GE designs massive floating turbine to take wind energy into deep water

While offshore wind farms continue to play a growing part in the renewable energy mix, particularly in the US which recently approved its first major facility off the coast of Massachusetts, there remains a lot of untapped potential in the winds blowing across the world's oceans. GE is looking to unlock this potential through the development of massive wind turbines that can operate in deeper waters, by using advanced floating platforms that keep them steady as the waves crash violently around them.

GE Renewable Energy has been making some big moves in the world of offshore wind energy lately, unveiling its huge 12-MW Haliade-X turbine back in 2018, the world's largest. This 853-ft (260-m) tall behemoth features three of the longest offshore blades ever made, which are claimed to capture around 45 percent more energy than anything else on the market. There's already an even more powerful 14-MW version in the works.

The Haliade-X will be put to work at the world's largest offshore wind farm, Dogger Bank, off the coast of England, and will serve as the backbone for the aforementioned 800-MW offshore wind farm in the US, named Vineyard Wind. However, while unprecedented in size and power, the Haliade-X does have its limitations.

“With GE’s Haliade-X, the world’s most powerful offshore wind turbine built to date, we’re just beginning to tap into the future promise of offshore wind power in Europe, the US, and other parts of the globe, says GE's Rogier Blom, who is the principal investigator of the floating turbine project. “Today, these fixed-bottom wind turbines are limited to depths of 60 meters (200 ft) or less. With floating turbines, we would be able to dramatically expand the reaches of offshore wind power to areas with water depths of 60 meters or greater.”

Floating wind farms are starting to take shape around the world, with the Hywind farm off the coast of Scotland switched on in 2017. The facility features five turbines standing 253 m (830 ft) tall that together offer a capacity of 30 MW, while another proposed for California's central coast would become the world's largest at 765-MW.

But GE faces unique challenges in developing a floating turbine based on the gigantic Haliade-X. It is collaborating with marine design firm Glosten on a US$3 million venture under the US government's Atlantis (Aerodynamic Turbines Lighter and Afloat with Nautical Technologies and Integrated Servo-control) project, with the pair charged with designing a floating wind turbine that unlocks the grand potential of deepwater installations.

Offshore wind turbines in use today are anchored to the seabed with concrete or steel pilings. Floating turbines, on the other hand, are anchored to the seabed but via long tethers. GE and Glosten are drawing up a solution that uses the latter's Pelastar tension leg platform technology, while the former is developing the control systems to adjust those tethers on the fly to keep the turbine steady in turbulent waters.

“Designing a floating turbine is like putting a bus on a tall pole, making it float and then stabilizing it while it interacts with wind and waves," says Blom. "Doing this well is both a design and controls challenge.”

According to GE, the proposed floating turbine would have 35 percent less mass than current floating turbine designs. By paving the way for deepwater installations, the company says US offshore wind facilities could potentially generate more than 7,000 terawatt hours (TWh) per year, almost double the annual energy consumption of the US at 4,000 TWh.

The two-year development project kicked off in April last year, while GE presented its progress at the ARPA-E’s Virtual Innovation Summit this week.

Source: GE