While the US vision for offshore wind culminates in the vast reaches of the Gulf of Maine, a cross-border coalition of energy and transmission developers and suppliers is urging the nation to look even farther afield, to the windy sweeps of coastal Nova Scotia, Canada.

The New England-Maritimes Offshore Energy Corridor (NEMOEC) coalition released its white paper today, A New England - Maritimes Offshore Energy Corridor Builds Regional Resilience for a Clean Energy Future, in which it urges development of an offshore ‘backbone grid’ of 525kV high voltage direct current (HVDC) off the Atlantic coasts of both countries.

The 2GW line would traverse 621 miles (1,000km) from Nova Scotia, the Canadian province some 450 miles (724km) northeast of Boston, and southern New England that could offer benefits totalling some $780m annually for ratepayers through market efficiencies.

The concept is for a “shared corridor where projects in Nova Scotia and the Gulf of Maine could interconnect, and you can be moving electricity bi directionally,” said Abby Watson, president of Groundwire Strategies, the consultancy that is driving the effort.

Multiple projects could link to the at-sea cable, which would interconnect to the onshore grid at fewer coastal points compared to radial lines bringing each project individually to shore. The result would be lower environmental impacts and less risk of stakeholder opposition.

“This is not an export play,” Watson added. “This is a balancing resource for the region.”

The six states in New England – Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, and Maine – are among US leaders in climate and emissions targets but their small geographies and dense populations challenge onshore renewable development.

The region has already set targets for some 14GW of offshore wind, while studies show that Massachusetts alone will need some 20GW of offshore wind capacity by 2050 to meet its net-zero goals, with the remainder needing another 10GW.

The Rhode Island and Massachusetts wind energy areas (WEAs) are the US’ largest, but they are largely subscribed with some 6GW of project offtake contracted to multiple states.

Nova Scotia’s government meanwhile released a plan at WindEurope last month calling for leases holding some 5GW of capacity sold no later than 2026, with turbines expected to be installed by the end of the decade.

“Wind in the Gulf of Maine is not generating at the same time as it is off the coast of Nova Scotia, and vice versa,” Watson told Recharge. A subsea connecting line would enable power to continue to flow to each region without necessarily resorting to fossil fuel peaker plants.

Theodore Paradise, chief policy and legal officer for floating wind developer Hexicon, told Recharge that offshore wind generators on either side of the border “are going to want markets to send excess power to, they're going to want markets to arbitrage with.”

“Market optimisation is one of the big benefits,” he added. Hexicon is a member of NEMOEC and has proposed a project for the Gulf of Maine WEA.

Along with Hexicon, coalition members include Atlantic Canada Offshore Development, a joint venture (JV) of Copenhagen Infrastructure Partners and Shell; Bear Head Energy; DP Energy; Grid United; Northland Power; and TotalEnergies SBE, a JV of Total and Simply Blue.

A cross border, at-sea HVDC transmission line would also take pressure off onshore grids, which are historically difficult to expand in the face of widespread opposition.

Collectively the New England states issued a request for proposals last year for transmission solutions to meet climate targets, which included an offshore grid component.

Canadian power

With little more than a million residents, Nova Scotia doesn’t have much power demand. It does have excellent wind resources, however, averaging 13 metres per second (m/s) that outdo even the Gulf of Maine.

Extensive areas of shallow water make fixed bottom foundations feasible, another cost-advantage over Gulf of Maine, which will almost certainly require floating wind on account of water depths in the WEA ranging from 200 to 400 metres.

A Canadian offshore wind sector will also not need to contend with the Jones Act, a maritime law that prevents foreign-flagged vessels from calling in at consecutive US ports or points on the outer continental shelf (OCS), including wind turbines.

“It's my prediction that Nova Scotia will be able to produce the world's cheapest offshore wind,” said Watson.

The concept would need to overcome multiple hurdles, including a sluggish US permitting process and Canada's lack of regulatory regime for offshore wind. Bottlenecks are also appearing in the manufacturing of HVDC transmission cables that could also challenge the idea.

The white paper is aimed at guiding policy makers towards efficient solutions that could enable renewable energy deployment at greater savings.

“Decisions about how transmission RFPs [requests for proposals] look in the next year or two from New England might be materially different, because they've seen data that shows this is a good way for us to meet our, our targets,” said Paradise.

Chart detailing bathymetry of Gulf of Maine and coastal Nova Scotia Photo: Massachusetts Bureau of Geographic Information