Floating Offshore Wind Brings Challenges and Opportunities

Dennis Schroeder / NREL, licensed under CC-BY-NC-ND 2.0.

After a decade of dreaming, the prospect of commercial-scale floating offshore wind developments here in the United States is becoming a reality. Floating turbines will make renewable wind energy accessible to parts of the United States where it was previously thought to be off-limits. So far, offshore wind projects have predominantly used fixed-foundation turbines, which are driven directly into the seafloor and cannot be used in waters deeper than 60 meters. In contrast, floating offshore wind turbines can be installed in waters as deep as 1,000 meters, allowing for the expansion of offshore wind to new areas like California, Oregon, Washington, and the Gulf of Maine.

Floating offshore wind has immense potential to provide clean energy to millions of Americans, while helping the nation meet greenhouse gas emission reduction goals to prevent the worst impacts of climate change. Increasing our use of clean energy technologies, like offshore wind, is necessary to achieve President Biden’s goal of reducing greenhouse gas emissions by fifty percent by 2030.

However, like any energy infrastructure, floating offshore wind developments pose risks to the surrounding environment. Because we also face a biodiversity crisis, we must develop floating offshore wind responsibly, in a manner that protects local and regional biodiversity. Floating offshore wind platforms have their own unique benefits and risks compared to fixed platform turbines.

One such risk is wildlife entanglement. Floating turbines sit atop large platforms, which are secured to the seabed by mooring lines and anchors. Inter-array power cables connect the turbines to one another and may be buried or remain suspended in the water. Entanglement on floating wind’s mooring lines and cables themselves likely poses a low risk, because these lines and cables are large and relatively rigid. However, abandoned, lost, or discarded fishing gear and other marine debris could become ensnared in mooring lines and cables, where it may entangle whales, dolphins, turtles, fish, and diving seabirds (a process known as “secondary entanglement”). Secondary entanglement poses an additional threat to already stressed animals, like the critically endangered North Atlantic Right Whale. Entanglement in abandoned, lost or discarded fishing gear is a threat to many species of marine wildlife and often causes serious injury or death.

Floating offshore wind farms may also displace marine animals from crucial habitat areas. Some seabirds, fishes, and marine mammals may avoid floating offshore wind farms due to noise, vessel traffic, or other disruptions. The extensive underwater cabling of floating wind farms may also result in animals avoiding the area. If floating offshore wind turbines are placed in important habitat, this avoidance can have serious consequences. When displaced from feeding or foraging grounds by wind farms, animals must expend additional energy to find food elsewhere, which can compromise their survival. Additionally, avoidance by one species may impact other species in the area, because ocean food web relationships are complex. Mooring cables and anchors can also damage the habitat of benthic organisms that live in and on the seafloor.

Collisions with floating offshore wind turbines or maintenance and construction vessels can also prove fatal for seabirds, whales, and turtles. Vessel collisions are already a leading cause of mortality for marine mammals and sea turtles. Constructing and operating floating offshore wind turbines will increase vessel traffic, as vessels are needed to transport materials and personnel from shore to wind farm and back. With higher levels of vessel traffic comes an increased risk that vessels will hit whales, sea turtles, and other marine wildlife. Many floating turbines will be installed farther offshore—where winds blow at higher speeds—than fixed-foundation turbines. Birds show different flight behaviors in faster-blowing winds, which may increase turbine collision risk.

Given these risks, BOEM and state agencies must work proactively to reduce the environmental impacts of floating offshore wind. With the right policies in place, we can reduce ecological impacts through avoidance, research, monitoring, and comprehensive mitigation measures.

Even before issuing wind energy leases, policymakers can reduce risks to wildlife through project planning and siting. All siting and permitting decisions should be based on science and input from experts and stakeholders. Decisionmakers should avoid sensitive marine areas like National Marine Sanctuaries and state Marine Protected Areas. Likewise, floating turbines should be located outside of important wildlife habitat and migration routes, including NOAA-designated Biologically Important Areas (BIAs) for whales, Audubon Marine Important Bird Areas, designated critical habitat, Habitat Areas of Particular Concern, and areas with vulnerable benthic habitats such as corals and sponges. Similarly, turbine construction should be scheduled during seasons when sensitive species are less likely to be present.

Once potential floating offshore wind sites are identified, decisionmakers should conduct comprehensive ecological studies of these areas. Such studies provide more information on the appropriateness of a site and establish multi-year baseline ecological data for assessing the effects of an offshore wind project going forward. Sites should be studied and monitored before, during, and after all stages of project development, construction, and operation to continuously assess ecological impacts.

Agency officials should also require developers to take full advantage of emerging mitigation technologies, like tension monitors that wirelessly alert project operators to changes in line tension, indicating the presence of an entangled animal. Simple precautionary measures, like establishing a ten-knot speed limit for project vessels, can go a long way towards reducing the likelihood and severity of vessel strikes.

Through careful siting, responsible development, and extensive monitoring, floating offshore wind can achieve its promise of delivering carbon-free energy without undue harm to irreplaceable marine wildlife and habitat. Together, we can ensure that our clean energy future advances in harmony with the health of our valuable ocean wildlife and habitat.

This blog provides general information, not legal advice. If you need legal help, please consult a lawyer in your state.