URI researchers awarded $750K grant for research on floating wind turbines
The Biden administration has set a goal of deploying enough offshore wind turbines to produce 30 gigawatts—enough to power tens of millions of homes—by 2035. Key to that strategy is the development of floating wind turbines that can be built in vast areas of deeper water.
Backed by a U.S. Department of Energy grant, a team of University
of Rhode Island researchers is working with colleagues at the University of
Maine to develop a remote sensing and computational system to control the
motion of floating wind turbines in irregular ocean conditions. The system
would maximize energy production and extend the turbine’s useful life.
The $750,000 grant was provided through the Department of Energy’s
Established Program to Stimulate Competitive Research (EPSCoR) program, part of
$33 million in awards announced recently to support 14 clean-energy research
projects. The URI project began in 2021 with an initial $1.245 million EPSCoR
grant.
The vast majority of offshore wind turbines around the world are
secured to the seafloor with fixed foundations, such as the turbines off Block
Island. The cost of installation of those turbines limits them to coastal
waters of up to a depth of about 200 feet. However, floating turbines allow for
the use of deep-water areas, which make up two-thirds of America’s offshore
wind energy potential, according to a 2022 White House fact sheet.
Stephan Grilli, URI professor of ocean engineering who leads the URI project, says vital to the development of floating wind turbines on a commercial level is the ability to control the movements of turbines to optimize operations.
With the grant, URI researchers are developing a wave remote sensing system that combined with real-time control can correct the movement of the turbines in unpredictable seas and high winds, improving power production, reducing fatigue on the structure, and optimizing operations.
“The principle is if the turbine wants to go to one side, you need
to have a restoring effect to move it to the other side,” he said. “This is a
critical technology that would make large scale deployment of floating wind
turbines possible. It’s all about cost. To reduce the cost of energy, you need
to reduce the cost of the structure and increase energy production. Active
control achieves those two goals.”
The turbines, soaring up to 250 meters above sea level and
weighing around 500 tons, sit on floats anchored to the seafloor. They are very
top heavy and extremely susceptible to fluctuating waves and other conditions,
Grilli said. Wave loading can bend the structure many times, reducing the
turbine’s life. Turbulence can also affect the turbine’s blades and reduce
energy capture.
The system researchers are working on using LIDAR, a remote
sensing method that uses lasers to measure variable distances, to record wave
measurements a couple of hundred yards from the turbine. Data are fed to a
numerical model, which propagates the wave conditions to the turbine, faster
than real time, Grilli said.
A digital twin, which is a computational model of the turbine
behavior, predicts the movement of the turbine given the forces from waves and
wind, triggering measures to right the structure—such as shifting a solid mass
or water ballast, or pulling on the anchors that secure the turbine to the
seafloor, or changing the pitch of the turbine’s blades.
With the new two-year grant, URI researchers and their graduate
students plan to build and test the LIDAR system, which includes a wave
reconstruction and forecasting algorithm. Plans are to first test it in
Narragansett Bay. Near the end of the grant, the system will be tested in
concert with a 20-meter-tall scale model of a floating turbine at the
University of Maine’s field testing facility.
“We’re going to build a floating platform separate from the wind
turbine with a computer system that’s going to predict the waves and
communicate that to the turbine to see if we can improve control of the
turbine’s movements,” he said. “That’s the goal of the new project.”
There are fewer than two dozen floating turbines around the world.
But with the lack of sufficient sites suitable for turbines with fixed
foundations on both U.S. coasts, floating turbines are needed to reach the
president’s goal for wind energy—which includes 15 gigawatts from floating
turbines by 2035.
While the West Coast has a narrow continental shelf that forces
turbine development to deep water, the East Coast is crowded with many
activities—navigation, fisheries and conventional offshore windfarms, Grilli
says.
“Once we have installed the approximately 10 farms that are
planned or in construction on the East Coast, you’re going to have to move to
deeper water,” he said. “Deep water means floating offshore wind turbines.”
In addition to Grilli, URI researchers involved in the project
include ocean engineering professors Jason Dahl, Annette Grilli, Reza Hashemi,
Brennan Phillips and Bradford Knight. The University of Maine team is led by
Richard Kimball, professor of mechanical engineering, and includes professors
Babak Hejrati and Kimberly Huguenard.
The project will also help train future workforces for offshore
wind and the blue economy. Graduate and undergraduate students were involved in
the initial work and will be a part of the new project, Grilli says.
“The blue economy is extremely important for Rhode Island. The
state has already demonstrated we were ahead of the curve with Block Island and
we are also the staging area for other offshore wind farms,” he said. “In the
Department of Ocean Engineering, we want to further develop our expertise in
that direction, including our teaching. We are working on a minor in wind
energy and are also developing a graduate certificate in offshore wind.”