The California Energy Commission awarded two grants to researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) to develop fiber optics for monitoring offshore wind operations and underground storage of natural gas.
Yuxin Wu, a Berkeley Lab scientist and leader of both projects explains, “A fiber 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.”
Offshore wind development is prevalent in Europe and gaining popularity in the United States as well, but there are some challenges. For example, off the coast of California, the ocean floor has a sharp drop-off, which means that “fixed bottom” wind turbines are not an option. These turbines need to be anchored to the ocean floor, which isn’t possible with such a steep drop. That means that the only option is floating wind turbines which are connected to the ocean floor by mooring chains. Floating wind turbines aren’t without their problems either. They’re difficult to repair and maintain and hard to monitor for natural disasters like earthquakes or extreme weather.
According to Wu, “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. 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.""
By wrapping fiber optic cables around the gearbox of the turbine, scientists can get a three-dimensional image that shows them any problems or failures. Says Wu, “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 and his team are also trying to use fiber optic cables to monitor underground natural gas reservoirs. Gas is injected and withdrawn from the reservoir through steel boreholes, and the boreholes corrode over time, which can lead to gas leaks. By using electromagnetic time domain reflectometry (EM-TDR), the researchers can send electromagnetic waves into a conductive material and detect any changes that arise due to corrosion. That means we could have the ability to fix things before they break and cause massive damage.