Floating Wind Turbines

Courtesy of University of Maine

A floating offshore wind turbine built by Maine Aqua Ventus

(Is the energy output from such an undertaking free and is it clean?)

There’s roughly enough wind off the West Coast to power all of the U.S. Alla Weinstein is determined to harness as much of it as she can. Weinstein is chief executive officer of Principle Power, a Seattle company that has developed a ballast system that buoys wind turbines so they don’t have to be bolted to the seabed. On Feb. 5, Principle received approval from the U.S. Department of the Interior to build a 30-megawatt floating wind farm off Oregon’s coast, the nation’s first in the Pacific Ocean.

Wind speeds are faster and more consistent at sea than on land. Companies seeking to take advantage of that were limited by the need to attach turbines to the ocean floor. Principle Power’s technology removes that constraint. It’s “what happened in the oil and gas industry back in the ’70s, when it moved from fixed foundations to floating foundations,” Weinstein says.
Fixed-foundation turbines require more permits. They’re also more likely to incite protests, such as those that have delayed the Cape Wind project off Massachusetts and a wind farm off Scotland that Donald Trump says will ruin the views from his golf resort there. Floating turbines, which are held in place by anchors, can be placed 20 miles offshore—“out of sight, out of mind,” as Weinstein puts it.
Principle installed a floating 2Mw turbine built by Vestas (VWS:GR) about 3 miles off the coast of Portugal in 2011, a project that may reach a total capacity of 150Mw. The company is also pursuing deals in the U.K. and Asia. The Oregon wind farm, with an estimated cost of $200 million, will consist of five 6Mw Siemens (SI) turbines about 15 miles off the coast and is expected to be hooked up to the grid via an underwater cable in 2017.

A 12Mw floating project is slated to begin delivering electricity the same year to Maine, where the public utility commission in January approved a plan submitted by Maine Aqua Ventus, a partnership among Emera (EMA:CN) of Nova Scotia, Cianbro of Maine, and Maine Prime Technologies, a University of Maine spinoff. The partners built and tested a one-eighth-scale model last year. The next step calls for placing two 6Mw turbines about 12 miles off Maine’s coast on platforms fashioned from concrete. (Principle uses steel.) The companies will save tens of millions of dollars because they won’t have to rent jack-up barges and cranes used to install fixed-foundation turbines, says Habib Dagher, director of the University of Maine’s Advanced Structures & Composites Center, who’s spearheading the project. Dagher envisions a future in which “every 20 years we can tow the unit back to shore and put a next-generation turbine on top of it.”
Walt Musial, a researcher at the U.S. Department of Energy’s National Renewable Energy Laboratory, estimates that there’s more than 900 gigawatts of offshore wind capacity along the Pacific coast of the U.S. That’s about the same as the country’s installed power capacity. The cost of deploying fixed-bottom turbines is about $4 or $5 per megawatt-hour, he says, vs. $6 per megawatt-hour for floating systems. The gap may eventually disappear. “We’re talking about single-unit prototypes that are still very early-stage,” Musial says. “It’s like the first flat-screen TV. It’s very expensive to build the first one.”

The bottom line: Floating turbines will reap some of the 900 gigawatts of wind capacity available off the Pacific coast of the U.S.