, and will continue to be, pursued with input from communities and stakeholders to ensure a safe, reliable, and responsible project.

How can the public be involved in reviewing the project?

Public participation in the offshore wind development process is critical. Early input from stakeholders helps inform project design and planning. Mayflower Wind is committed to developing the project through an open, transparent, and collaborative process.

The permitting and regulatory review process includes formal public meetings and public comment periods to allow all interested parties to share information and submit feedback. We encourage people to contact us if they have questions or would like to learn more about the project.

Who is responsible for removing the project facilities if it is no longer operational?

Mayflower Wind will comply with all federal US Bureau of Ocean Energy Management (BOEM) requirements for decommissioning, including removal of necessary facilities, cables, projects, and obstructions on the seafloor. Federal offshore Lease obligations require Mayflower Wind to set up a decommissioning fund. As part of the project approval process, Mayflower Wind will develop a preliminary decommissioning plan. This plan will continue to be reviewed and improved over the operating life of the project to incorporate new discoveries and advancements in the fields of marine science and engineering, as well as lessons learned from the offshore wind industry and other offshore operations.

How much power will interconnect to Falmouth? 

Mayflower Wind intends to maximize output from the offshore lease area, which has the potential to generate over 2,000 megawatts (MW) of low-cost clean energy. To enable energy from the lease area to flow into the regional transmission grid operated by ISO New England, Mayflower Wind must go through the ISO New England interconnection process. ISO New England has a planning requirement that, in effect, limits the capacity of a single project at a single point of interconnection to no more than 1,200 MW. As a result, developing the full potential of the lease area will require two sets of transmission interconnection facilities. Mayflower Wind plans to utilize one point of interconnection in Falmouth, Massachusetts, and another at Brayton Point in Somerset, Massachusetts. Our simultaneous pursuit of 1,200 MW of capacity at Falmouth and 1,200 MW of capacity at Brayton Point gives us flexibility for the future.

Why is Mayflower Wind seeking exemption from Falmouth’s bylaw 240-166 Wind Energy Systems?

Energy infrastructure projects are sited in the public interest through extensive routing and public participation processes. In order to assure that projects can be completed, the entities building them have the right to seek exemptions when necessary to allow for the timely construction of the project. Exemptions from local zoning bylaws must meet well-established criteria set by the Department of Public Utilities. Mayflower Wind is seeking an exemption from the bylaw 240-166 in order to build the project in Falmouth.

Are there other 345 kV cable projects that are currently in service in densely populated areas?

Yes, the existing Eversource transmission system in Falmouth, to which Mayflower Wind is seeking to interconnect, includes 345 kilovolt (kV) overhead lines. A 345 kV line connects West Barnstable to Bourne.

Recent examples of 345 kilovolt underground cable projects include the Woburn to Wakefield, Massachusetts, project, 8 miles long; and the Middletown to Norwalk, Connecticut, project 22 miles long; installed in multiple densely populated areas.

A 65 mile long 345 kilovolt submarine cable, the Hudson Project, delivers 600 megawatts of power between New Jersey and Long Island. An additional separate 65 mile long 500 kilovolt submarine cable, the Neptune Project, delivers another 600 megawatts of power between those same neighborhoods.

Existing electrical infrastructure in Europe and Asia includes underground transmission cable rated up to 500 kV.

What are the tradeoffs between DC vs. AC?

Generally, high voltage direct current (HVDC) technology is considered more efficient for transferring large amounts of power over long distances, as it incurs less power loss when compared with equivalent alternating current (HVAC) systems.  However, HVDC systems require converter equipment that is traditionally more costly and has a more limited supply chain.

The threshold above which HVDC can be a better choice is at distances of about 60 to 75 miles.

As a result, HVAC is the preferred technology for the delivery route to Falmouth, while HVDC technology will be used for the delivery route to Brayton Point.

Do you plan on leasing or purchasing the property at Brayton Point?

Mayflower Wind would lease property at Brayton Point for onshore transmission and grid connection.

How will the project benefit Somerset?

Construction of the underground cables and converter station at Brayton Point will create job opportunities for a variety of qualified local contractors, in areas such as surveying, grading, aggregate and concrete, and other civil and electrical engineering. Local retail and hospitality businesses will see increased activity for goods and services. We encourage interested contractors and suppliers to register with us.

How will the project benefit Portsmouth?

Construction of the underground cables in Portsmouth will create job opportunities for a variety of qualified local contractors, in areas such as surveying, grading, aggregate and concrete, and other civil and electrical engineering. Local retail and hospitality businesses will see increased activity for goods and services. We encourage interested contractors and suppliers to register with us.

How many turbines are you planning to install?

The lease area has 149 positions to install wind turbines and offshore substation platforms.

What is the projected cost of Mayflower wind from conception to ready to operate?

The estimated total cost is about $5 billion.

Does Falmouth receive power or is energy just traveling through to the grid?

Electricity customers of distribution companies from across the Commonwealth will benefit from Mayflower Wind’s clean energy resource as the power will contribute to their power consumption and the decarbonatization of the electrical grid.

Eversource is the incumbent utility for Falmouth and Cape Cod, as well as for New Bedford and much of the SouthCoast – though Somerset and Fall River are located in National Grid’s service territory.

In addition, Mayflower Wind supports efforts by Falmouth State Representative Dylan Fernandes to allow municipal aggregators, such as the Cape Light Compact, the ability to enter direct financeable long-term contracts with offshore wind developers. The Compact is a green aggregator that matches its customers usage in the 21 towns on Cape and Martha’s Vineyard with various supply options.

Are there any land purchases or eminent domain takings?

There are no takings. The project will primarily be installed underneath public property (existing paved roadways or roadside shoulders) and above-ground at a substation, which will be located on private property. Negotiations with private property owners are conducted in a manner that is respectful of their property rights.