Scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) in California have been awarded a grant to study the use of fibre optics to monitor offshore windfarms
With the potential of floating windfarms in the state in mind, the California Energy Commission has awarded Berkeley Lab US$2M for the offshore wind project, which is being carried out in collaboration with UC Berkeley. Berkeley Lab will also collaborate with other organisations including PG&E, Schlumberger, and C-FER Technologies in Canada to carry out the offshore wind and other tests.
Berkeley Lab scientist Yuxin Wu explained, “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 Mr Wu, who is also head of Berkeley Lab’s Geophysics Department.
“Often before they fail, they produce abnormal vibration or excessive heat due to increased or irregular friction. We intend to use fibre optic cables to monitor the vibrational, strain, and temperature signal of the gearbox, to pinpoint where problems are happening.”
“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, stresses or changes in temperature of the material being monitored, that information will be carried in the light signal that is scattered back.”
Wrapping fibre optic cables around a gearbox can provide a 3D map of changes with resolution at the millimetre scale. “It could help identify problems with the gearbox at an early stage, which would trigger intervention before a catastrophic failure causing loss of the whole turbine,” Mr Wu said.
As he also explained, 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 waves and a pod of whales swimming by.
“Environmentally sustainable development of offshore wind is critical,” he said. “With a large offshore windfarm, there would be many mooring lines securing turbine structures to the seabed. 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 fibre optic sensors? If we can track the signals of a whale, it will allow us to evaluate whether and how the offshore wind turbine impacts marine mammals.”
The lab said the key to the project is optimising the technology and its sensitivity and developing real-time computing. “In addition to using commercial systems, our team is developing new fibre interrogators that will allow us to not only get to the original raw data but also play with the physics to better design a system that can give us the most sensitive signal we want,” Mr Wu said. “In addition, we will be developing machine learning-based edge computing methods to turn raw data into actionable intelligence quickly. This is key for real-time monitoring.”