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The Underwater Sound from Offshore Wind Farms
Jennifer Amaral, Kathleen Vigness-Raposa, James H. Miller, Gopu R. Potty, Arthur Newhall, and Ying-Tsong Lin
Efforts to reduce carbon emissions from the burning of fossil fuels have led to an increased interest in renewable energy sources from around the globe. Offshore wind is a viable option to provide energy to coastal communities and has many advantages over onshore wind energy pro- duction due to the limited space constraints and greater resource potential found offshore. The first offshore wind farm was installed off the coast of Denmark in 1991, and since then numerous others have been installed world- wide. At the end of 2017, there were 18,814 megawatts (MW) of installed offshore wind capacity worldwide, with nearly 84% of all installations located in European waters and the remaining 16% located offshore of China, followed by Vietnam, Japan, South Korea, the United States, and Taiwan. This equated to 4,149 grid-connected offshore wind turbines in Europe alone, with the number increasing annually since then (Global Wind Energy Council, 2017). In the last 10 years, the average size of European offshore wind farms has increased from 79.6 MW in 2007 to 561 MW in 2018 (Wind Europe, 2018).
On land, China leads the onshore wind energy market with 206 gigawatts (GW) of installed capacity, followed by the United States with 96 GW in 2018 (Global Wind Energy Council, 2019). Over 80% of the US electricity demand is from coastal states, but onshore wind energy generation is usually located far from these coastal areas, which results in long-distance energy transmission. With over 2,000 GW of offshore wind energy potential in US waters, which equals nearly double the electricity demand of the nation, offshore development could provide an alter- native to long-distance transmission or development of onshore installations in land-constrained coastal regions (US Department of Energy, 2016). With the potential for offshore wind to be a clean and affordable renewable energy source, US federal and state government interest
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in development is continuing to grow. The US Bureau of Ocean Energy Management (BOEM) is responsible for overseeing all the offshore renewable energy develop- ment on the outer continental shelf of the United States, which includes issuing leases and providing approval for all potential wind energy projects.
The Block Island Wind Farm (BIWF) was completed in 2016 off the East Coast of the United States in Rhode Island and is the first and only operational wind farm in US waters to date. It produces 30 MW from five 6-MW turbines and is capable of powering about 17,000 homes. As of August 2019, there were 15 additional active offshore wind leases that account for over 21 GW of potential capacity off the East Coast of the United States.
Offshore wind farms are generally constructed in shal- low coastal waters, which often have a high biological productivity that attracts diverse marine life. The aver- age water depth of wind farms under construction in 2018 in European waters was 27.1 meters and the aver- age distance to shore was 33 kilometers (Wind Europe, 2018). As a by-product of the construction, operation, and eventual decommissioning of offshore wind farms, sound is generated both in air and underwater through various activities and mechanisms. With the rate of wind farm development continuing to increase world- wide, regulatory agencies, industry, and scientists are attentive to the potential physiological and behavioral effects these sounds might have on marine life living in the surrounding environment. The contribution of sound produced during any anthropogenic activity can change the underwater soundscape and alter the habitats of marine mammals, fishes, and invertebrates by poten- tially masking communications for species that rely on sound for mating, navigating, and foraging. This article discusses the typical sounds produced during the life of
Volume 16, issue 2 | Summer 2020 • Acoustics Today 13

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