Cleaning up marine fouling from ships is a big deal for ship operators. Biological pollutants adhering to the hull increase the resistance to flow and, therefore, fuel consumption and polluting gas emissions throughout the ship. For example, the deposition of mussels and algae on ship hulls not only increases the fuel consumption of ships, but also threatens the ecosystem.
Now, the Laser Center Hannover (LZH) and its partners have developed a laser process for cleaning ship hulls.
Biofouling is caused by the growth of algae, mussels and other marine organisms on the hull of a ship. Fouling increases fuel consumption and CO2 emissions by increasing the vessel's resistance to flow. In this regard, if they are treated by traditional mechanical cleaning methods, the hull coating will be damaged. Also, the dirt has to be extracted if you don't want organisms or even parts of the hull coating to get into the water.
Eco-Friendly Laser Underwater Cleaning
Laser radiation can be used to destroy marine fouling underwater without damaging the underlying coating of the hull. Scientists at the LZH have developed a procedure that kills the dirt by destroying the cells of the dirt with laser radiation so that it is washed away with water after a certain period of time.
The researchers conducted their investigation in the southern port of Helgoland. There, they irradiated dirt samples with laser light, then sent them back to the North Sea, where they were inspected two to four weeks later. Dr Benjamin Emde, an expert in underwater technology from LZH, said: "We were able to achieve a noticeable, time-delayed cleaning effect. The cleaning effect was further enhanced by simulating ocean currents, as would be joined by a moving ship in real life."
Reduce emissions and avoid species displacement
Not only does biofouling increase fuel consumption and carbon emissions, fouling can also lead to the introduction and spread of non-native species in foreign ecosystems. "Species displacement is the main risk of biofouling," Emde said. If a ship introduces alien organisms into an ecosystem through hull fouling, it can severely damage the ecosystem. So this in reality has resulted in ships being banned from calling at foreign ports. Therefore, laser cleaning can be a good substitute for mechanical cleaning. The organisms brought in by the ship during the laser cleaning process are fatally destroyed and no longer pose a danger to the foreign ecosystem.
The project FoulLas (underwater use of laser radiation to remove dirt from sea surfaces) was carried out by Laserline GmbH, Fraunhofer IFAM and LZH.
