The development of key infrastructure projects can resemble a marathon. It takes long-term commitment and expertise to reach the finish line. As proud sponsors of the 2021 Falmouth Road Race and Cape Cod Marathon Weekend, we put our name on it.
Benefits to Falmouth
2020 Training in Action
From its Buzzards Bay campus, the Massachusetts Maritime Academy prepares cadets with a unique, maritime-focused skillset. Mass Maritime is a key partner in our efforts to expand educational opportunities for students from historically disadvantaged and diverse communities across the region, which will in turn, help equip the local offshore wind workforce.
Mayflower Wind has engaged in a range of outreach and financial contributions to support specialized instruction, scholarships, and career development at Mass Maritime, including:
- Cost-sharing the state’s July 2020 grant funding of $75,000 toward specialized crew transfer vessel and helicopter training and Global Wind Organization advanced rescue training
- Sponsoring the virtual Admiral Scholarship Gala in November 2020 and contributing two seabag scholarships for cadets
- Offering insights into key offshore wind industry issues with 15 cadets on a virtual classroom presentation in April 2021
- Speaking with cadets about seagoing and shoreside jobs at the career fair in September 2021
Offshore to onshore connection
Wind Turbines – Wind turbines convert kinetic energy from the wind into electric power.
Inter-array Cables – Electrical cables connect wind turbines to each other and transport power to the offshore substation at 69 kilovolts (kV).
Offshore Substations – The offshore substations enables the wind farm to operate more efficiently by stepping up voltage from 66 kV to 200-345 kV.
Export Cables – Electric power is transmitted from the offshore substations by electrical cables which will come ashore in Falmouth.
Landfall – The export cables connect onshore via an underground conduit tunneled deep beneath the beach.
Underground Cables – From the beach area, electric cables will be buried beneath town roads and transmit power to the onshore substation.
Onshore Substation – The onshore substation transforms the power to grid voltage, stepping up to 345 kV.
Overhead Lines – An overhead 345 kV transmission line transports the power to an interconnection switching station.
POI – The point of interconnection, or the point where Mayflower Wind’s facilities interconnect with the Transmission Owner’s facilities.
Interconnection Switching Station – The interconnection switching station collects power from the overhead lines and feeds into the transmission system.
Transmission System – An interconnected network of 345 and 115 kV transmission lines deliver electricity to end customers.
A strong commitment to safety
While we will examine the safety of all aspects of the project, one topic of community interest is electro-magnetic fields (EMF). We hired expert consultants to study the potential EMF effects of the cable. They found that there are no safety risks and Mayflower’s electric cables will operate well below established health guidelines. For more information and to view the reports, please see our Health and Safety page.
Your input is valued during the regulatory review process
Mayflower Wind requires local, state, regional, and federal permits and approvals for its nearshore and onshore facilities and activities in Falmouth.
The regulatory review process provides numerous public meetings and comment periods, under the direction of lead federal and state agencies, when you can provide valuable input into the various aspects of the project.
Permitting applications and other regulatory documents are available on the documents page.
Status: MEPA ENF & EFSB Petition Submitted
EFSB Public Comment Hearing
Visit the Environmental Monitor
Search for EEA #16507
Visit the EFSB site
Search for Docket #EFSB 21-02/D.P.U. 21 142/21-143
EFSB Public Comment Hearing postponed until further notice.
For more information:
See the EFSB and DPU Siting Process
View the presentation from the June 8, 2022 Select Board Meeting – Public Forum on Mayflower Wind Proposal
Ways to get involved
We are in the process of reaching out to the Falmouth community and are committed to ensure all Falmouth residents can learn about our project, ask questions, and provide valuable input.
Getting from there to here
The Mayflower Wind project will be located over 30 miles south of Martha’s Vineyard and 20 miles south of Nantucket.
Submarine export cables buried beneath the seafloor will run north through Muskeget Channel and then west towards Vineyard Sound, before making landfall in Falmouth. From there, electric cables buried under roadways will connect power to an onshore substation in Falmouth, and underground transmission lines will deliver power to the Falmouth point of interconnection with the regional electric grid.
Mayflower Wind has identified two potential locations for the subsea export cables to make landfall at Falmouth Heights Beach. The cables will be installed under the beach and coastal ecosystem. Each proposed HDD trajectory will be about one mile in length, at a depth of up to 90 feet below the seabed. Once ashore, the cables will continue underground, in nearly all cases under roadways up to eight feet or deeper, to a much further inland onshore substation at a location that is being determined.
The Falmouth Heights beach locations were selected after initial modeling confirmed the Upper Cape as an optimal point of interconnection into the regional electric grid. Locations along Surf Drive Beach were intensively studied but proved not to be feasible, largely due to technical issues created by existing utility lines.
Studies are being conducted to gather data and assess the suitability of these sites for a complete and reasoned analysis of the preferred and alternative routes.
A final decision on site location will be made after a full routing analysis has been completed. That decision will then be reviewed and require approval by state and local regulatory agencies.
Horizontal Directional Drilling (image courtesy of DEME Offshore US)
Cable Pull-In (image courtesy of DEME Offshore US)
How HDD will work
Following the guidance of the Massachusetts Ocean Management Plan, which protects critical marine habitat and important water-dependent uses and sets standards for ocean-based projects, Mayflower Wind will employ Horizontal Directional Drilling (HDD) to avoid impacts to sensitive environmental resources, including beaches and nearshore eelgrass beds.
The process begins with the creating of a bore hole to support the cable. It will be located well below the surface and will come up well distant of the beach. Each proposed HDD trajectory will be about one mile in length, at a depth of up to 90 feet below the seabed.
After the bore hole is created, the cable will be pulled through and buried under the beach. Using a duct bank and vault system, the cables will then be buried under local roads and connect to a new substation much further inland. Manhole covers all you will be able to see, just like those found along Surf Drive Beach for the existing fiber optic and electric cables to Martha’s Vineyard.
Underground route to substation
The onshore cable route will primarily be installed within existing paved roadways or roadside shoulders. The anticipated method of underground cable installation along the route is open trench installation. Typical excavation depth will be approximately eight feet deep but could be deeper depending on survey results.
The total length of the buried cable from the landfall to the substation is two to eight miles, depending on the location. The preferred location for the substation is at the Lawrence Lynch aggregate and asphalt facility on Stephens Lane. The alternative site is at Cape Cod Aggregates facility located off Thomas B. Landers Road.
The cables will operate at a voltage between 200-345 kilovolts. While most high-voltage transmission lines remain overhead, a growing number of systems include underground 345 kilovolt cables through densely populated areas, including a recent Eversource project from Woburn to Wakefield.
The maximum footprint of the onshore substation site will be up to 26 acres. Major components at the onshore substation include air-insulated circuit breakers, switchgear, and 345 kilovolt transformers. As the substation equipment and layout is refined, Mayflower Wind will refine noise mitigation strategies such as low-noise transformers, enclosing of certain substation components, and sound barriers.
Connecting at Falmouth Tap
Eversource will be responsible for constructing and operating a new two- mile overhead line to the point of interconnection at Falmouth Tap, as well as the Falmouth Tap grid connection.
Falmouth Tap currently consists of an existing substation owned by Eversource, which will be upgraded in the future to accommodate Mayflower Wind.
The Falmouth Tap grid connection provides access to the existing 345 kilovolt overhead transmission lines that transmit across the Cape Cod Canal to Carver and Plymouth. An interconnected network of transmission and distribution lines ultimately deliver electricity to end customers of the New England regional system.
Contact our community liaison
This page will be updated frequently so we encourage you to visit often and/or sign up for our email updates.
Frequently asked questions
How did Mayflower Wind decide the route for the export cables?
Route alternatives are currently being evaluated according to environmental, technical, and commercial factors, and will be presented in the project’s filings with federal, state, and local agencies. 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.
Where will the project make landfall?
Mayflower Wind is examining two landfall locations along Falmouth Heights Beach in Falmouth. 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 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.
What is the maximum export cable voltage Mayflower Wind could use, and how does voltage relate to EMF?
Mayflower Wind’s preferred transmission technology for interconnection to Falmouth is high voltage alternating current (HVAC) export cables. The nominal voltage for the selected cables could be up to 345 kilovolts (kV), which corresponds to an equipment voltage class of 362 kV. The operating voltage could therefore fluctuate up to 362 kV.
The term EMF describes the combined characteristics of electric fields and magnetic fields. Voltage directly determines the electric field, however, the HVAC export cables that Mayflower Wind would use are constructed in a way that produces negligible electric field outside the cable, regardless of voltage class. Therefore, Mayflower Wind’s modeling analysis of HVAC EMF is focused on magnetic fields. Magnetic field size is directly determined by current. The magnitude of the current in the cables will be limited by the thermal constraints of the cables, a property which is generally independent of cable voltage class. The voltage class of Mayflower Wind’s HVAC cables does not correlate to magnetic field size.
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.
What studies have been conducted to determine whether the project can safely and reliably interconnect into the regional grid?
Mayflower Wind is continuing with efforts to connect its low-cost clean energy into the New England electric grid via the Falmouth interconnection point. The timing of these efforts is subject to the schedule of transmission upgrades overseen by the regional grid operator, Independent System Operator- New England (ISO-NE).
Through this study process, ISO-NE determines how the project can safely and reliably interconnect into the New England transmission system. This includes conducting a Feasibility Study and System Impact Study, which are performed to ensure that system reliability criteria and standards for no adverse impact are met.
How will the project benefit Falmouth?
Falmouth will benefit from hosting a major clean energy infrastructure project through additional revenue, local construction jobs, and business activity. A Host Community Agreement is an essential tool for providing revenue to the Town with payments during operations. Payments may support local-driven initiatives, such as coastal resiliency, energy efficiency, and other priorities, as determined by the Town. Construction of the landfall, underground cabling, and onshore substation will create demand for a variety of qualified contractors and local retail businesses.
Mayflower Wind looks forward to being a long-term member of the Falmouth community and an active participant in activities such as local school STEM, renewable energy education programs, and workforce training.
How does EMF modeling compare to measured values in the field?
Mayflower Wind’s modeling analysis of HVAC EMF uses conservative operational inputs. The modeled currents represent maximum loadings for the cables by assuming the wind farm is operating at 100% output and delivering 1,200 MW. As a renewable resource dependent on weather patterns, the actual output of the offshore wind farm will vary and typically be less than 100%. Further, the modeling analysis includes conservatively shallow cable burial scenarios and looks at a variety of physical cable arrangements. For all these scenarios, the maximum predicted magnetic field for the Mayflower Wind project to Falmouth is less than the health-based guideline of 2,000 milligauss (mG) for allowable public exposure to 60 hertz (Hz) HVAC magnetic fields, established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in 2010. The modeling is purposefully conducted with conservative assumptions so that predictions in the report exceed what would be measured once the wind farm is operational.
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.
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.
Does the landfall cable installation, when completed, expose human beings and living things to any kind of dangerous emissions operational?
No. The landfall cable installation is using the same process as currently operates at Surf Drive Beach, near Shore Street, where four Eversource offshore cables are buried in a duct bank and manhole system.
Why not use horizontal drilling for the entire on-land installation?
The existing world record length for horizontal directional drilling (HDD) is about 2.5 miles. The total current anticipated HDD length for the Mayflower Wind project is about one mile. The entire length of the onshore cable route from either landfall to potential substation is between two to eight miles.
Why does the undersea cable go to Falmouth instead of Bourne, Mashpee, Barnstable, or Plymouth?
Cape Cod and Southeastern Massachusetts are at the outer reaches of the regional transmission system with limited supply options. Numerous conditions limit how much energy can be injected at a specific location on the electric grid without requiring major upgrades to the system. Mayflower Wind evaluated more than 10 different grid interconnection locations, and identified Falmouth and Brayton Point as the optimal points. Each grid connection point allows access to the existing interconnected network of transmission and distribution lines that ultimately deliver electricity to end customers of the regional system.
Did you consider an above-ground cable system in Falmouth instead of an underground system?
An above-ground cable system for the onshore route to the substation was ruled out due to a variety of technical, permitting, and community impacts.
From either substation site, Mayflower Wind will interconnect to the grid using transmission lines in the existing utility right of way. This approach would reduce the length of the underground route in public roadways.
Is there a transition vault on Falmouth Heights Beach?
No. The transition vault would be located underneath the median park at Worcester Avenue.
Who will approve or disapprove the proposed Falmouth route?
The state level reviews by the Massachusetts Energy Facility Siting Board (EFSB) and the Environmental Policy Act office (MEPA) are the two key regulatory processes that drive most of the other state and local permitting timelines.
The EFSB is an independent state board that reviews proposed large energy facilities, including electric transmission lines, to determine if they serve the public interest.
Mayflower Wind will work cooperatively with the Town of Falmouth on construction scheduling, including seeking licenses where necessary to facilitate construction access.
How long do you expect the onshore construction process to take?
Lane or road closures in Falmouth would use a rolling setup, so only a section of the roadway is actually being worked at a given time. The entire onshore construction process, including the underground cabling and substation, could last up to 1.5-2 years, depending on a number of factors.
What month of year do you anticipate the onshore cable installation to begin and end?
Onshore cable installation will occur outside of the busy summer season to the maximum extent practicable.