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Wednesday, January 5, 2022 

According to Hoegh Autoliners, a thin coat of paint on the hull of its vessels is reducing CO2 emissions by around 4%, by limiting the growth of barnacles, algae and other marine organisms.

The company says that if these organisms build-up on a vessel’s hull, causing fouling, the impact can be huge. In the old days of wind and sail, fouling could be so bad a ship could hardly move. Thanks to modern propulsion systems, fouling no longer causes vessel immobility, but it does lead to increased emissions.

Even with a perfectly clean hull, a vessel such as one of Hoegh's ro-ros, uses several tonnes of fuel a day, resulting in release of CO2 into the atmosphere. If fouling builds up on the vessel’s hull, it impacts on the vessel’s hydrodynamics. This means more fuel is required to move the ship through the water, pushing up CO2 emissions. In a study by Marintek, it was estimated that fouling increases fuel consumption and emissions on an average vessel by around 15% over a 60-month period. On a very large vessel, this causes several thousand extra tonnes of CO2 to be released into the atmosphere each year.

Modern hull paints are designed to stop fouling from building up on the vessel’s hull. The best is extremely effective, essentially keeping the hull entirely fouling free for 60 months or more, working in one of three ways:

  • Biocide release paints contains tiny amounts of biocide. This is slowly released as the paint degrades, dissuading marine organisms from attaching to the hull.
  • Silicone paints give the hull a very smooth surface that fouling can’t hold onto.
  • Silicon-hydrogel paints combine silicon with a special hydrogel surface that appears like water, essentially rendering it invisible to fouling organisms.

Whatever the mechanism, Hoegh says that the outcome is essentially the same: the vessel’s hull remains smooth, which means less fuel is needed for it to sail.

Höegh Autoliners says it is committed to reducing emissions from its operations. Hull paints are estimated to reduce fuel use by an average of 4% per vessel across the fleet. During a year of operation, this reduces CO2 emissions by around 50,000 tonnes.

The company adds that many other factors affect fuel consumption and emissions, and it is embracing many of these improvements.

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