In May, federal officials gave final environmental approval for the nation’s first major offshore wind project, Vineyard Wind, to be located 14 miles off the coast of Massachusetts, and opened two areas off the California coast for wind development. However, while kilowatts could be flowing from the East Coast project as soon as 2023, harnessing power from Pacific winds will take significantly longer. A partnership of two U.S. companies is now working to address the challenges of installing 800-foot-high turbines in the Pacific, where offshore waters reach up to 2,000 feet deep.
The reason for tackling these challenges is easy to understand: federal officials anticipate those two areas off the California coast covered under Biden’s announcement will produce up to 4.6 gigawatts (GW) of electricity. According to U.S. Secretary of the Interior Deb Haaland, that’s enough to power up to 1.2 million homes. With the state set to lose the output of the 2.2 GW Diablo Canyon Power Plant in 2024, it needs new options for meeting its target of 100% carbon-free energy by 2045.
Because the continental shelf drops away so quickly off the West Coast, developers are looking to float their wind turbines, rather than establish a more solid connection to the ocean floor. At those depths, the more permanent structures planned for East Coast installations simply aren’t feasible. This makes Pacific coast wind farms a more ambitious undertaking than in Atlantic waters.
Floating wind farms do exist. Equinor, the Norwegian state energy company formerly called Statoil, developed the first major floating wind farm, the 30-megawatt (MW) Hywind Scotland, in 2017. The company is now developing an 88-MW facility in Norway’s North Sea waters, to power (somewhat ironically) offshore oil and gas platforms. However, with only 11 turbines, this installation—currently the world’s largest, according to Equinor—would be dwarfed by potential U.S. West Coast investors’ ambitions.
Onshore wind leader GE, Boston, has partnered with the Seattle-based engineering firm Glosten to develop a new approach to floating technology, partially financed under the U.S. Department of Energy’s Advanced Research Projects Agency—Energy (ARPA-E). The GE/Glosten effort falls under a program with an even mouthier moniker: Aerodynamic Turbines, Lighter and Afloat, with Nautical Technologies and Integrated Servo-control (ATLANTIS).
The two companies are now halfway through a two-year, phase 1 effort researching approaches to integrating the platform, tower, turbine and controls in a way that drives down the mass and cost of tension-leg floating wind turbines, using GE’s 12-MW Haliade-X turbines and Glosten’s PelaStar turbine-support structures. This design is borrowed from floating offshore oil rigs, and it incorporates a buoyant hull connected to anchors at the seabed using cable systems called tendons.
Ben Ackers, Glosten’s vice president, said the wind industry can borrow a lot from the floating oil platform industry, but wind developers have much tighter budgets.
“Oil companies can afford a relatively high capital cost per platform because of the high revenue produced from a single production platform,” he said.
Wind companies, however, earn less revenue per turbine and each wind farm requires dozens, if not hundreds, of units.
“That compels us to standardize and industrialize our platform designs,” he said. “This means designing highly optimized structures and driving down the cost of components through innovation and large-scale production.”
Of course, once they are designed, floating turbines will have to be installed, which poses its own challenges. To meet this need, Glosten is developing a purpose-built vessel, the PelaStar Support Barge, which will enable platforms to be assembled with turbines and their towers on land and transported out to the site. It also will provide stability during installation and maintenance. Other installation options the company is exploring include using temporary buoyancy approaches to allow assembled structures to be towed to a final location and a self-assembling structure that, Ackers said, “transits at the base of the tower and raises itself to the tower top when the platform is stable on its tendons.”
For the second phase of the ATLANTIS program, ARPA-E administrators plan to fund testing of floating platform designs in the open ocean. However, Ackers said his company intends to proceed with its own aggressive testing schedule regardless of how that joint effort pans out.
“Either with ARPA-E or through other opportunities, Glosten seeks to deploy a PelaStar demonstration by 2024,” he said. “Ultimately, the work will pave the way to making floating wind more attractive to developers and open the incredible wind resource available in the deep water of the North Sea, North Atlantic, U.S. West Coast, Japan and Southeast Asia.”