The Mayflower wind farm is a 1.6GW offshore wind power project proposed to be developed approximately 32km south of Martha’s Vineyard, Massachusetts, in the New England region of US.

Mayflower Wind Energy, a 50:50 joint venture between Shell New Energies and EDP Renewables, is the developer of the project.

An 804MW wind farm is planned to be developed in stage one which is expected to commence operation in 2025.

The Mayflower offshore wind energy project is expected to generate enough electricity at a cost as low as 5.8 US cents per kilowatt-hours (KWh) for approximately 680,000 households a year.

The project is expected to create approximately 10,000 jobs and offset approximately 1.7 million tonnes (Mt) of CO2 emissions a year once in operation.

Location and site details

The Mayflower offshore wind power project is located on a 127,388acre federal lease area on the Outer Continental Shelf (OCS), approximately 40km south of Nantucket, Massachusetts, US.

Mayflower wind project background

Mayflower Wind Energy won the rights to develop up to 1.6GW of commercial wind energy on a federal lease area on block 0521 in the Outer Continental Shelf (OCS) off the coast of Massachusetts, in an auction organised by the US Bureau of Ocean Energy Management (BOEM) in December 2018.

Mayflower Wind Energy submitted four bids including proposals for three 804MW wind farms and a 408MW wind farm to the Commonwealth of Massachusetts Section 83C offshore wind development procurement process in August 2019, of which the lowest-cost 804MW wind farm proposal was selected in October 2019.

A high-resolution geophysical survey campaign in the Mayflower Wind project area was initiated in July 2019 and completed in October 2019.

Mayflower 1 wind farm  design

The turbines of the 804MW Mayflower 1 wind farm will be installed on monopole foundations in rows in water depths ranging from 35m to 65m. The distance between the turbine rows will be approximately one mile.

The electricity generated by the turbines will be gathered and transmitted to an offshore substation through approximately 300km of 66kV inter-array cables.

The electricity from the offshore substation will be further transmitted to an onshore substation via export cables.

Power off-take

The electricity output of the wind farm will be off-taken by Massachusetts electric utilities under long-term power-purchase agreements.

The electric distribution companies (EDCs) that have applied for long-term contracts with Mayflower Wind Energy include the NSTAR Electric Company, Nantucket Electric Company, Massachusetts Electric Company, and Fitchburg Gas and Electric Light Company.

Contractors involved

A joint venture of Semco Maritime and Bladt Industries was contracted for the fabrication and delivery of a 1.2GW offshore substation in January 2020.

Bladt Industries will undertake the steel structure and jacket foundation works while Semco Maritime will be responsible for the design, procurement, and installation of electrical equipment, auxiliary systems, and inter-array cables.

Siemens was subcontracted by Semco Maritime to provide the main electrical equipment for the electrical service platform (ESP) of the Mayflower wind power project in June 2020.

As part of the contract, Siemens will supply three 275 kV/265 MVAr shunt reactors, a 72kV HV gas-insulated switchgear (GIS), three 275 kV MV GIS systems, integrated conditioning monitoring system, as well as SCADA and protection systems for the Mayflower offshore substation.

Power and telecom cable manufacturer Hellenic Cables was subcontracted by Semco Maritime to design and supply 300km of 66kV, XLPE insulated submarine inter-array cables for the wind farm in January 2020.

TerraSond, a subsidiary of the global subsea services group Acteon, was engaged to conduct a high-resolution geophysical survey for the Mayflower wind farm project in 2019.