Berkeley Lab's awarded $2 million fibre optic project

In: Windfarms
Lawrence Berkeley National Laboratory (Berkeley Lab) has been commissioned to conduct a $2 million research project to implement fibre optic technology on the monitoring offshore wind turbines. The project will be executed in collaboration with UC Berkeley.

"A fibre cable has a glass core that allows you to send an optical signal down at the speed of light; when there is any vibration, strains, or stresses or changes in temperature of the material that is being monitored, that information will be carried in the light signal that is scattered back,” said Berkeley Lab scientist Yuxin Wu.

Off the California coast, the ocean floor drops off steeply, making floating wind turbines – which are tethered to the ocean floor by mooring chains, unlike conventional “fixed bottom” offshore wind turbines – the only viable option. But this technology faces several obstacles, including how to do maintenance and operations on remote installations in the ocean economically and how to monitor if hazards such as earthquakes or extreme weather conditions disrupt operations. Berkley Lab's project aims to tackle these obstacles with fibre optic cables.

“One of the most expensive components of a wind turbine is the gearbox; they also tend to be the part that’s most vulnerable to failure,” said Wu, who is also head of Berkeley Lab’s Geophysics Department. “Often before they fail they produce abnormal vibrations or excessive heat due to increased or irregular friction. We intend to use fiber optic cables to monitor the vibrational, strain, and temperature signal of the gearbox, in order to pinpoint where problems are happening.”

Wrapping fiber optic cables around the entire gearbox can provide a 3D map of changes with resolution at the millimeter scale. “It could help identify problems with the gearbox at an early stage, which would trigger emergency management, before a catastrophic failure causing loss of the whole turbine,” Wu said.

What’s more, Wu said the project intends to explore how the fibre optic cables can be used to detect marine mammal activity. The sensitivity of the fibre signal could allow for differentiation between, say, crashing waves and a pod of whales swimming by.

“Environmentally sustainable development of offshore wind is critical,” he said. “With a large offshore wind farm, there would be many of these mooring lines securing the turbine structures to the ocean floor. If a humpback whale swims by, what are the impacts of these mooring lines on their activities? Will the whales generate unique vibrational signals that can be picked up by the fiber optic sensors? If we can track the signals of a whale swimming by, it will allow us to evaluate whether and how the offshore wind turbine impacts marine mammals.”

Berkeley Lab added that it is looking to learn more about whales and other marine mammals from marine biologists and also seeking a partner to collaborate with to test the sensors in the ocean.

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