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Equinor considers driving huge pilings into LI seabed for wind turbines

Equinor is considering supporting massive wind turbines like

Equinor is considering supporting massive wind turbines like these, located in the Baltic Sea, by driving huge pilings into the seabed off the Long Island coast.  Credit: AP Images/Bernd W'stneck

When New York State in 2019 awarded a multibillion-dollar contract to Norwegian energy giant Equinor to build wind turbines off the Long Island coast, one critical element of the award was its planned use of giant concrete foundations.

That choice would lead to hundreds of jobs, most of them in the Albany area where the components would be made, and provide "tremendous environmental advantage, minimizing risks to fish and wildlife," according to the state that year.

But Equinor has yet to fully commit to using those "gravity-base structures" for the project, or for another larger wind farm to be constructed adjacent to it. Its recently filed construction and operation plan provides a detailed review of an alternative option: using giant monopiles that are driven into the seabed from a pile-driving barge.

What to know

  • The contractor Equinor is hedging on a seeming commitment from 2019 to use concrete foundations for a wind farm off Long Island, raising an alternative: giant monopiles driven into the seabed.
  • The New York State Energy Research and Development Authority left open the prospect that multiple options were available for Equinor to complete the project.
  • A 2019 study prepared for federal regulators by the Anderson Cabot Center for Ocean Life raises concerns that pile-driving during wind-farm construction could harm endangered whale species.

In the same report, Equinor noted that a gravity-base structure "under environmental forces is more sensitive to weak horizontal layers across the foundation footings." And it says that the concrete foundations have already been "removed from consideration" for use in an offshore substation that's part of the project because of "design challenges."

Asked this week whether the concrete foundations, which act much like heavy backyard umbrella stands to keep the turbines upright in stressful offshore conditions, were still in the cards, an Equinor spokeswoman hedged.

"We aim to use the best foundations for our project possible — from an environmental, operational, construction and long-term commercial standpoint," spokeswoman Lauren Shane said in a statement. She noted the construction plan "contemplates both gravity-base structure (GBS) and monopile foundation types. We continue to assess the viability of both types ... as we move toward finalizing the project design."

Using pile-driven monopiles has one significant advantage over gravity-based concrete foundations: lower cost. But it would also mean the 600 to 800 promised jobs making the giant concrete structures in the Albany region could be significantly reduced or eliminated.

The New York State Energy Research and Development Authority, which formally awarded the contract to Equinor over some 18 other projects, in a statement last week also left open the prospect that multiple options were available for Equinor.

"NYSERDA expects Equinor will make the best choices to execute a Construction and Operations Plan that is the most efficient, cost-effective and safe for marine life," NYSERDA marketing vice president Kate Muller said in written responses.

She added that "It has always been understood that specific foundation positions might not be feasible" for use of gravity-base foundations.

Were Equinor to move to all pile-driven turbine structures, Muller said it would not reduce other financial commitments made by the company, including "obligations for the delivery of approximately $792 million in in-state spending and economic development."

Asked if the state would consider the impact of pile driving on whales and other sea life, Muller said the agency is "committed to working with the offshore industry, industry experts, and stakeholders to ensure New York’s offshore wind projects are cost-effectively and responsibly built for the benefit of New Yorkers and the environment."

Equinor had been considerably more certain about its foundation plans at conferences and presentations since winning the award in a ceremony with former Gov. Andrew M. Cuomo in 2019. At an offshore wind-power conference at the SUNY Maritime College later that year, gravity-base foundations were the only option discussed. The presentation included artists’ renderings of ships towing the foundations down the Hudson.

In its recent construction plan filed with the federal Bureau of Ocean Energy Management, Equinor has excluded gravity-base concrete foundations for use with an offshore substation that sits among the turbines, noting the "operational challenges" associated with boat landing and "accommodation of the crew transfer vessel."

As for the turbines themselves, the report notes that a concrete foundation "requires the upper soil layers to have the strength to sustain the heavier load. The surface may require improvements such as a separate gravel pad under each concrete foundation "to support distributing such a load and stabilizing installation," it said.

Pile-driving a monopile for the turbines avoids those issues, the report noted. Empire has already studied the "drivability" of the seabed. It found that driving a 246-foot monopile into the ground would require as many as 3,506 "blows" of a pile-driving hammer, and as few as 626.

A 2019 study prepared for federal regulators by the Anderson Cabot Center for Ocean Life, concluded, "There is enough evidence to suggest that pile‐driving around wind-farm construction has the potential to harm endangered whale species."

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