Environmental Assessment of Offshore Wind Power Generation Near Rhode Island: Acoustic and Electromagnetic Effects on Marine Animals
James H. Miller - miller@uri.edu
Gopu R. Potty, Kathleen Vigness Raposa, David Casagrande, Lisa Miller, Steven E. Crocker, Robert Tyce, Jonathan Preston, Brian Roderick
Dept. of Ocean Eng.
Univ. of Rhode Island
Narragansett, RI 02882
Jeffrey A. Nystuen
Univ. of Washington
Seattle, WA 98105-6698
Peter M. Scheifele
Univ. of Cincinnati
Cincinnati, OH 45267
Popular version of paper 4aAB12
Presented Thursday morning, October 29, 2009
158th ASA Meeting, San Antonio, TX
Offshore wind turbines have the potential to meet a significant portion of the electricity demand in the United States. Several states are in the planning process for large wind turbine farms off the East Coast including Rhode Island. As part of this planning process, ocean engineers and scientists from the University of Rhode Island, the University of Washington and the University of Cincinnati have been tasked with predicting the impacts of the wind turbines on marine life.
Two types of impacts are acoustic and electromagnetic. European investigators have found that vibration from the wind turbine can radiate through a monopile (single tower) structure into the ocean as noise. The Rhode Island wind farm turbines will be mounted on metal lattice structures. This study compares the radiated noise from the turbines to other man-made and natural sources of sound such as shipping, waves, and marine mammals.
One way of comparing the effects of different sources is an average noise intensity budget. A noise budget has been computed for the waters off Rhode Island, and the investigators have shown that the existing noise from shipping and waves are both greater than that from the proposed wind farm. The shipping noise is dominated by commercial vessels, fishing vessels, and ferries. Using this noise budget, the investigators predict that the effects on marine life from the wind turbine noise will be minimal as long as the wind turbine structures are designed properly.
The electric power transmission lines connecting the wind turbines to shore have electric and magnetic fields that surround the underwater cables. These fields have the potential to disrupt the navigation of some marine animals including lobsters and sharks. The authors are studying the magnitude and effects of these fields. They are measuring the fields around existing underwater power transmission lines in the region and the effects of those power lines. The assessment of the electric and magnetic field effects is ongoing and should be finished by the middle of 2010.