Offshore Wind: Watching Birds and Bats
A new software system has been developed that automatically categorizes birds and bats from thermal imaging video to help protect these animals from offshore wind turbines.
Night vision goggles use thermal imaging, which captures infrared light that's invisible to the human eye, and researchers at the Department of Energy's Pacific Northwest National Laboratory (PNNL) are using this technology in the new application, called ThermalTracker.
The software can help determine if there are many birds or bats near an offshore wind project area and if they could be affected by the project. If that's the case, officials can consider adjusting the location or modifying an existing project's operations.
Biologists at the non-profit Biodiversity Research Institute are testing the system this summer to determine how well it identifies birds compared to their field observations in Maine, one of the states considering offshore wind power.
American officials are aiming to make U.S. offshore wind environmentally responsible, including limiting its impact on birds and bats near American shores. Today, most wind power sites are evaluated for birds and bats by biologists who stand in a field and take notes on what they see. For offshore wind power sites, scientists board a boat, but can only observe in daylight and when the weather cooperates. Remote sensing technologies could enable longer-term bird and bat monitoring that is also less expensive and labor-intensive.
Scientists have long used thermal imaging to observe bats, which are nocturnal and can't be seen with traditional video at night. But while thermal cameras see general animal shapes when visibility is low, they don't provide clear images or color, which makes identifying animals difficult.
PNNL's solution involves algorithms that can identify birds and bats based on their flight behaviors. The ThermalTracker software specifically evaluates two characteristics: the shape of the path that birds or bats take to fly from point A to B and how frequently their wings beat up and down. The software evaluates thermal video for these behaviors and then determines whether the observed animals are bats or belong to bird families such as gulls, terns or swallows.
The team is also creating a system that has "stereo vision," or 3D video by using two thermal cameras instead of the just one. Having 3D video provides depth perception which helps determine if birds are flying at the heights where turbines spin and if birds are avoiding existing turbines. Stereo vision will also reveal how far a bird is from a camera, which can determine bird size and, in turn, more accurately identify a bird.
Offshore wind power is starting to take off in the U.S. The nation's first commercial offshore wind project is operational off of Rhode Island and another proposed project near New York recently received early approval. Offshore wind is further along in Europe, where nearly 3,600 offshore turbines have a total generation capacity of about 12,000 megawatts.