Fall 2021

Electric and Magnetic Field (EMF) Considerations for Offshore Wind Projects

By Chris Long, Sc.D., DABT, and Jiayang Chien, M.P.H.

Offshore wind projects commonly include electric and magnetic field (EMF) assessments to evaluate potential human health and ecological effects, along with mitigation strategies, in the permitting and design processes. 

What is the first image that comes to mind for an offshore wind project?  Undoubtedly, it is of a mammoth wind turbine rising out of the ocean, with blades the length of a football field.  However, offshore wind projects have a number of other components, including miles of submarine cables buried beneath the ocean floor for transmitting the electric power to shore.  On shore, typical project components can include underground duct banks with high-voltage transmission cables buried within city streets, additional overhead transmission lines within utility rights-of-way, and new electrical substations.  EMFs are associated with each piece of offshore and onshore electrical infrastructure, and as a result, EMF assessments are commonly conducted as part of the permitting process for offshore wind projects to evaluate potential human health and ecological effects from EMF exposure.

EMFs are invisible lines of force associated with anything that generates, transmits, or uses electricity, including not only high-voltage transmission lines and substations, but also the overhead and underground distribution lines on residential streets, home wiring, and household appliances.  As illustrated by the figure, power frequency (60-Hertz) alternating current (AC) EMFs are an extremely low frequency form of non-ionizing electromagnetic radiation.  Unlike ionizing radiation (e.g., ultraviolet [UV] rays, X-rays, gamma rays), power frequency EMFs do not carry enough energy to break molecular bonds and damage DNA, biological cells, or tissues.

It is the consensus of a number of public health agencies and expert scientific committees… that there are no confirmed human health risks for power frequency EMFs.”

However, exposure to power frequency EMFs emerged as a public health concern in the late 1970s when the Wertheimer and Leeper (1979) epidemiological study reported statistical associations suggesting that children residing in greater proximity to overhead power lines may have a small increased risk of childhood leukemia.  Although uncertain and limited, this and other early epidemiological studies triggered a massive international research effort, which included numerous mechanistic, laboratory animal, and epidemiological studies, designed to understand whether and how power frequency EMFs could cause childhood leukemia and other diseases (see Moulder, 2000).  Despite about 40 years of scientific research and thousands of published studies, scientists have found no plausible biological mechanism whereby biology can be adversely affected by typical levels of 60-Hertz (or steady) EMFs, and lifetime exposures of laboratory animals to these EMFs have likewise shown no carcinogenic potential.  It is the consensus of a number of public health agencies and expert scientific committees, including the World Health Organization (WHO), the US Environmental Protection Agency (US EPA), and the National Institute of Environmental Health Sciences (NIEHS), that there are no confirmed human health risks for power frequency EMFs.

Nonetheless, EMF exposures remain a source of public concern, and EMF assessments are now a well-established component of the permitting process for new transmission lines and line-upgrade projects in many states.  This has carried forward to offshore wind projects, where the same tools can be used to conduct EMF assessments of submarine cables.  For offshore wind projects, EMF assessments address not only potential human exposure to EMFs, but also EMF exposures of marine species, including bottom-dwelling species such as lobsters and skates that reside in the sediments above buried submarine cables.  

Electromagnetic Spectrum

Horizontal Infographic of the Electromagnetic Spectrum from Non-Ionizing Radiation to Ionizing Radiation

Click to Enlarge Figure.

It is well established that there are a number of “magnetosensitive” marine species, including lobsters, salmon, American eel, sturgeon, yellowfin tuna, sharks, skates, rays, and sea turtles, that use the earth’s geomagnetic field for specific purposes such as orientation, navigation, prey location, and long-distance migration.  In addition, “electrosensitive” marine species, including sharks, rays, skates, and sturgeon, utilize electrosensory capabilities for navigation and prey detection.  As compared to human health, there is not as extensive a body of research to inform the assessment of how submarine cable EMFs might impact marine species, and this is an active area of research.  The available research suggests that both magnetosensitivity and electrosensitivity in marine species have developed so as to be specifically attuned to natural EMF sources such as the earth’s magnetic field and marine species bioelectric fields (e.g., heartbeats), and there is a lack of evidence of sensitivity to the 60-Hertz AC EMFs associated with submarine cables.  Importantly, current research shows that EMF exposures associated with submarine export cables will be highly localized and transient, and they are reversible once an organism moves away from the cable location (i.e., there is no “accumulation” of short-term peak EMF exposures).

As greater numbers of offshore wind projects are approved and constructed off the US coast, the encounter rate of marine species with EMFs from buried submarine cables and other offshore electrical infrastructure will continue to increase.  There is thus a need for continued scrutiny of EMFs from these projects.  In addition to continued research focused on marine species interaction with 60-Hertz AC EMFs, additional research is also needed for direct current (DC) EMFs given the likelihood that offshore DC submarine cables will gain increased usage in future projects due to their greater capacity and efficacy for long-distance power transmission.  In closing, it bears mentioning that mitigation of EMF impacts is specifically considered in the design of offshore wind projects.  For example, both seafloor burial and cable design can serve to reduce EMF impacts at and above the seafloor.

Contact Info

The authors can be reached at clong@gradientcorp.com and jchien@gradientcorp.com.


Moulder, JE. 2000. “The Electric and Magnetic Fields Research and Public Information Dissemination (EMF-RAPID) Program.” Radiat. Res. 153(5 Pt. 2):613-616. doi: 10.1667/0033-7587(2000)153[0613:teamfr]2.0.co;2. 

Wertheimer, N; Leeper, E. 1979. “Electrical wiring configurations and childhood cancer.” Am. J. Epidemiol. 109(3):273-284. doi: 10.1093/oxfordjournals.aje.a112681.