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Wind turbines and radar mix poorly  

Credit:  By Rich Saltzberg | The Martha's Vineyard Times | August 21, 2019 | www.mvtimes.com ~~

As budding offshore wind development brings the U.S. to the brink of a new chapter in energy production, questions remain as to how radar interference caused by wind turbines will be diminished or eliminated.

Vineyard Wind’s 84-turbine wind farm, slated for an Atlantic lease area about 15 miles south of Martha’s Vineyard, effectively had the rug pulled out from underneath it August 9, when the Department of the Interior announced the Bureau of Ocean Energy Management (BOEM) would hold off signing a Final Environmental Impact Statement (FEIS) and re-examine potential impacts posed by the project. Radar was not specifically cited as something the feds would take a second look at. However, weather and aeronautical radar are all well-documented as being adversely affected by wind turbines, and a handful of studies show marine radar is also hampered by wind turbines. Fishermen who spoke with The Times said they already work in an inherently dangerous industry, and offshore radar interference has the potential to exacerbate that danger.

Technological measures to lessen radar interference from turbines are being researched and slowly implemented in the U.S. and Europe. However, none appear to be folded into the construction plans for Vineyard Wind. In its Revised Navigation Risk Assessment, Vineyard Wind borrowed from a 2009 U.S. Coast Guard review for the never-realized Cape Wind project, and stated for its own project, “impacts to radar should not negatively impact a mariner’s ability to safely navigate in the [wind development area]; even so, Vineyard Wind will work with stakeholders to identify potential mitigation measures, as necessary.”

In a March 1 letter to BOEM, Commander Sector Southeastern New England Coast Guard Chris Glander indicated he wanted a deeper look into the problem. “We recognize that potential impacts to marine radar continues to be of concern to mariners,” Glander wrote. “Radar impacts are a function of numerous issues, including turbine height and size, proximity to other towers, weather, atmospherics, shipboard radar quality, radar operator proficiency, target size and number, etc. Both the [Draft Environmental Impact Study] and [Navigation Safety Risk Assessment] mention projected radar impacts only briefly, though Vineyard Wind has committed in both documents to ‘work with stakeholders to identify potential mitigation measures, as necessary.’”

Glander went on to write that the Coast Guard may make the same recommendation for Vineyard Wind that it did for the Block Island Wind Farm, a research analysis indicating whether the turbines “produce radar reflections, blind spots, shadow areas, or other effects that could adversely impact safety of navigation.” If there are negative impacts to marine radar, Glander wrote, Vineyard Wind should recommend how to remedy them. If such remedies are necessary, he wrote they should be “funded by Vineyard Wind.”

The Block Island study was conducted by British defense contractor QinetiQ in 2015. In several different radar modeling simulations using X band and S band marine radar on various-size vessels, the study found incidents of various forms of clutter, among other radar impacts. The study defined clutter as “unwanted radar returns … radar echoes from wind turbines are clutter because they have the potential to affect the detection of other vessels.”

The danger of clutter, several fishermen told The Times, is that in certain instances it could lead to a collision.

When asked recently about Vineyard Wind’s radar-interference mitigation efforts, spokesman Scott Farmelant emailed, “Vineyard Wind has been working closely with the Coast Guard to ensure safe navigation through the turbine area, including addressing radar issues, if any, in an appropriate manner.”

The Coast Guard has been tight-lipped about research and policy development it has undertaken relative to radar interference from offshore wind turbines.

Michele DesAutels, a civilian at work in the Coast Guard First District building in Boston, is the lead person on the matter for the Coast Guard, Petty Office Nicole Groll told The Times, but said DesAutels wasn’t available to the press.

Full fed press

The Coast Guard is far from the only federal agency looking into wind turbine radar interference. A working group composed of the Department of Defense, the Department of Energy, the Department of Homeland Security, the Federal Aviation Administration, and the National Oceanic and Atmospheric Administration was established in late 2014 to tackle the problem. BOEM later joined the group. The U.S. Coast Guard joined in April of this year.

Known as the Federal Interagency Wind Turbine Radar Interference Working Group, it produced a mitigation strategy document in 2016 that outlined the problem of radar interference and a lengthy to-do list to solve those problems. One author of the document, retired Air Force Lt. Colonel Bryan Miller, told The Times the group has found no foolproof solution to certain types of radar interference created by wind turbines. This was not for lack of trying. Among other resources, the working group has tapped Sandia National Laboratories and MIT Lincoln Laboratory for solutions, Miller said. Both labs also have radar achievements under their belts, with Lincoln by far the leader, having developed the SAGE radar system, a key element in U.S. Cold War defense.

Miller said one of those labs came up with a promising “temporary fix,” but in the end, “it didn’t work out as well as we hoped.”

Most of the working group’s study involves land-based wind turbines, but that’s changing – of offshore wind turbine interference, Miller said, “We’re getting into that realm.”

In its strategy introduction, the working group pointed to a 2011 White House report that outlined the problem of radar interference.

“Wind turbines have significant electromagnetic reflectivity, as large structures and blades cause large and numerous Doppler returns because of their motion relative to the affected radars,” the introduction states. “In May 2011, the White House Office of Science and Technology Policy completed an internal decision-making study at the request of the National Security Staff that found that wind turbines were interfering with government radars used for national defense, national security, aviation safety, and weather forecasting ‘by creating clutter, reducing detection sensitivity, obscuring potential targets, and scattering target returns. These effects on radar systems tend to inhibit target detection, generate false targets, interfere with target tracking, and impede critical weather forecasts.’”

Miller, who noted his last job for the U.S. Air Force at North American Aerospace Defense Command (NORAD) was to “protect long-range radar from the impacts of wind turbines,” said unsurprisingly, some of the research into radar interference is classified. He said the British have also been at work on the subject, and pointed to Project Green Blade. Largely an effort to mitigate wind-farm impacts on aeronautical radar, the project features a type of radar called holographic radar, which is purportedly immune to radar interference problems associated with wind turbines.

This holographic radar is manufactured by British contractor Aveillant.

“The problem first raised its head in the U.K. around 20 years ago as the drive for green energy turned peoples’ attention to using wind power,” Aveillant sales and marketing manager Richard Lawrence emailed. “In the U.K., many of the best offshore wind-farm sites are along the eastern shoreline from the Wash up to the Scottish east coast. Unfortunately, that’s also where most of our radars are looking (both civil and defense). The problem is that wind turbine blades represent a large reflector to radar, so you effectively get a very ‘cluttered’ area in which it’s very difficult to see aircraft. The problem is made worse because traditional radars only return information on the range and bearing of the target, not height. This means clutter at low level effectively masks all targets in a vertical column above that low-level clutter. This results in lost or broken tracks, meaning you may lose continuity with aircraft, making separation and surveillance problematic.”

Lawrence wrote that Aveillant’s radar can detect targets in three dimensions: range, bearing, and height.

“This means that it can not only detect targets above the surface-level clutter created by the wind turbine blades, it can also differentiate the targets based on their height,” he wrote.

Lawrence likened traditional radar to a flashlight beam rotating in a dark room and holographic radar to essentially switching on the lights to that room.

Based on the description, David Bodine, a researcher at the University of Oklahoma’s Advanced Radar Research Center, said it applied principles of phased-array radar, which is common in military vessels and aircraft. By and large, he described such radar systems as large and costly and an unlikely candidate for fishing vessels. Like holographic radar, phased-array radar doesn’t suffer effects from wind turbines, he said. At the University of Oklahoma, another type of radar, called polarimetric atmospheric imaging radar, or PAIR, is under development.

“It will be a C band radar (between S and X bands),” Bodine emailed. “[I]t is primarily for studying severe storms such as tornadoes, but also hurricanes. It will have the ability to eliminate wind-turbine clutter.”

The Times asked the Massachusetts Department of Transportation’s Aeronautics Division if they had any reservations about flights to and from the Vineyard being adversely affected by Vineyard Wind, and they emailed that MassDOT Aeronautics hasn’t commissioned any studies about potential radar hazards from Vineyard Wind. However, “Aeronautics does not expect any potential danger to aircraft on approach to or departure from Massachusetts airports due to wind-turbine radar interference from the Vineyard Wind wind farm.”

QinetiQ, the contractor that conducted the Block Island Wind Farm study, helped create what it describes as a “stealth wind farm” in France. Using radar-absorbing or stealth material, the company, according to a case study, reduced the radar interference of 35 wind turbines by 99 percent.

“That’s going to be a problem,” Vineyard Haven fisherman Jeff Canha said of Vineyard Wind. While not in opposition to the wind farm, Canha said, he thinks the area will be off-limits to fishing vessels. That’s an opinion shared by several fishing advocates, including Long Island Commercial Fishermens’ Association’s Bonnie Brady, Meghan Lapp of Rhode Island’s Seafreeze, New Bedford scalloper Eric Hansen, and Rhode Island Fishermen’s Alliance president Richard Fuka.

Lapp said she believes marine insurers will decline to cover boats that enter Vineyard Wind because of the radar risks, among other perils. She pointed out many fishing vessels’ insurers, for example, won’t allow them to transit Woods Hole because they deem it too treacherous. She said she believes similar logic may be applied to the wind farm, upon its erection. Hansen said his boat is among those prohibited by its insurer from using Woods Hole.

Asked if fishermen will be prevented from entering the lease area by their insurers due to radar risks, if Vineyard Wind would be willing to provide additional monies to fishermen as compensation, or negotiate with insurers like Lloyds to find a solution, Farmelant emailed, “[W]e do not anticipate such an outcome, and we will not speculate on possible solutions to purely hypothetical questions.”

In a statement to The Times, the Martha’s Vineyard Fishermen’s Preservation Trust expressed a wish for more research: “We are concerned about how the wind farms will affect all boaters’ ability to navigate in and around the wind-farm lease areas. Radar scatter, false reading, and image-mirroring may not only impact navigation, but also the ability for weather forecasters to accurately predict major weather systems within the wind-farm lease area. We feel further studies need to be performed to address these concerns.”

Source:  By Rich Saltzberg | The Martha's Vineyard Times | August 21, 2019 | www.mvtimes.com

This article is the work of the source indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

The copyright of this article resides with the author or publisher indicated. As part of its noncommercial effort to present the environmental, social, scientific, and economic issues of large-scale wind power development to a global audience seeking such information, National Wind Watch endeavors to observe “fair use” as provided for in section 107 of U.S. Copyright Law and similar “fair dealing” provisions of the copyright laws of other nations. Send requests to excerpt, general inquiries, and comments to query/wind-watch.org.

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