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Silicone-based foul release paints save both environment and money

06 April 2022

Shipowners who use silicone-based foul release paints in the Baltic Sea save both the environment and money. This according to HullMASTER, a calculation tool developed in a research project within the Swedish Transport Administration's industry program Sustainable Shipping, which Lighthouse runs. The tool is now available for free.

In shipping, one is well aware of the importance of a clean hull. Algae growth alone can increase fuel consumption by at least 10 percent. Of course, this is neither economically nor environmentally sustainable. But how do you clean the hull in the most cost-effective and environmentally efficient way? It’s not so easy to answer,, says Erik Ytreberg, a researcher at Chalmers who led the two-year research project Hold.

"It is partly about direct costs - the price of antifouling paint, how often you need to dry dock and if you also need to perform underwater cleaning in between dockings, but then it is also about how much growth you get on the hull depending on which maintenance strategy you choose. The more growth, the higher fuel costs."

But it is not just shipping companies that pay a price. The marine environment, climate and people are affected by what is put on the hulls of ships. The most commonly used paints, chemically active paints, leak poison like copper and zinc straight into the marine environment. Today, however, there are non-toxic alternatives, such as silicone-based foul release paints which create a "smooth" surface that makes the growth drop at high speeds. The disadvantage of these is that they are more expensive to apply and require that the hull must be cleaned completely when repainting.

"Growth leads to increased emissions of greenhouse gases, nitrogen oxides that can lead to eutrophication, and particles that can affect human health. The challenge is to develop paints or hull cleaning techniques that are effective, but at the same time have a low environmental impact."

Calculating emissions from a given vessel is a complex issue. In addition to paint and maintenance strategy, the type of engine, fuel choice, possible exhaust reduction systems and, not least, the ship's route also play a major role. The intensity of hull growth varies geographically, while toxic emissions from antifouling paints are affected by salinity and temperature in the water. But now there is tool presented in the report that can handle this task: HullMASTER (Hull Maintenance Strategies for Emission Reduction). The idea is that both shipping companies and authorities will use the tool which is available free of charge on Chalmers' website.

"When we compare copper and silicone paints, we see that silicone paints not only provide environmental benefits - the cost is generally also lower over time for shipowners who use them. It’s a win-win situation", says Erik Ytreberg
He continues:
"The development has been very fast and the silicone paints have become much better than ten years ago. If you change from copper paint, the cost will be higher in the first years because you have to scrape off old paint and paint several coats of undercoat to get the silicone paint to adhere properly, but the service life will then be longer. In 8-10 years, you can count it all home. Our studies that have been going on for a year in different ports show that silicone paints are at least as effective as copper paints in preventing growth. This means that silicone paints are also an option for ships that spend long periods of time stationary."

HullMASTER is developed and validated for the Baltic Sea Region, but the idea is that it will be developed for a European or global area of ​​use.

"Together with DFDS, we will put out panels with different base colors in the ports they use to see how the growth develops over time."

The research report was written by Erik Ytreberg, Maria Lagerström, Dinis Reis Oliveira and Lena Granhag (Chalmers), Sofia Werner (SSPA) and Ann Larsson (University of Gothenburg).

Read the report


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