LZH-led group develops laser-based solution to biofouling of ship hulls

21 Feb 2023

German-funded project FoulLas is “green and efficient” at cleaning maritime surfaces by underwater laser.

The settlement of mussels and algae on ship hulls not only increases the fuel consumption of ships but can also threaten ecosystems. Laser Center Hannover (LZH) and partners have developed a new laser process to clean ship hulls.

Biofouling is the growth of algae, mussels, and other marine organisms on the hull of a ship. The fouling increases the flow resistance of the ship – and thus increases fuel consumption and CO₂ emissions. Mechanical cleaning of the fouling can damage the hull coating.

In addition, the fouling must be extracted if organisms or even parts of the ship's coating are not to get into the water. Scientists from the LZH, together with Laserline and the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research (IFAM), have developed an environmentally-friendly and efficient solution to the problem of biofouling.

Laser radiation can be used to lethally damage marine fouling underwater without damaging the underlying coating of a ship’s hull. The LZH scientists have developed a process in which the cells of the fouling are damaged by laser radiation in such a way that the fouling dies and is then washed away by the water.

The researchers conducted their investigations in the south harbor of the island of Heligoland, in the North Sea off Germany. There, they irradiated fouling samples with the laser, then returned them to the North Sea and checked them after two to four weeks.

“We were able to achieve a clear, time-delayed cleaning effect,” said underwater technology expert Dr.-Ing. Benjamin Emde from the LZH. “With simulated currents, as would be added in real life with a moving ship, the cleaning effect is further enhanced.”

Reducing emissions

Biofouling is not only a problem for reasons of fuel consumption as well as emissions. The fouling can lead to the introduction and spread of non-native species in foreign ecosystems.

“Species displacement is a major risk of biofouling,” said Emde. “If a ship introduces foreign organisms into an ecosystem through hull fouling, it can severely disrupt the ecosystem. In practice, this leads to ships being banned from docking in foreign ports, as has happened again recently with cruise ships, for example.”

Emde concluded, “Here, as well, cleaning with the laser is a good alternative to mechanical methods: because the introduced biomass is lethally damaged during laser cleaning, it is no longer dangerous for foreign ecosystems afterward.”

About the project

FoulLas (Fouling removal of maritime surfaces using laser radiation underwater) was carried out by Laserline GmbH, Fraunhofer IFAM and LZH. The project was funded by Germany's Federal Ministry for Economic Affairs and Climate Action (BMWK) under the funding code 03SX489 by the project coordinator Jülich.