How does BOEM assess impacts to fisheries from offshore wind development?
BOEM analyzes proposed activities on the Outer Continental Shelf (OCS), including offshore wind, for potential impacts to marine species and habitats, multiple use conflicts, and access to OCS resources. Assessments include National Environmental Policy Act (NEPA) reviews at various stages of development and consultation with federal agencies and tribal governments.
These processes include public comment and coordination with stakeholders, industry, and regional fishery management councils. Not all activities warrant the same level of review or engagement.
BOEM scientists use the best-available science to inform their analyses, which is gathered from publicly available peer-reviewed publications and state and federal government reports.
BOEM also funds research to investigate the effects of offshore wind and other OCS exploration and development activities. For example, BOEM has funded studies investigating potential effects to marine species from electro-magnetic fields and underwater sound and impacts to commercial and recreational fisheries because of offshore wind development. Based on the information accumulated through research, BOEM scientists identify the types of activities that could affect various species and physical resources or impede other activities, evaluate the potential for impacts, and consider the range of mitigations that could be used to reduce or avoid potential impacts. This information is used to advise leadership and inform decision-making.
For a list of completed environmental studies related to offshore wind impacts to fisheries (including links to final reports), please see https://www.boem.gov/renewable-energy-research-completed-studies.
What are the effects of electromagnetic fields (EMFs) and heat from the energized cables?
EMFs are physical fields produced by electrically charged objects. Operation of turbines does not generate EMF; however, once the cable becomes energized it will produce a magnetic field. Cables will be buried beneath the seafloor and are wrapped in a sheath that eliminates direct electric fields and reduces magnetic and induced electric fields. The EMF decays quickly with distance from the cable and burial helps minimize potential exposure.
BOEM has completed several studies related to understanding the effects of EMFs on fish and invertebrates in other regions of the U.S. Current research suggests that, while some species (e.g., such as skates, sharks, and lobster) are sensitive to EMF, detrimental effects to populations are not expected. Some marine species are observed to respond to EMF, but the fields do not act as a barrier to movement.
Buried cable would generate sufficient heat to raise the temperature of the surrounding sediments by as much as 10 to 20°C above ambient temperatures within 1.3 to 2 ft of the cable. However, typical cable burial depths would limit potential exposure to substrate heating effects. These factors will be more fully considered in the NEPA analyses conducted for proposed activities when more detailed information is available.
What are the potential impacts of underwater noise from offshore wind development to fish and invertebrate species?
A wide range of sounds can be generated throughout the life of a wind energy development project, each with different relevant characteristics. Most of the sound sources used during high-resolution geophysical surveys are out of the hearing range of fish and invertebrates. In addition, many of these sources have very narrow beam widths and very short pulse durations, meaning it is highly unlikely that they would affect nearby fish or invertebrate fauna.
The sounds generated during percussive pile-driving, however, are high intensity and some of the acoustic energy overlaps with the hearing range of fishes and invertebrates (which is generally < 1 kHz). Once turbines are operational, low-level continuous noise is generated but this is very quiet, generally quieter than natural wind-generated ocean noise, and is unlikely to affect marine life.
BOEM takes into account sound and exposure-related effects during the NEPA process. For additional information, please refer to our BOEM Center for Marine Acoustics website.
Will areas in and around wind turbines and other structures exclude vessel traffic and fishing activity?
BOEM does not have the authority to restrict vessel traffic in and around offshore wind facilities, and the United States Coast Guard (USCG) has stated that safety zones and buffers would be evaluated on a case-by-case basis.
The USCG has also indicated that they intend only to implement restrictions during construction, but specific final determinations will be made at a later stage when more information is available. As an example, the USCG implemented a 500-yard safety zone around the wind turbine locations during Block Island Wind Farm construction activities.
Will electrical transmission cables be buried under the seafloor?
The standard commercial practice is to bury submarine cables 3-10 ft deep in waters shallower than 6,562 ft (2000 m). However, cable depths may vary by project and depending upon bottom type and other factors. For example, cables may be buried as deep as 32 ft under the seabed to mitigate local hazards, depending on water depth and bottom type. Other mitigation measures include adding protective covering, such as concrete mattresses (concrete block sections connected by metal braided cables).
How long is the typical lifespan of an offshore wind farm and will structures be removed after the expiration of a lease?
A typical offshore wind lease is valid for approximately 30 years. Before facilities may be installed under an approved Construction and Operations Plan (COP), a lessee must provide financial assurance that covers the decommissioning of all structures, cables, and obstructions.
Within two years of cancellation, expiration or other termination of the lease, the lessee would be required to remove all devices, works and structures from the site and restore the leased area to its original condition. Bottom-founded structures and related components are typically removed at least 15 ft below the mudline to avoid interference with future lessees and other activities in the area. Rights-of-way facilities (such as electrical transmission cables) may stay in place as long as they are being used and properly maintained, pending BOEM approval.
Does BOEM require information about fish and fish habitat prior to approving a construction and operations plan?
BOEM has information requirements for COPs in 30 CFR 585.626 that include a description of the results of biological surveys used to determine the presence of live bottoms, hard bottoms, and topographic features, and surveys of other marine resources such as fish populations (including migratory populations), marine mammals, sea turtles, and sea birds. Additionally, BOEM has developed a number of national and regional guidelines for renewable energy activities on the OCS to provide lessees, operators and developers with additional information or interpretation of these regulations. These include: Benthic Habitat Pre-Construction Survey Guidelines, Fisheries Pre-Construction Survey Guidelines, and Fisheries Communication Guidelines.