U.S. industry confronts a new challenge: Hurricanes

Source: David Iaconangelo, E&E News reporter • Posted: Wednesday, October 31, 2018

How does a utility know if offshore wind turbines are hurricane-proof?

Build them and see.

That’s what Dominion Energy Inc. is proposing off the coast of Virginia, where company officials are asking regulators for permission to build a pair of turbines capable of spinning out a 12-megawatt stream of power.

Dominion is pitching the $300 million pilot project to demonstrate that turbines can deliver as expected — in stormy and tranquil times alike — before the company and its veteran partner, Ørsted A/S, pursue a commercial-scale wind farm in nearby waters.

Those lease areas could be far enough south to stand in the path of hurricanes, a phenomenon that’s still relatively new to the Eurocentric offshore wind industry.

The Atlantic coast and other storm-prone waters, especially those off Taiwan, represent important emerging markets, said Jeremy Firestone, a University of Delaware professor who focuses on offshore wind.

“Turbine manufacturers are going to develop their products to play in those markets. So I don’t foresee it as a big issue,” he said.

“Yes, there are threats to turbines off the coast of Virginia, but I don’t see any reason why that should prevent Virginia” from building, he said. “They just need to plan.”

Virginia’s State Corporation Commission (SCC) could make a decision this week on the project, also known as Coastal Virginia Offshore Wind.

The panel is likely to approve the Dominion project, working as it is in the shadow of a heavily supportive Legislature and governor.

Focus on resilience

But SCC staff is wary of what could happen if a big storm blows in.

At evidentiary hearings earlier this month, they probed Dominion representatives on how high waves could reach without damaging the turbines, with one official suggesting that shareholders — not ratepayers — should be liable for any storm-related damages.

Outside of a warranty period during which Ørsted, as a contractor, would be responsible for costs, “the ratepayers bear almost all the risk of a project design failure,” wrote Gregory Abbott, associate deputy director at the SCC.

Produced by a unit of General Electric Co. and deployed at the country’s only offshore farm in Rhode Island, the twin turbines were built for Category 5 wind gusts of 157 mph.

Planners also considered wave heights of up to 51 feet in their initial design, with even taller ones contemplated in scenarios occurring every 100 to 500 years, according to filings.

Abbott underscored the dangers of storm waves in particular, writing that although hurricane winds did damage once they hit land, waves “could be a greater hazard” for offshore wind farms.

In an interview, Walter Musial, who manages offshore wind research at the National Renewable Energy Laboratory, portrayed design challenges differently. Turbine structures and assessments of storm risks are drawn up according to site-specific combinations of wind, waves and seabed, said Musial.

“We have a pretty high confidence that we can design substructures that can survive the conditions of a particular site,” he said. “I don’t think you can go out and just try to find the biggest wave there is” and assume it should define the turbine’s design.

The focus of most hurricane-resilience work in recent years by the Energy Department, university researchers and institutions like New York state’s energy research agency has been cost.

“The key is to know what the external conditions are. Then it’s possible to design it,” Musial said. “And the question then becomes, is this increasing the cost?”

In the area around the wind project demonstration, Dominion officials said in filings, strong waves and storm currents could reshape the ocean floor beneath and around the turbines, exposing or damaging cables that transport energy to shore.

Researchers have warned that climate change could increase those types of risks along the Atlantic coast, but with less potential for damage compared with fossil fuel facilities. In fact, the offshore wind industry’s design standards were cribbed from the oil and gas industry, said Musial.

“They’re not inventing a new process,” he said. “They’re just adapting methods that have already been proven in the oil and gas industry.”