Reducing ship hulls drag is one of the key issues that make ships more environmentally friendly and reduces their ecological footprint. Moreover, preventing fouling without using coatings that release toxic substances into the water, threatening the maritime ecosystem is another important task in the shipping sector. Coating a ship with a permanent layer of air underwater will address both problems: Moving within a hull of air will reduce drag, while the air layer helps in preventing fouling as it works as a separating barrier between maritime life and the ship hull, preventing direct contact. The European Union project AIRCOAT (Air Induced friction Reducing ship Coating) targets at exactly that. The coating that reduces ships’ frictional resistance is based on a self-adhesive foil technology that forms a passive air layer by utilising the biomimetic Salvinia effect. This reduces energy use and ship emissions and therefore creates both economic and environmental benefits. AIRCOAT is a refit technology with a strong potential to make the shipping industry more sustainable. Being an environmental-friendly refit technology, AIRCOAT will enhance both the strategic and the revenue value for end-users (ship owners, shipyards, etc.) and create new business opportunities. AIRCOAT is a passive air lubrication technology, which targets to outperform the skin friction reduction potential of active air lubrication. Active air lubrication systems are already available on the market, and initial results indicate significant long-term energy savings of 4 %. The significant advantage of passive air lubrication (i.e. keeping a permanent layer of air underwater) - as compared to active air lubrication (continuous production of air bubbles with huge compressors) is obvious: In the case of active (air bubble- induced) air lubrication, the ship remains wet, and the air does not touch the ship. In our passive air lubrication case, the ship remains dry: the water does not touch the ship, thus also providing environment-friendly protection against corrosion and fouling. Here, a cost-benefit assessment is performed both for ocean-going ships and container vessels (deep-draught case) and for boats and small vessels (shallow-draught case) to assess the potential for savings due to reduced fuel consumption as a consequence of air coating. Finally, our quantitative analysis is accompanied by a risk assessment. We conclude that even the shallow-draught case in inland shipping opens a considerable potential for fuel saving and CO2 emission reduction. A significantly larger contribution, however, can be expected from the application on the global fleet of large maritime vessels.
Biomimetic self-adhesives foils instead of paints. A business case for a sustainable ship hull coating
2021
2021
2 pages
Conference paper
Electronic Resource
Unknown
Biomimetic friction reducing hull surfaces could reduce ship emissions
Fraunhofer Publica | 2017
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