Sound from wind farm operations having no effect on environment

But pile driving during construction could have affected marine life

Todd McLeish

After periodic acoustic monitoring of the Block Island Wind Farm since before it began operation in 2016, a University of Rhode Island ocean engineer has found that the sound from the operation of the turbines is having no detectable effect on the marine environment.

“The sound from the wind turbines is just barely detectable underwater,” said James H. Miller, URI professor of ocean engineering and an expert on sound propagation in the ocean. “You have to be very close to hear it. As far as we can see, it’s having no effect on the environment, and much less than shipping noise.”

Miller and a team of specialists from Woods Hole Oceanographic Institution, Marine Acoustics Inc., and others monitored the noise from the operation of the wind farm using hydrophones in the water and geophones—which measure the vibration of the sea bed—on the seafloor.

“We listened to a lot of ships, a lot of whales, wind and fish, but the sound of the turbines was very, very subtle,” he said. “We were 50 meters away from the turbine and we could just barely hear some noise at a very low level. And above the water line we just barely heard the swishing of the blades turning.”

During the two-week pile-driving stage of construction, however, Miller said the sound was quite loud. Pile driving is the first step in building the support structure for the turbines.

“The wind farm developers know pile driving is loud, so they start with some soft tapping to alert marine life that might be sensitive to the sound,” he said. “Once they realize it’s coming, marine life can move away.”

The greatest concern from the pile driving is its effects on the critically endangered North Atlantic right whales. To minimize the impacts, pile driving was prohibited between Nov. 1 and May 1, when the whales were most likely to be in the area. 

Trained observers were also hired by the developers to watch for any whales that may have wandered into the construction zone. And pile driving was restricted to the daytime to facilitate visual detection of whales nearby.

The most surprising result of the acoustic monitoring of the wind farm construction was the intensity of the vibrations felt in the seabed from the pile driving.

“The impact on the animals on the seabed is potentially worse than for those in the water column,” Miller said. “It may have had an effect on nearby bottom-dwelling organisms like flounder and lobsters, which have a huge economic value in the state. But we’re still trying to understand what that effect may be.

“Fish probably can’t hear the noise from the turbine operations, but there’s no doubt that they could hear the pile driving,” he added. “And the levels are high enough that we’re concerned.”

Miller’s acoustic monitoring of the wind farm is part of an effort by the federal Bureau of Ocean Energy Management to understand the impact of wind turbine construction and operations on the environment so future wind farms can be planned appropriately.

The Bureau has funded Miller — through Nebraska-based engineering consultants HDR Inc. — to evaluate the sound from wind farm construction and operations at other locations along the East Coast. He will soon deploy his acoustic instruments in the waters off Maryland and Virginia as preparations begin for the first offshore wind turbines off the Mid-Atlantic coast.

“The conditions are different there — the seabed is different, the oceanographic conditions are different, it’s warmer there longer — all of which can have an impact on sound propagation,” Miller said. 

“The seabed there is much more homogenous sand than we have up here, which we think might make the sound levels a little bit louder. It’s something we’re still trying to understand.”

About 1,000 offshore wind turbines have been proposed for installation in the waters from Massachusetts to Georgia in the coming years.

Miller is also part of an HDR team monitoring sound from shipping, oil exploration and production, and other sources in the Gulf of Mexico as part of a separate Bureau of Ocean Energy Management-funded project to describe what he calls “the existing noise soundscape” in the Gulf.

“It’s really exciting that we’re being asked to do so much of the acoustic monitoring in the oceans around the U.S.,” Miller concluded. “We’ve become the national experts, which has added to Rhode Island’s reputation as the Ocean State.”

URI’s Narragansett Bay Campus is home to the URI Graduate School of Oceanography (GSO), one of the world’s premier oceanographic institutions. Founded in 1961, GSO has built a reputation for excellence in deep water oceanographic research, coastal planning and management, sustainable fisheries and monitoring the health of Narragansett Bay. With operations, researchers, faculty and students worldwide, the Bay Campus education and outreach programs train the next generation of scientists and policymakers, while ensuring Rhode Island’s K-12 teachers and students gain an appreciation for the importance of ocean science through a variety of hands-on programs.

On Nov. 6, Rhode Islanders will vote on Question 2, a $70 million higher education general obligation bond that includes $45 million for upgrades to the Narragansett Bay Campus. If approved, proceeds from the bond will be used to improve the GSO’s pier (required to accommodate a newly awarded Regional Class Research Vessel from the National Science Foundation valued at more than $100 million), construct a 20,000-square-foot Ocean Technology building, a Marine Operations building and fund other necessary improvements to campus facilities.