A new perspective at the ship-air-sea-interface: the environmental impacts of exhaust gas scrubber discharge

As shipping traffic continues to increase, there is growing concern about the impacts this may have on the marine environment ranging from species-level to ecosystem services. Commercial shipping uses low-cost heavy fuel emitting significant amounts of sulphur, nitrogen, metals, organic compounds and aerosols to the atmosphere during combustion (Eyring et al. 2005). As most of these compounds have a limited residence time in the atmosphere they are deposited relatively close to the source and dissolve in the surface ocean. Several abatement techniques exist for achieving the required emission limits included in MARPOL Annex VI and EU Sulphur Directive EU 2012/35 such as novel engine technologies, exhaust gas recirculation or fuel emulsifiers etc. Open-loop exhaust gas cleaning systems (‘scrubbers’) belong to the commonly used and cheaper technologies (as alternative to expensive low-sulphur fuel for shipping companies) but are ecologically questionable

A new perspective at the ship-air-sea interface: the environmental impacts of exhaust gas scrubber discharge

Shipping emissions are likely to increase significantly in the coming decades, alongside increasing emphasis on the sustainability and environmental impacts of the maritime transport sector. Exhaust gas cleaning systems (“scrubbers”), using seawater or fresh water as cleaning media for sulfur dioxide, are progressively used by shipping companies to comply with emissions regulations. Little is known about the chemical composition of the scrubber effluent and its ecological consequences for marine life and biogeochemical processes. If scrubbers become a central tool for atmospheric pollution reduction from shipping, modeling, and experimental studies will be necessary to determine the ecological and biogeochemical effects of scrubber wash water discharge on the marine environment. Furthermore, attention must be paid to the regulation and enforcement of environmental protection standards concerning scrubber use. Close collaboration between natural scientists and social scientists is crucial for progress toward sustainable shipping and protection of the marine environment

Towards biomimetic air retaining ship hull surfaces - AIRCOAT and its experimental and computational validation methods: Presentation held at VIII International Conference on Computational Methods in Marine Engineering, MARINE 2019, Göteburg, 13 May 2019

Air lubrication has a high potential to reduce skin friction of ship hulls. Active air lubrication system are already available on the market and initial results could show significant long-term energy savings of 4 %. The EU project AIRCOAT (Air Induced friction Reducing ship Coating) aims to develop a passive air lubrication technology inspired by Salvinia molesta, a floating water fern that forms a permanent air layer when submerged in water. AIRCOAT will technologically implement this natural phenomenon to produce a biomimetic hull surface with a high potential to significantly reduce the frictional resistance of ships. The air retaining surfaces based on the Salvinia effect rely on a complex micro- and nanostructured surface with hydrophobic and hydrophilic characteristics. Transferring such characteristics onto sea going ships (e.g. container ships) – which are the largest maritime macrostructures – and demonstrating its effectivity within a three-year project is an ambitious task that involves a well-defined validation method. The AIRCOAT project does this by means of combining experimental and numerical methods to upscale results from laboratory prototypes to application of full-scale solutions in operational environments. Small- and large- scale laboratory experiments will investigate the air retaining and friction reducing capabilities of the surface. Visualisation techniques will be used to determine the phenomena occurring at the ship-air-water interface. In parallel a set of numerical studies at different levels (small, large and full scale) will be carried out to estimate the drag reduction for a sea going ship virtually coated with AIRCOAT. This contribution will introduce into the AIRCOAT project, elaborate on biomimetic air-retaining surfaces and outline the validation concept developed to quantify potential friction reduction

Der bionische Schiffsrumpf

Schon lange bedienen sich Erfinder dem natürlichen Vorbild, um technische Herausforderungen zu lösen. So einfach wie es klingt, ist es aber nicht, da die hochkomplexen biologischen Strukturen nicht einfach technisch kopiert werden können. Da bionische Lösungen dennoch riesiges technisches Potential besitzen forschen Verbundvorhaben weiter – auch an bionischen Schiffrümpfen