Offshore wind turbines may have a dramatic impact on the performance of radar systems used by mariners, filling screens with clutter and potentially masking the presence of smaller fishing vessels that harvest the same waters currently under development, a new US government report has concluded.
The study, published by the Bureau of Ocean Energy Management (BOEM), the lead agency managing the sector in the US, flagged that the offshore wind sector’s ramp-up off an Atlantic seaboard already crowded with vessel traffic and competing ocean users could “pose [a range of] potential conflicts”.
“The installation of wind turbine generators towering several hundreds of meters above the sea surface with blade lengths exceeding 100 meters… poses potential conflicts with radar for air traffic control, weather forecasting, homeland security, national defence, maritime commerce, and other activities relying on this technology for surveillance, navigation, and situational awareness,” said the study authors.
Operational wind turbines can cause interference on radar screens which can “obfuscate” smaller watercraft or stationary objects, such as buoys, and lead to “ambiguous detections, generating a potentially confusing picture for the operator”, stated the report, which included input from both academia and industry.
The Biden administration has set bold “national goal” of having 30GW of offshore wind installed by 2030, bolstered by the recent New York Bight leasing round that added 7GW of potential capacity into the nation’s second busiest waterways to top out BOEM’s plans to approve 19GW of project permits by 2025.
These ambitions may be stymied by a number of factors, not least litigation by stakeholders including fisheries and environmentalists which claim that the industry will destroy livelihoods and marine ecologies and which cite the potential impact on marine radars as another reason to slow down installations.
The study argues that the rollout of offshore wind farms in configurations tailored to American waters and usage and deploying larger turbines as big as 15MW renders previous research into European and UK offshore wind farms obsolete, necessitating a new spate of research.
The impact on marine vessel radar (MVR) is of “particular concern” due to its being “a critical instrument for navigation, collision avoidance, and other specialized purposes such as small target detection and tracking, especially in low visibility conditions”.
The 800MW Vineyard Wind, owned by a consortium of Avangrid and Copenhagen Infrastructure Partners and located 15 miles (22km) south of Nantucket off of Massachusetts’ southern coast, is the first commercial-scale offshore wind farm to go into construction, ushering in a vast buildout of offshore wind with some 2,000 offshore wind turbines expected to be installed over the next decade.
The 132MW South Fork, the nation’s follow-up project, is located on the east end of Long Island, New York, while the 2.3GW Empire Wind owned by Norwegian oil major Equinor and British partner BP is sited just outside of the New York Harbour, the nation’s third busiest port.
The report notes that offshore wind turbines can impact search and rescue radars use as well, creating the potential for disaster along waterways notorious for inclement weather and fog.
MVR systems are required for all marine vessels by the International Maritime Organization (IMO), most of which use magnetron-based transmissions that are not designed to operate in complex environments “of a fully populated, continental shelf wind farm”. The study notes that there is no simple MVR modification to enable a “robust wind turbine generator operating mode”.
The report makes several recommendations to mitigate the impacts of this interference, including conducting more research, increased data collection, and better training for MVR operators to reveal more about the specific impacts and how they can be overcome.
Modifications to the wind turbines themselves could help reduce radar signature, the study added, but those modifications have not been fully proven and “are not available for the near term”.
Offshore wind opponents, particularly among the fisheries, have long been aware of the potential for radar interference and the issue is cited in the several lawsuits facing Vineyard Wind that aim to stop the project in its tracks.
Bonnie Brady, executive director for the Long Island Commercial Fishing Association, told Recharge: “The costs of fitting new radar systems may be cheap to a trans-Atlantic shipping company but to a family-owned small business such as a fishing boat it may be cost prohibitive.”
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