Future floating wind turbines off the coast of California will be anchored to deep trenches in the seabed by heavy-duty synthetic lines. Marine engineers have now figured out a way to turn the lines into oceanographic monitoring tools.
The technology is still in its pilot phase, but it is moving from a lab to real-world testing in Maine soon. It involves detecting even the slightest vibrations in the cables, and the data will give insight into ocean wildlife behavior and debris.
How does the tech turn the mooring lines into an underwater tracker?
How energy infrastructure is turned into ecosystem monitoring equipment
The floating wind energy sector is expanding into deeper waters, and the cables required to attach the platforms to the sea floor can reach hundreds of feet long.
The aim is to generate clean energy, but it should not come at the cost of the environment. Regulations demand that ecosystem monitoring is carried out around the turbine sites, but the traditional tools have shortcomings. Underwater acoustic sensors like hydrophones attached to buoys or survey vessels rely on batteries that need frequent replacing. The equipment is vulnerable in the open ocean or exposed on the surface, and maintenance is costly.
Routine maintenance is complicated by the increased structural drag of mounting sensor units onto the moorings.
There are also ghost nets to contend with, which are discarded fishing gear that drifts through the ocean and gets tangled around the subsea equipment. Marine animals are also at risk of getting caught in the debris.
Engineers needed to work out an approach whereby acoustic signals and physical impacts could be monitored across long distances without additional hardware. The system also needs to be electrically simple and not add high operational costs.
Engineering and acoustic obstacles revealed during scaled testing
There are technical hurdles involved in testing monitoring equipment in real-life ocean conditions. Computer modelshave limited use in these cases because the conditions cannot be replicated.
In deep offshore waters, wave action, currents, and commercial shipping activity create a high level of background noise. To distinguish between low mammal vocalizations or ambient noise, the measuring equipment needs to be highly sensitive along the full length of the mooring line, according to the California Environmental Quality Act.
The tethers are also under constant mechanical tension at the same time as being exposed to salt and undergoing flexing. During the first trials, the attachments became detached in rough seas, or they interfered with management of rope loads.
Long-term reliability had to be evaluated, so the researchers had to move operations to specialized offshore sites in Maine. Engineering teams had to test the sensors in cold water with high tidal surge for future deepwater deployment along America’s coastlines.
Optical fibers embedded in mooring ropes convert synthetic lines into acoustic sensors
The system works by embedding continuous optical fiber strands directly inside the synthetic core of the mooring line during manufacturing.
Engineers use Distributed Acoustic Sensing, sending rapid laser pulses down the integrated fiber, according to the California Energy Commission. As acoustic vibrations from whale calls or physical drag from snagged ghost nets strike the tether, they cause microscopic strain and phase changes in the backscattered laser light.
Specialized algorithms analyze these optical shifts in real time, effectively converting the entire mile-long cable into a continuous acoustic sensor. This approach eliminates external electronics along the tether while providing full-length monitoring.
Focusing on establishing baselines for detections
However, researchers emphasize that current field trials in Maine remain focused on establishing baseline detection thresholds. While the technology demonstrates high sensitivity in controlled settings, scientists must still determine how effectively algorithms isolate faint biological calls from operational noise generated by turbine gearboxes and hull movements.
If field testing confirms optical fiber durability against synthetic rope fatigue, the system could provide real-time marine mammal tracking without adding standalone oceanic hardware. Resolving these acoustic filtering challenges in Atlantic test waters represents the necessary next step before integrating continuous fiber sensing into commercial floating offshore wind installations.
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