Technology advances and competition have prompted the University of Maine to change the design of its VolturnUS, a wind turbine mounted on a floating platform. The new platform will be slightly larger to accommodate a 9.5-megawatt turbine and tower, compared with the original 6-megawatt turbine. The hub of the rotor blade will now stand 360 feet above water, compared with 328 in the previous design. Also, the rotor diameter will expand from 495 feet to 570 feet. Courtesy University of Maine

A pending $5 million federal energy grant to help the University of Maine design larger platforms for a coming generation of floating offshore wind farms reflects a new reality in the wind power industry: turbine sizes that seemed unimaginable only 10 years ago.

UMaine and its Maine Aqua Ventus partners have been trying since 2014 to get a pair of their patented, semi-submersible platforms in the waters off Monhegan Island, with two, 6-megawatt turbines atop. A commercial-scale project like that would have a blade height 576 feet above the waterline and could generate enough electricity to power 6,000 homes.

But this year, General Electric introduced a 12-megawatt offshore turbine with an 853-foot blade height, more than two football fields in length.

“It’s the passage of time and this industry is moving,” said Jeff Thaler, the  university’s associate legal counsel and the legal counsel for Maine Aqua Ventus. “Maine had stalled for a while. To be relevant, we have to keep up.”

Maine Aqua Ventus now wants to beef up its platform design to accommodate a single 9.5-megawatt turbine for the Monhegan site, rather than two smaller units. The target date is 2022, seven years later than originally estimated.

UMaine’s bid to be a player in the emerging offshore wind industry has suffered repeated setbacks. Most notably, it was hobbled during the administration of former Gov. Paul LePage, a wind power critic, and a skeptical, LePage-appointed chairman at Public Utilities Commission. Despite that, Maine Aqua Ventus remains poised to become the first commercial-scale floating wind farm in the United States, according to a federal energy expert who has followed the project for years.


“It’s the furthest along,” said Walter Musial, principal engineer at the National Renewable Energy Laboratory in Golden, Colorado. “I don’t see any technical barriers and a lot of the political barriers have been mitigated.”

Getting the project floating in 2022 would help prove the viability of the UMaine design, just as the global floating wind industry is poised for growth. That could create a market to build the reinforced concrete hulls in Maine, Thaler said, as well as license the technology for construction elsewhere.


Offshore wind farms have helped power Europe for decades. Now a new wave of multibillion dollar projects is taking shape along the East Coast of the United States. But these ventures involve turbines set on towers driven into nearshore seabeds. The current challenge is to design turbine-support platforms that can be anchored in deep water 10-20 miles offshore, out of sight of land and in areas where winds are stronger and steadier.

In 2017, Norwegian energy giant Equinor built the world’s largest floating wind project, the 30-megawatt Hywind pilot project off Scotland. That wind farm – once planned for Maine when the company was named Statoil – has five, 6-megawatt turbines. Now Equinor is building an 88-megawatt floating farm off Norway, Hywind Tampen, using 8-megawatt turbines. They will stand on a floating steel “spar buoys,” cylinders filled with ballast consisting of water and thousands of tons of iron ore.

Next year, a 50-megawatt floating project off Scotland, Kincardine Offshore Wind, is planned to launch with semi-submersible platforms designed by a Maine Aqua Ventus competitor, Principle Power. That project will use 9.5-megawatt turbines built by Danish concern Vestas, the same ones being considered for Monhegan.


Musial said most of the world’s floating offshore projects under construction or in the planning stages involve semi-submersible platforms like the ones Maine Aqua Ventus and Principle Power have designed, although Equinor’s spar also has proven to be commercially feasible.

This industry scale up in turbine size is based on physics. Wind energy increases with the cube of the wind speed, meaning that doubling the wind speed creates eight times the energy. That’s why developers are looking at places, such as the Gulf of Maine, that are both near population centers and feature high, sustained winds that can be captured by massive turbines.

UMaine has been refining its technology since 2013, and received its first in a series of federal energy grants, $3 million, in 2014. Two years later, the federal Department of Energy selected Maine Aqua Ventus as a primary project in a nationwide competition and awarded it $40 million. Last week, the DOE announced a series of awards, including the $5 million for UMaine to refocus its research and development on the larger platform.

In this 2013 photo, the country’s first floating wind turbine, the University of Maine’s 9,000-pound prototype, generates power off the coast of Castine. The project has been delayed repeatedly, but is now being updated to compete with other offshore wind farm technology. Associated Press/Robert F. Bukaty

During this drawn out period, Maine Aqua Ventus successfully tested a one-eighth scale prototype of the platform off Castine. It won – and then lost – a critical power-purchase contract at the PUC that would have provided a revenue stream to attract investors. Earlier this year, a resolve by the new Democrat-controlled Legislature that was backed by Gov. Janet Mills told the PUC to approve the long-term contract. That action is still pending.

Thaler expects the new platform design to be slightly larger to accommodate the 9.5-megawatt turbine and tower. The current design features three columns that extend 301-feet in diameter and float 66 feet below the surface.

Based on data from the maker, MHI Vestas, the rotor diameter will be 570 feet, compared to 495 for the 6-megawatt option. The hub or center of the rotor blade will stand 360 feet above the waterline, compared to 328 feet.


Moving to a single larger platform will result in a smaller footprint on the site, which is in state waters south of the island. There will be fewer anchor chains, Thaler said, and less impact on lobster fishing and bird migration. The overall development cost may be less, he said, but the expense of running cable to the mainland and increased prices for concrete and steel could cancel out any savings.

Ratepayer impact had been at the source of opposition from LePage and the PUC. The proposed long-term contract would cost Central Maine Power customers an extra 73 cents per month on their bills. Supporters said it’s a small price to help kick start a new industry in Maine.

The project’s resurgence will be of great interest in the coming months on Monhegan. The community negotiated a benefits agreement with Maine Aqua Ventus, but some residents remain opposed.

Travis Dow, a long-standing critic, said he was disheartened to hear the news. In his view, this is the third time the project size has changed shape, from a short-term test proposal, to two, commercial-scale turbines and now to one larger one. He wondered if new environmental impact studies should be done and why the project hasn’t settled on a cable landing site yet.

“So many questions,” he said. “So few answers. And unfortunately, it is impossible to trust anything they say anymore.”

Thaler said UMaine has reached out to island residents over the last week with new information.

Maine Aqua Ventus has said that any development of a larger wind farm following the demonstration would be in federal waters farther offshore, not near Monhegan.

Musial, the government wind engineer, said he sees the potential for floating wind someday in deep water off the Maine coast. That would follow the current wave of projects in shallow water off southern New England.

“There’s a big load (electricity demand) and the Gulf of Maine could serve southern New Hampshire and Massachusetts,” he said. “To get a lot of new development, they’ll need new areas that are farther out.”

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