How futuristic floating wind turbines might ride the waves

GE shared some new details today of a concept that might advance the development of futuristic floating wind farms. Floating turbines are engineering marvels — or nightmares, depending on how you see it — that could make massive swathes of deep ocean available to offshore wind development.

Make massive swathes of deep ocean available to offshore wind

While they hold a lot of potential, the floating behemoths have so far been too costly to deploy at commercial scale. And because they’re floating, they also face a barrage of technical challenges that turbines fixed to the seabed don’t have to weather. GE hopes to solve some of those problems through advanced turbine controls that it’s developing alongside consulting firm Glosten. They’re pairing this with their largest turbine model, which is nearly as tall as the Statue of Liberty and Washington Monument combined.

GE received a $3 million award from the US Department of Energy to support the two-year project, which started last year. If the company can prove, through modeling and simulations, that its design will work, then it might move forward with its partners on the project to build a prototype. Today, they’re revealing some details of their design during an “Energy Innovation Summit” hosted by the DOE.

Designing a turbine that can float gracefully on the water is like “putting a bus on a tall pole, making it float and then stabilizing it while it interacts with wind and waves,” according to Rogier Blom, GE’s principal investigator for the project.

“Putting a bus on a tall pole, making it float”

The turbines themselves are essentially the same as other turbines fixed to the seafloor. The big differences are the design of the platform holding it up and the controls used to maneuver them on rough open ocean. GE is working to couple the design of an existing 12MW turbine and platform with automated controls so that they can work together in a more streamlined way. The controls, built-in sensors and computers, improve how the turbine responds to wind and waves.

If these controls are successful, the floating turbine could automatically adjust itself to catch strong gales without tipping over. That would ultimately maximize their power output, making them more profitable. Floating turbines without more advanced controls need to be bulkier so that they can stand up to surf. But with a smarter design, GE aims to reduce the platform’s mass by more than a third compared to other designs for floating turbines — which would ultimately cut down on costs.

GE is using a so-called “tension-leg platform” that’s anchored to the seabed with adjustable “tendons.” Its new technology would be able to sense gusts of wind and swells in the ocean and, in real time, adjust the length of the tendons accordingly so that the platform can smoothly ride the waves. Blom describes the process as “see, think, do.” The control system’s sensors, for example, detect a change in wind speed, determine how that change affects the turbine, and then make adjustments to respond.

Tension-leg platforms are “innovative” and one of the most stable platform designs, according to Walt Musial, a principal engineer who leads offshore wind research at the National Renewable Energy Laboratory (NREL). But it’s also very difficult to install, and a prototype hasn’t even been demonstrated yet with a full-scale offshore wind turbine on top (although similar technology has been used for offshore oil production), according to Musial. Then again, everything about floating wind farms is still pretty novel. There are only a handful of floating wind turbines operating in the world and no commercial-scale wind farms.

That could soon change. Musial forecasts the first commercial-scale project to come online, probably in Asia, in just a few years. Developing advanced controls, as GE is attempting, plays a big role in making that happen, he says.

They can move far away enough from shore to potentially satisfy coastal residents

“We are excited about this project because this could be a common enabling technology to tap into [a majority] of offshore wind resources,“ says Blom. Offshore wind designs are currently limited to waters shallower than 60 meters deep. That puts 60 percent of US offshore wind resources out of reach of fixed offshore turbines. But those resources could be developed with floating farms, according to NREL.

There are other advantages to floating wind farms. They can move far away enough from shore to potentially satisfy coastal residents concerned about how turbines might affect fishing, birds, or seaside views. They also don’t disturb the seabed — except for anchors used to moor the platform. That solves yet another problem that’s stymied offshore wind development: a shortage of specialized ships needed to install turbine foundations.

There’s been skepticism in the past about whether floating turbines can develop fast enough and bring costs down to a point where they can really take off. They’re also competing with their seafloor-fixed counterparts that are quickly advancing into deeper and deeper waters.

“We shouldn’t underestimate the creativity of the fixed offshore wind industry, because they are also pushing the boundary,” says Po Wen Cheng, head of wind energy at the University of Stuttgart’s Institute of Aircraft Design. When he started in offshore wind research some 20 years ago, people didn’t think traditional turbines could be installed in waters deeper than 20 meters. They’ve since smashed that limit. But in a race to develop enough renewable energy to stave off the climate crisis, there may be enough room yet for both floating and fixed designs to take to the seas.

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