Diamond Offshore, RWE Renewables join Maine’s Aqua Ventus floating offshore project
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New England Aqua Ventus I Wind Project on Wednesday announced a critical joint venture between Diamond Offshore Wind, a subsidiary of the Mitsubishi Corporation, and global offshore wind giant RWE Renewables to develop the University of Maine’s floating offshore wind demonstration project off the coast of Maine.
Diamond and RWE will invest USD 100m to build the project and help demonstrate the technology at full scale.
The project will consist of a single semisubmersible concrete floating platform that will support a commercial 10–12 MW wind turbine and will be deployed in a state-designated area two miles south of Monhegan Island and 14 miles off Maine’s coast.
The floating turbine technology is considered a viable solution to building wind farms in deeper waters off the East and West coasts and has the potential to lead to a commercial-scale project placed in U.S. federal waters.
“We’re the first team in the U.S, to look at floating offshore wind at the University of Maine and the reason for that was the oil crisis a little over a decade ago, and at the time we started looking for other ways in the State of Maine to heat homes because we were very reliant on oil and close to three-quarters of us used heating oil at the time,” Dr. Habib Dagher, executive director of UMaine’s Advanced Structures and Composites Center and NEAV principal investigator, told New Project Media in an exclusive interview. “And at USD 4.00 a gallon, that became a big issue for Maine. A lot of communities were really at risk of losing their homes and losing their incomes just because they couldn’t pay those heating costs. Maine is a very rural state and the cost of gasoline is also very high for Maine residents because we tend to travel longer and more with our cars. So the plan that we started working on about 12 years ago was to electrify heating and electrify transportation by using essentially offshore wind.”
The demo project will further evaluate the floating technology, monitor environmental factors and develop best practices for offshore wind to coexist with traditional marine activities.
Construction, following all permitting, is expected to be completed in 2023.
After winning funding from the U.S. Department of Energy (DOE), the university worked with Maine-based construction firm Cianbro in 2013 to build and deploy a one-eighth scale prototype of its VolturnUS floating hull–the first grid-connected offshore wind turbine in the U.S.
The success of the project led to additional funding from the DOE to further advance the VolturnUS technology, which has been issued 43 patents to date.
“Maine has a very large offshore wind resource off the coast in the Gulf of Maine,” Dagher said. “If you look at a map and the offshore wind resource, as you travel north up the East Coast the winds get to be better and better, so when you get to the Gulf of Maine it’s one of the better offshore wind resources in the U.S., only rivaled by the West Coast. Most of this resource exists in deep water off the coast of Maine so if you are three nautical miles off the coast, you are in about 300 feet of water so you really can’t use fixed-bottom turbines. That’s why we’re focused on floating turbine technology. And that’s not just true for Maine but if you look off the coast of Massachusetts, over half of that resource is also in deep water that would require floating technology.”
Each floating turbine, or hull, is held in position in the ocean by three marine mooring lines anchored to the seabed, with the electrical generation connected by subsea cable to the Maine power grid on shore.
“We towed it out to sea off the coast of Castine and this became the first offshore wind turbine connected to the grid in the U.S. so history was made back then,” Dagher said. “It was almost a 12-hour tow. Then we left it in the water for a year and a half with about 50 sensors onboard that actually told us how it performed. It did so well that we were able to go ahead and with a grant from the DOE to build a full-scale version of this hull. The next phase of the project is going now from the one-eigth scale to full size. It’s a very sizable turbine and would be the biggest floating turbine planned for installation. Because it was a one-eighth scale version relative to its size, it saw very big waves very quickly. I tell everybody that the best way to speed up time is to reduce scale, and this is what we did.”
Creating local jobs
An immediate priority for the new development team is to engage with the fishing industry, other maritime users and coastal communities on how the project can boost Maine’s economy.
“We embarked on this research to find technologies that would cost-effectively bring some electricity back home,” Dagher said. “The idea was to develop a hull that can actually be fabricated fully and locally. A lot of communities who are interested in offshore wind would like to produce these components locally so we embarked on this mission to develop a low-cost technology that can be fabricated locally and create local jobs.”
The project is expected to produce more than USD 150m in total economic output and create hundreds of Maine-based jobs during the construction period.
“What’s unique about the hull is it’s built in modules–that’s what the patents allow us to do,” Dagher said. “Basically the hull is made with hollow cans and hollow boxes that you can fabricate locally. It looks like a bridge upside down. It’s built like you build bridges, and we have a lot of contractors who know how to build concrete bridges across the country. And that’s why this technology is so unique; we can build it tomorrow. That same project can be replicated across the country.”
Floating technology could also potentially mitigate multiple siting conflicts.
“One advantage of floating wind is you actually place these turbines offshore so they’re not visible from land,” Dagher said. “You have the ability to do that and typically the farther you go offshore, the better the wind is. You have more places to put them if you can go 20 or 30 miles offshore and you have less conflict with the fishing industry. We have the tools with floating to reduce those impacts and work with those communities, and it gives us more real estate to explore. Of course, we can’t eliminate conflict, but we can reduce it significantly.”
Image courtesy of University of Maine