Reducing particle emissions from marine engines – fuel choices and technology pathways

Particle emissions from marine applications have been receiving increasing attention in recent years, whether as black carbon for their impact in artic ice melting and global warming, as nanoparticles for their health impact or due to the general classification of soot as a carcinogenic substance by the World Health Organization. Fulfiling the global requirements of marine propulsion and power generation applications only a few technology paths are commercially available which have the potential to reduce particle emissions significantly. SOX scrubber in combination with traditional HFO operated diesel engines represent one route trying to achieve this objective. Alternatively, the engines can be converted to dual fuel operation, including liquified natural gas (LNG) operation or the fuel can be changed to a distillate liquid fuel which can be combined with a diesel particulate filter (DPF). In detail, these different approaches vary not only in terms of technical challenges, required onboard modifications and costs, but also with regards to their actual performance in reducing black carbon (BC), particle mass (PM) and nanoparticle-related particle number (PN) emissions. In the European Union the PN abatement performance will gain additional attention as in upcoming regulations a cutoff level for ultra-fine nanoparticle emissions of 10 nm will likely be introduced. In this contribution we present a comparison of the different technological options for low BC, PM & PN with their respective challenges and performance characteristics. Measurements have been conducted on marine medium-speed and high-speed engines on both engine test beds and on board. The setups were chosen in a way to cover the range of commercially available paths to reduce particulate emissions. For the measurements a range of analytical devices for assessing particlerelated emissions (together with gaseous emissions measurements) were employed. Results are set in context of current and upcoming emission regulation for international, near-coast and inland water marine applications.