Cleaning marine fouling from ships can be a major event for ship operators. Biological contaminants attached to the ship's hull increase resistance to flow and can consequently increase fuel consumption and pollutant gas emissions throughout the ship. For example, deposits of mussels and algae on the hull not only increase the fuel consumption of the ship but also threaten the ecosystem.
Today, the Laser Center Hannover (LZH) and its partners have developed a laser process to clean the hulls of ships.
Biological pollution is formed by the growth of algae, mussels and other marine organisms on the hull of a ship. The fouling increases fuel consumption and CO2 emissions by increasing the flow resistance of the ship. In response, they can damage the hull coating if they are treated by traditional mechanical cleaning methods. In addition, the fouling must be extracted if the organisms or even parts of the hull coating are not wanted to enter the water.
Eco-friendly laser underwater cleaning
Laser radiation can be used to destroy marine fouling underwater without damaging the underlying coating of the ship's hull. scientists at LZH have developed a procedure to destroy the cells of the fouling by laser radiation, causing the fouling to die and thus be washed away by the water after a period of time.
The researchers conducted their investigation in the southern harbour of Helgoland Island. There, they irradiated fouling samples with a laser and then sent them back to the North Sea, where they were examined two to four weeks later. "We were able to achieve a clear, time-delayed cleaning effect," says underwater technology expert Dr.-Ing. Benjamin Emde from the LZH. "
Reducing Emissions and Avoiding Species Displacement
Biological contamination not only increases fuel consumption and carbon emissions, fouling can also lead to the introduction and spread of non-native species in foreign ecosystems. "Species displacement is a major risk of biofouling," Emde says. If a ship introduces foreign organisms into the ecosystem through hull fouling, it can seriously damage the ecosystem. So this has, in reality, led to ships being banned from calling at foreign ports. Therefore, cleaning with a laser can be a good alternative to mechanical cleaning methods. By fatally destroying the organisms brought in by the ship during laser cleaning, there is no further danger to the foreign ecosystem.
The project FoulLas (Removal of surface fouling underwater using laser radiation) was carried out by Laserline GmbH, Fraunhofer IFAM and LZH.
