PNNL

Mama and calf humpback whales—considered a vulnerable species that might be entangled in underwater equipment—star in a new animation video that depicts the marine mammals’ scale and movements relative to floating offshore wind farms. The Bureau of Ocean Energy Management (BOEM) is using the animation to discuss development of the farms along the Pacific Coast with a wide variety of stakeholders.

Floating offshore wind farms are a relatively new concept. A few single platforms—as opposed to the multiple platform designs shown in the animation—with turbines are being deployed and tested in the U.S., Europe, and Asia, with Scotland deploying the first group of five floating turbines off its coast. And in the U.S., California, in particular, has established its commitment to increasing the state’s renewable energy portfolio, as several coal and nuclear power plants will be coming offline over the next 20 years.

The Deep End of the Ocean

Federal jurisdiction begins three miles off the coastline, which is where BOEM leases the seabed for energy development. The plan is to anchor offshore wind platforms into the seabed rather than driving piles into the bottom to support wind towers. The latter, which is typically done in shallower waters, is considered more disruptive to the surrounding environment and marine animals. The anchoring of floating wind platforms, on the other hand, is a drop and drag action, much like you’d anchor a boat. Except the anchors, which are the size of small ski boats are dragged into the seabed under tension.

Another advantage of the floating platforms and turbines is that they can be constructed in a port, then transported out to the site, avoiding costly and dangerous construction at sea. This, too, reduces disruption to the marine environment.

“It’s a tricky situation,” said PNNL’s Andrea Copping. “We want and need more renewable energy but we also have to be mindful of protecting the environment that’s providing us the resource. Our job was to help BOEM evaluate and demonstrate the risks floating offshore wind farms could pose to marine mammals.” Mooring lines, in particular, are of concern.

“Due to their size and migratory corridors along the Pacific Coast, it made sense to use humpback whales in the animation,” continued Copping. “It meant learning about their diving and swimming speeds, as well as their foraging habits, and understanding their body movements so that we could make the animation as realistic as possible.”

Size Matters

In order to create the animation, BOEM supplied PNNL researchers with estimated dimensions of the wind farm platforms, mooring lines, cables, buoys, and turbines, as well as the distances between the platforms and the water depth.

“What struck me most was the scaling in the animation,” said Molly Greer, a former post-doctoral researcher under Copping. “It helps people understand the size difference between the humpbacks and the offshore wind farms, and hopefully it puts some minds at ease about how these impressive marine mammals will navigate around them.”

Greer used a popular video editing software, Blender, to create the animation. The tedious task was ensuring the whales moved properly, which required Greer to study their movements and adjust their joints. In the end, she drew the whales freehand when she couldn’t find a first-rate digital recreation of them.

Copping says the duo hopes to write a paper on the interactions of whales and floating wind turbines, and do additional quantitative analyses for BOEM to continue to inform potential environmental risks from offshore wind.

Read the full report on the Tethys website.