An experimental offshore wind power project conceived a dozen years ago took a major step forward Wednesday.

The University of Maine will collaborate with New England Aqua Ventus LLC, which includes two global energy companies that are investing $100 million in the project. That investment comes on top of $47 million in grants already awarded by the U.S. Department of Energy.

Diamond Offshore Wind, a subsidiary of Mitsubishi Corp., and RWE Renewables, the world’s second-largest offshore wind company, have joined the public-private partnership, the university announced Wednesday. The goal is to show the feasibility of a full-scale, floating wind turbine in deep water, where winds are more consistent and turbine blades are out of sight from the mainland.

Chris Wisseman, CEO of Diamond Offshore Wind, said his company and RWE are currently responsible for about a quarter of the world’s offshore wind energy supply, most of it produced in shallow coastal waters.

“We’re both keenly interested in floating offshore wind,” Wisseman said. “Offshore wind has really taken off in the last decade and floating fits in places like Maine, California and Japan where the oceans are really deep.”

Using a floating concrete hull featuring a can-and-box design commonly used to build bridges, the project will support a 10- to 12-megawatt wind turbine 2 miles south of Monhegan Island and 14 miles from the Maine coast. Three mooring lines will anchor the hull in 300 feet of water.


“The beauty of this technology is that you can make it locally,” said Dr. Habib Dagher, executive director of the university’s Advanced Structures and Composites Center, where the VolturnUS hull technology was invented. “That keeps jobs local, too.”

Other advantages of concrete hulls over steel are lower cost, more availability and resistance to corrosion, Dagher said. The concrete hulls are designed to last 100 years, compared with 25 for those made of steel. That means concrete hulls potentially could be reused after having a new turbine mounted.

Another, similarly-scaled project in Maine was proposed by an offshore wind developer formerly known as Statoil, now Equinor. That $120 million proposal was scrapped in 2013 after facing opposition from former Gov. Paul LePage.

A lobster boat passes the country’s first floating wind turbine, an experimental, small-scale version off the coast of Castine, in September 2013. Associated Press/Robert F. Bukaty

However, the University of Maine Advanced Structures and Composites Center and the Aqua Ventus consortium pressed ahead with their designs and built a prototype at 1:8 scale. They deployed it off Castine for a year and a half and observed it through 40 storms, using 50 sensors. One winter storm, on Dec. 15, 2013, produced waves that would be equivalent to 60 feet for a full-scale model, and the platform barely moved.

“That was our ‘aha’ moment,” Dagher said. “We learned a lot from that.”

In late 2019, the Maine Public Utilities Commission approved a 20-year power-purchase agreement that requires Central Maine Power Co. to buy electricity produced by the floating wind project.


The terms, initially forged in 2013, require CMP residential customers to pay 23 cents per kilowatt-hour in the first year (at least three times above market value) and incrementally more each year thereafter, reaching 35 cents after 20 years. That’s an additional 73 cents a month, or about $8.70, on the average home bill in the first year of the contract.

However, efforts to combat climate change and recent investments in near-shore wind projects point to a large and untapped market for floating technology that can be deployed far from shore.

“This is a bit of a race for the various designers like Dr. Dagher to prove out their technology, to prove that it’s the best,” said Wissemann, of the Mitsubishi subsidiary.

UMaine’s Advanced Structures and Composites Center will continue with design and engineering, research and development and post-construction monitoring. So far, the VolturnUS technology has been issued 43 patents and is being licensed by UMaine to New England Aqua Ventus for this project. Aqua Ventus will own and manage permitting, construction, assembly, deployment and ongoing operations.

If all goes to plan, platforms and column segments will be built in Brewer with turbine components assembled on the hulls in Searsport and then towed to the test site. A transmission cable just under 6 inches in diameter will be laid and carry electricity from the site to the mainland.

Following extensive permitting, deployment is expected by 2023.


“This will likely be the first project in the U.S. of commercial scale, if all goes according to schedule,” Dagher said. “When we first started this project almost 12 years ago, there were three technologies around the world, ours and two others. Today, there are 30 to 40 … so there’s a race.”

The four members of Maine’s congressional delegation released a joint statement Wednesday on the partnership announcement.

“For generations, Maine has been a national leader when it comes to using our natural resources sustainably to create jobs, protect our environment and power our economy,” Sens. Susan Collins and Angus King, and Reps. Chellie Pingree and Jared Golden said in the statement. “The University of Maine’s floating deepwater offshore wind project carries on that tradition. We have strongly supported UMaine’s development of the Aqua Ventus project. We are proud to see the project’s progress and applaud the $100 million public-private partnership launched (Wednesday), which will accelerate UMaine’s development of its innovative technology and create jobs. Maine’s offshore wind resource potential is 36 times greater than the state’s electricity demand, making this project so significant for Maine’s clean energy future.”

Wisseman said an important aspect of the project is to reach out to the fishing industry and treat the floating platform as something of a laboratory, to explore any environmental impacts and develop best practices for coexisting with traditional marine activities.

Gov. Janet Mills, who campaigned to replace LePage on a platform that included more focus on renewable energy, announced last year that Maine is joining New Hampshire and Massachusetts on a regional task force related to renewable energy activities in federal waters in the Gulf of Maine.

“This new public-private partnership joins world-class offshore wind developers and the University of Maine, and puts us on track to be home to the nation’s first floating offshore wind project, reflecting the major economic growth opportunity of the clean energy economy,” Mills said in a prepared statement. “I am pleased this project is moving forward, and encouraged by the partners’ strong commitment to work collaboratively with Maine fishermen to protect and support our traditional industries as we chart a greener future for our state.”

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