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Germany may soon deploy drones and remote-controlled submarines for the assessment of offshore wind turbines

As offshore wind turbines perpetually withstand underwater stresses such as hurricanes, waves and salt water, a time to time assessment of the quality of the wind turbines is imperative. This assessment is conventionally done by sending down divers, which is not only unsafe for the divers but also economically exhausting for the companies.

Keeping in mind these challenges, Germany’s Federal Ministry for Economic Affairs and Energy is funding a research project for automatically evaluating information about the condition of installations.

Offshore wind farms can be located up to 100 kilometres from land. At these distances, they not only become covered in seaweed and shells, but are also particularly attacked by rust. In order to protect the outer layer of the towers, various different coatings are used both underneath the water and in the splash zone above the water’s surface. Although these extend the installations’ service life, they cannot prevent them from ageing completely.

Operators must regularly check the wind turbines to see what condition they are in. Up to now, this has been done by divers, but their work out at sea is time-consuming and costs a lot of money. In the future, however, checks on turbines are to be conducted by drones and mini-submarines called remote operated vehicles (ROVs).

Experts from companies and universities are joining together to research how ROVs can document the condition of wind turbines in order to save time and money. This includes the use of cameras and of other innovative technology. The aim is to enable the maintenance specialists to evaluate the data in real time on the mainland and to maintain or repair the installations as soon as this is needed.

As part of the Intelligent integrative systems for monitoring surface protection systems on offshore wind energy structures (IsyMoo) research project, sensors are being tested that are integrated into the coatings on the turbine towers. If the sensors recognise a change in material, for example, they forward this information to a drone or an ROV. These then transmit the sensor information to the control centre together with images taken by thermal imaging cameras and signals generated by ultrasonic systems.

As part of the research project, the photos and data obtained are to be automatically evaluated by technology such as machine-learning. This involves using a computer programme that continuously learns and grows in knowledge based on the information that is fed in, serving to speed up the rate at which visible damage is detected. In this way, the maintenance personnel receive ever more precise information about the condition of the wind installations.

This information can be used to consistently optimise maintenance cycles. As repair costs at sea are extremely high, this can serve as a vital step in reducing operating costs.

The Federal Ministry for Economic Affairs and Energy is providing €1.3 million in funding for the IsyMoo project up to the end of May 2021.