Researchers at the Department of Energy's Pacific Northwest National Laboratory are using thermal imaging to help birds and bats near offshore wind farms.
PNNL is developing software called ThermalTracker to categorize birds and bats in thermal video. Birds and bats fly over offshore waters, but they can be difficult to track in such remote locations.
The software can help determine if there are many birds or bats near an offshore wind project and if they could be affected by the project. If that's the case, officials can consider adjusting the location of a proposed project or modifying an existing project's operations.
Biologists at the non-profit Biodiversity Research Institute are testing the system to determine how well it identifies birds compared to their field observations in Maine, one of the states considering offshore wind power.
Winds are stronger over the ocean than on land, and the Energy Department estimates the U.S. could potentially generate nearly twice the amount of electricity it currently uses if we captured the energy in winds that blow off our shores.
The nation's first commercial offshore wind project is off of Rhode Island and another proposed project near New York recently received early approval. Offshore wind is farther along in Europe, where nearly 3,600 offshore turbines have a total generation capacity of about 12,000 megawatts.
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 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.
Two previously published papers describe how an early version of ThermalTracker detected 81% of all animals recorded in thermal video and correctly classified 82% of those observed animals.
Matzner and her PNNL colleagues are improving their software. They've updated its algorithms so it can detect animals as video is being recorded, instead of processing video after the fact. Live data processing means the software only saves video when a bird or bat is detected. With less data to store, the system can be used for long-term observation and provide more complete information about birds and bats near offshore wind power sites.
The team is also creating a system that has "stereo vision," or 3D video by using two thermal cameras. 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.
Field researchers are testing the new stereo camera system this summer. While the two-camera system records, the Institute's scientists are documenting which birds they observe, how far away birds are, and how well the camera system works.
Next, Matzner and her colleagues will use the field biologists' notes to refine ThermalTracker algorithms so the software can better identify birds and bats from 3D video.