Green & Efficient Photo: DNV GL Antifouling – old problem, new solutions? Marine growth can affect ship performance drastically, typically resulting in 30–50 % higher fuel consumption (and associated emissions) compared to a smooth hull. Antifouling is thus both an economic and ecological necessity The standard antifouling solution uses biocidal paints. In contact with seawater, such paints release biocides which form a toxic boundary layer, preventing marine growth. As the ship moves through water, the toxins are washed off and the paint must re-supply the protective biocide layer. As the hosting paint also dissolves in water, the surface of such »self-polishing copolymers« (SPCs) remains more or less smooth. Typically after five years, the paint and its embedded biocides have been used up and the ship is re-coated in drydock. Since the 2008 ban on tributyltin (TBT), copper compounds have filled the gap, mixed with various herbicides and fungicides, dubbed »boosters«. The boosters in particular have come under scrutiny, resulting in regional bans (e.g. Irgarol 1051 and Diuron). As such, biocide-based antifouling paints are now widely seen as a bridging technology. But what could be on the other side of the bridge? There is no shortage of ideas, but the road from concept to deployment is often a long one, especially for antifouling, where effectiveness is generally measured over five-year docking intervals. Foul release coatings, a.k.a. silicone coatings, use the same principle as Teflon pans. They contain no biocides and prevent fouling by making adhesion difficult. Even if fouling is not completely prevented, such »non-stick« coatings are easy to clean. Niche areas, however, such as bow thruster tunnels and sea chests, are problem zones. The paints scratch easily, like Teflon, and fouling starts rapidly where paint got damaged. Even if not scratched, the silicone film weathers and becomes less effective over time. The star of foul release coatings seems to be waning, but with some new twists, the idea lives on. »Nano-coatings« use bio-inspired microscopic surface structures (shark skin, lotus effect, etc.). Several products are already on the market, but research is active on new ideas. The Fraunhofer institute in Hamburg, for example, is developing new coatings mimicking floating ferns, which trap a fine film of air. Hydrogel coatings (Actiguard technology) are akin to soft contact lenses. Some fouling organisms mistake the hydrogel for water; the hull surface becomes effectively invisible for them. Combined with a mechanism to trap biocides on the hull surface, this approach can reduce biocide leaching by a factor of 10–20 over conventional antifouling coatings. Or you could use hard coatings similar to what is used on cars. Then you would need to clean frequently, but robots similar to those cleaning a swimming pool may do that in the future. They just have to learn a few more tricks, most notably team work. But the technology may come faster than we first thought. Fleet Cleaner, who is already offering robotic ship cleaning in all Dutch ports since 2017, announced in 2018 that they will develop autonomous robotic cleaning. The »young challengers« are maturing with a growing number of in-service reference applications preparing the ground for wider acceptance. However, nothing happens fast in the field of antifouling. Biocide-based coating will remain king for years and maybe decades to come, but smarter schemes for the dosage of the right biocides are coming through. This is not so much about new products, it is about choosing better from what is on the shelves right now. Vendors and buyers are getting smarter, and »performance« is monitored by both sides. The leading coating vendors have just begun to tap into their data treasures on how each coating performs where under which conditions, but already we see that this new approach is impacting market dynamics. Such insights allow better consulting on which coating to pick for a given trade. Perhaps even more importantly, we have seen the growth of performance-based contracts with »pay-asyou-save« schemes. The operators seem to be just as keen on the performance monitoring of coatings. Dealing with coating suppliers and charterers alike, performance monitoring smooths the path towards better business practice. The growing transparency from data and new business schemes should benefit operators and vendors alike. SMM will offer ample opportunities to delve deeper into new antifouling solutions and smarter performance monitoring. Author: Volker Bertram, DNV GL 54 HANSA International Maritime Journal – 155. Jahrgang – 2018 – Nr. 9
Green & Efficient RESEARCH PROJECT »CLEAN« Energy 2.0 on cruise ships The research project CLEAN – a strong, industry-led association of companies and science – is working on how anaerobic technology can be tested, developed and established on board cruise ships in an energy-efficient manner. Engineers of Carnival Maritime and Martin Membran Systems are working together with scientists from the Institute of Urban Water Management and Waste Technology at the University of Hanover and the Innovations- und Bildungszentrum Hohen Luckow to test and apply promising and innovative approaches to establish anaerobic technology on board cruise ships. The Federal Republic of Germany and here the Federal Ministry of Economics and Energy support the R&D project with financial support over three years. The aim of the project is the production of biogas and thus a renewable energy source with simultaneous, environmentally friendly recycling of organic residues. »We hope that the CLEAN research project will provide innovative, sustainable solutions, especially with regard to the generation and use of energy from organic waste on board. At the same time, the remaining quantities to be disposed of are to be significantly reduced again«, says Christoph Schladör, Head of Technical Projects at Carnival Maritime. Up to now, the focus has been on the environmentally compatible disposal of organic waste. With the new project, organic residues on cruise ships, especially in the form of food waste, flotate and sewage sludge, are now treated for the first time in such a way that they can be used as biogas. »Wastewater treatment and residual material treatment are once again significantly improved«, he emphasizes. The participating scientific partners perform important preliminary work for the design of the process engineering to be tested. This includes a precise analysis of the organic residues produced on board and, based on this, laboratory and semi-technical investigations of the reactor design. »The organic substrates on board are very heterogeneous and even new substrates such as the flotates from kitchen waste water pre-treatment are added. Therefore, the experience gained from onshore installations cannot be transferred to the ship system, says Kai Schumüller, who will work on the project at Leibniz Universität Hannover. The preliminary investigations are followed by a test of the plant technology on board an Aida Cruises ship in order to demonstrate the technical feasibility. Involved in the project are Carnival Maritime, in coordination with Aida Cruises, the Institute for Urban Water Management and Waste Technology, Leibniz University Hannover, Martin Membrane Systems and the Innovations- und Bildungszentrum Hohen Luckow. n RENOLIT MARITIME at SMM, Hamburg We look forward to personally welcome you at our booth B5.523 / Hall B5 Protective Coating Films: Better performance and cost optimization with Roll Coating Technology 4 – 7 september 2018 B5.523 / Hall B5 www.renolit-maritime.com HANSA International Maritime Journal – 155. Jahrgang – 2018 – Nr. 9 55
