Green sand threatens Biden’s offshore wind ambition

By Heather Richards | 06/24/2024 06:37 AM EDT

A mineral called glauconite is disrupting plans to install wind turbines at several sites off the U.S. coast.

Photo collage illustration of offshore wind turbines and a hand with a magnifying glass over glauconite sand

Illustration by Claudine Hellmuth/POLITICO (source images via iStock and Wikipedia)

A green mineral scattered along the Atlantic Ocean’s seafloor is the latest hurdle for President Joe Biden’s plan to jump-start the offshore wind industry.

Glauconite is sediment that resembles the green sand in a fish tank. But if pounded by pile drivers, it shatters to form a claylike layer.

Monopiles — hollow steel tubes driven deep into the seafloor to support turbine towers — often cannot be hammered through the thick paste, cutting off the cheapest and most widely preferred foundation for the first U.S. offshore wind farms.


“It’s almost like magic what happens when the monopile is driven through it,” said George Hagerman, an offshore wind expert at the Department of Energy’s National Renewable Energy Laboratory. “It all of a sudden becomes very, very, sticky, almost like plaster.”

Identified in several offshore wind lease areas in the north Atlantic, the mineral poses a growing hazard to offshore wind projects that already face high costs and razor thin margins. At least four wind lease areas off the coast of New England and New York — Beacon Wind, Empire Wind, New England Wind and Sunrise Wind — have all have grappled with glauconite.

The glauconite challenge piles pressure on the Biden administration, which has been falling behind on its goal to power 10 million homes with offshore wind power — that’s roughly 30,000 megawatts of offshore electricity — by the end of the decade because of economic headwinds facing the industry.

The Interior Department declined to comment on glauconite.

But Interior Secretary Deb Haaland said at a June 7 event in Annapolis, Maryland, that her department was “working around the clock to transition to clean energy.”

“Our administration has been laser focused on making what many of us thought impossible — a thriving and sustainable domestic offshore wind industry from coast to coast,” she said.

The Bureau of Ocean Energy Management, which oversees offshore energy development, declined an interview on the mineral. In a paper BOEM released last year, the bureau said that developers will “inevitably encounter” glauconite in their lease areas in the Atlantic Ocean and its properties pose “significant risks” to building offshore wind farms.

Several offshore wind developers have dealt with glauconite by eliminating turbine positions, a cheaper option than pioneering new drilling techniques or finding alternative foundations — but one that can cut down on a wind farm’s power output.

Moreover, with the scale of glauconite unknown, avoidance is not seen as a long-term solution. Developers and federal agencies are scrambling to learn more about the mineral, where it is deposited and how to put turbines in it.

“Developers [were] being very conservative and just eliminating positions that look like they are at high risk. But that’s turning into a lot of turbine positions,” said Hagerman, who is also a senior scientist at the Center for Coastal Physical Oceanography at Old Dominion University.

The U.S. Geological Survey is compiling all documented references of glauconite offshore, with plans to release a report and geographic information system (GIS) map later this year to help address a significant data gap about where the mineral exists. Developers are also researching pile driving in glauconite sands, an initiative led by the Norwegian Geotechnical Institute.

Even as researchers gather new information about the green sand, it’s stoking frustration with officials trying to keep turbines out of some fisheries. Glauconite’s presence in several cases has restricted developers’ ability to avoid fish habitats.

“It kind of feels like there’s not the flexibility to use fewer turbines, or to not build in certain parts of the lease areas,” said Julia Beaty, a fishery management specialist at the Mid-Atlantic Fishery Management Council, of glauconite’s ripple effect. “There’s a push to build out as much as possible to create as much electricity as possible.”

Tracking glauconite

USGS says it plans this year to finish compiling available data on glauconite deposits — a project it’s doing in collaboration with the Bureau of Safety and Environmental Enforcement — including in existing and future wind areas.

The last time it did a comprehensive analysis that identified the location of offshore glauconite was in the 1960s, when the U.S. government tasked the survey with characterizing much of the nation’s offshore continental shelf. In a 1972 report, USGS identified deposits of the green sand in samples taken from Nova Scotia down to New Jersey.

Laura Brothers, a marine geologist with the survey leading the glauconite synthesis study, said U.S. offshore territory is large and much of it has not been characterized.

USGS is also identifying other hazards to renewable energy along the Atlantic coast in its study and digital map. But even with known glauconite data compiled in one place, there will not be a complete picture of where glauconite is present offshore, Brothers said.

“We are only reporting places that glauconite has been published to exist, has been identified specifically. And so, in that way, our report is a minimum,” she said. “But a desktop study is an important place to start to see what’s out there.”

Glauconite's presence isn't only an engineering or cost challenge for developers. It has stoked conflict between wind development and fisheries.

When the BOEM considered placing a buffer between Equinor’s Empire Wind 1 and Empire Wind 2 offshore wind projects off the coast of New York, the goal was to increase access for fishermen in the area.

But the presence of glauconite potentially eliminates up to 22 locations for potential monopiles in that lease area, making the fisheries buffer zone essential real estate for turbines, according to federal records.

Similar stories have cropped up with other projects.

BOEM considered multiple alternative layouts for Ørsted’s Sunrise Wind that would have cut turbine locations to reduce the impact to fisheries, but glauconite made part of the lease area impossible to develop, according to federal documents. If Ørsted cut turbines for fishing habitats, the project would not be able to produce 924 megawatts of power — the amount Sunrise was contracted to provide to the New York grid.

Glauconite’s occasional restrictions on alternative turbine layouts has frustrated fisheries experts because it is sometime discovered and disclosed in the middle of environmental reviews.

Glauconite is a “glaring example” of why fishing mitigation proposals need data early in the process to be useful, said Beaty with the fisheries council, which advises NOAA Fisheries on fishing habitats. Experts are making recommendations unaware of what is actually feasible in a wind project area, Beaty said.

NOAA Fisheries has similarly sought earlier identification of glauconite in lease areas.

“We understand that the presence of glauconite is creating construction feasibility issues for some projects and the collection of geotechnical cores necessary to identify these constraints is occurring late in the process,” NOAA wrote in a letter to BOEM in April 2023 about the draft environmental review of the SouthCoast Wind offshore wind project — formerly known as Mayflower Wind.

“It is unclear if these studies have been conducted for this lease area and how the results of these surveys may affect construction feasibility or foundation selection,” NOAA said.

NOAA said in a statement to POLITICO’s E&E News that it recommends developers do surveys of the sea floor before they propose construction and operations plans to BOEM. That way, the information will be considered during BOEM’s draft environmental review process before a project is approved.

Rebecca Ullman, director of external affairs for SouthCoast Wind, would not verify if there was glauconite in the SouthCoast lease area off the coast of Martha’s Vineyard, Massachusetts. But she said the project's construction would "proceed as planned."

"Based on the site characterization data collected, we have designed our project to best suit the seabed conditions," she said in a statement to E&E News.

In a statement, BOEM noted that developers are responsible for surveying lease areas for potential hazards and reporting that to BOEM.

“If glauconite is detected as part of these surveys, the lessee is responsible for reporting and identifying how it will be addressed via mitigation measures,” the agency said in a statement.

Once a project’s construction and operations plan is submitted to BOEM, the agency said it then vets mitigation measures proposed to deal with glauconite or other hazards.

E&E News reached out to all of the companies with known glauconite in their lease areas; the presence of the sediment in those areas was confirmed through developers’ public filings to BOEM and a public records request from The New Bedford Light. All but Beacon Wind responded with assurances that they are managing the mineral without damage to their project outlook.

Craig Gilvarg, a spokesperson for Avangrid, said the company has considered potential pile refusals due to glauconite in its New England Wind 2 project area — formerly known as Commonwealth Wind. But he said the company remains confident it can work around the mineral to "fully mitigate any risk associated with glauconite."

"Avangrid does not anticipate the need to remove any positions within the lease area," he said.

Denmark-based Ørsted said glauconite is not a problem for any of its Atlantic leases, so far. Spokesperson Maddy Urbish said the company is doing survey work this year that will examine the sea floor for hazards like glauconite in Lease Area OCS-A 0500, also called Bay State Wind, off the coast of Massachusetts.


Though glauconite may not be a well-known mineral, it has a history of thwarting construction projects — and it has inspired workarounds the wind industry is now studying.

Ahead of a road construction project in Antwerp in 2015, Belgian researchers found they could successfully predrill holes before pile driving in glauconite sands, according to BOEM’s report. The offshore agency also said the Belgian study “was conducted on a river and cannot be directly translated to offshore deep-water construction.”

European countries have encountered clay in tunneling projects under estuaries that pose similar challenges to glauconite sands. They’ve developed special cutting heads to penetrate in those soils, said NREL's Hagerman.

Offshore wind developers in the United Kingdom have also used something called the "drive-drill-drive" approach when hammering monopiles into clay-like material. Also called “relief drilling,” this strategy periodically stops hammering to remove mud from the core of the pile with a massive drill.

The drive-drill-drive approach hasn’t been used in glauconite sands, so it would require testing for wind developers in the United States. Monopiles have a threshold for how much pounding they can take before weakening, so they can’t simply be hit with a larger hammer in soils with glauconite, Hagerman said.

How deep and concentrated the glauconite sediment lies also affects whether it will reject monopile pile driving, according to BOEM’s report in 2023.

Monopile foundations are driven between 80 and 200 feet into the ocean floor, while piled jackets — another common foundation type with thinner piles — go between 200 and 300 feet deep. If glauconite is concentrated deep enough under the sea floor, shallow foundation designs can avoid the problem altogether.

This year, BP’s Beacon Wind project was approved to test suctioning monopiles to the seafloor in its lease area due to the presence of glauconite. Suction buckets have been used commercially for years and are seen as perhaps the most viable alternative to monopiles in glauconite sands, but they do have a larger footprint on the seafloor, according to BOEM.

Hagerman said one challenge with suction buckets would be sourcing the foundations in the United States. The industry already faces supply chain congestion domestically, with limited manufacturing dedicated to offshore wind.

Developers are currently relying heavily on Europe for their supply chain. But as offshore wind ramps up globally, competition for offshore wind parts will ramp up. The U.S. will not be able to rely so heavily on imports, he said.

“It's definitely not an insurmountable problem,” Hagerman said of dealing with glauconite. “Necessity is the mother of invention. So, we innovate.”

Correction: A previous version of this story incorrectly termed an alternative monopile installation technique as “drill-drive-drill.” It is “drive-drill-drive."