Trump admin halts 6 GW of offshore wind leases again

Two weeks after a federal judge struck down President Donald Trump’s executive order that blocked offshore wind development, the White House is once again pausing leases for five major offshore wind projects. This time, the administration cites concerns about radar interference and national security.

“Today’s action addresses emerging national security risks, including the rapid evolution of the relevant adversary technologies, and the vulnerabilities created by large-scale offshore wind projects with proximity near our east coast population centers,” Interior Secretary Doug Burgum said Monday in a statement.

The affected developments include Revolution Wind in Connecticut and Rhode Island, Coastal Virginia Offshore Wind, Vineyard Wind in Massachusetts, and Empire Wind and Sunrise Wind in New York. Combined, these projects represent nearly 6 gigawatts of planned generating capacity along the Eastern Seaboard, a region that has become a significant hub for data centre expansion.

The Department of the Interior said the decision was based on unclassified government reports — without specifying which agencies authored them or providing links — as well as “recently completed classified reports” from the Pentagon. According to the department, the pause will give the federal government time to work with stakeholders to address national security concerns.

The statement did not reference the extensive efforts already underway between the federal government and wind developers to mitigate radar-related national security risks, which have been ongoing for years.

The Department of Energy issued a report in February 2024 that appears to be referenced by the Interior Department. That report outlined multiple mitigation projects designed to address radar interference from wind turbines. Similar studies have been commissioned over the years, some dating back to the previous Trump administration.

“To date, no mitigation technology has been able to fully restore the technical performance of impacted radars,” the 2024 Energy Department report said. “However, the development and use of radar interference mitigation techniques, and collaboration both among federal agencies and between the federal government and the wind industry have enabled federal radar agencies to continue to perform their missions without significant impacts, and have also enabled significant wind energy deployments throughout the United States.”

Radar interference from wind turbines is a well-documented issue that has been studied for more than a decade, prompting researchers to develop a range of mitigation strategies.

Wind turbines pose unique challenges for radar operators due to their moving components. “The motion of a wind turbine gives it a complex Doppler signature,” said Nicholas O’Donoughue, a senior engineer at the Rand Corporation, in comments to TechCrunch.

Doppler effects refer to changes in the frequency of radar signals caused by moving objects. As turbine blades rotate, they alternately move toward and away from radar stations, causing signal distortions that depend on blade speed and angle.

Those factors, combined with other variables, can “challenge the detection of any targets that are near the wind farm,” O’Donoughue said.

Modern radar systems, however, can filter out wind farm interference. “The primary approach is to use adaptive processing algorithms, such as Space-Time Adaptive Processing, to learn the structure of a wind farm’s interference,” he said.

“Over time, the reflections from a wind farm can be processed to look for patterns, which can then be matched and suppressed. This process is analogous to how modern adaptive noise cancellation headphones work, albeit more complicated.” He added that objects with a low radar cross-section can still evade detection.

Because of these challenges, many wind projects are designed with radar considerations from the outset. “The most basic and widely employed mitigation method is wind farm siting, such as modifying the layout of a proposed wind farm to keep the wind turbines out of the line-of-sight of the radar,” the 2024 Energy Department report noted.