A professor at the University of Rhode Island has discovered that the Block Island offshore wind farm has altered several aspects of the nearby marine environment.
John King, an oceanography professor at URI’s Narragansett Bay Campus, has discovered that the wind farm has created a reef-like environment around the turbines.
The steel pilings that support the turbines have four separate legs which are connected by crossbeams. In total, there are five wind turbines, each with pilings and crossbeams. These structures have created an environment of different marine species, which created the artificial reef.
“If you look at the footprint out on the seafloor, it’s about a 30-meter-by-30-meter square,” King said. “The legs of the foundation are being colonized by all kinds of marine organisms.”
The majority of the organisms that were discovered on the wind farm’s foundation were blue mussels. Barnacles, algae and several other organisms were also discovered. The northernmost turbine was found to have the most mussels attached. At this site, King said the mussels are also starting to drop onto the seafloor. Additionally, the waste matter from the mussels has increased the organic carbon content on the seafloor around the turbine. The result of this, King said, is a relatively productive marine life community being created.
“This is a big change,” King said. “I view that as kind of an improvement. You have fish hanging around, you have other things like starfish. There’s a whole community out there that didn’t use to be out there, and it’s a decent quality community.”
King also helped discover that underwater cables used in the wind farm have not disturbed marine life. Underwater cables can leak varying amounts of electricity, which in turn creates an electrical field, generating magnetic fields.
Different species of marine animals use magnetic fields to follow migration routes or to detect prey. If the underwater cables leaked enough electricity to create an artificial electric and magnetic field, sea life may have been unable to properly follow migration routes or their detection of prey may have been disturbed.
However, King said the type of cable used in the Block Island wind farm has prevented this from occurring. The Block Island wind farm uses alternating current design cables, which have been found to be more effective than direct current design cables.
“They don’t generate very high magnetic fields, and the electric fields that they generate aren’t as high as direct current cables,” King said. “The design that they’re using for Block Island is superior to the direct current cables with respect for potential biological impacts. Magnetic fields and electric fields could potentially have an impact on marine organisms, but not at the levels we’re seeing associated with these power transmission cables.”
While the operation of the wind farm has not been found to negatively impact marine life, the construction of wind farms has the potential to harm certain species, according to King.
Some marine species, such as lobsters, live in ocean sediments as juveniles. The shock impact from pile driving, which is when the steel pilings for the turbine are hammered into the seafloor, may be strong enough to kill such species.
“There are certain life stages of species like lobsters and squid,” King said. “Hitting a hammer on top of a big piling could probably kill juvenile lobsters.”
In order to help scare away marine species before pile driving, several light “warning taps” with the hammer are performed before construction begins.
After examining the effects the wind farm has on the marine life near the turbines, King believes wind farms are important to develop.
“They are worthwhile because that is one of the ways we’re going to mitigate climate change,” King said. “Basically, we have to develop wind farms because we have to switch off to renewable energy.”
Block Island, which was previously powered by diesel generators, is now almost completely powered by wind turbines. A surplus of electricity on the island is also produced.