Efficiency and emissions of a high-speed marine diesel engine converted to dual-fuel operation with methanol

Climate change and global warming, a growing maritime sector, and the roadmap away from fossil fuels towards a CO2 neutral economy are driving innovations and technology developments. Fuel selection criteria such as sustainability, scalability and storability, lead to the selection of methanol as a viable alternative for fossil fuels. In LeanShips, a European Horizon 2020 Innovation Project, the conversion and operation of a high speed marine diesel engine on dual fuel methanol/diesel has been demonstrated. This paper presents the applied conversion solution, its impact on combustion characteristics, and the results of dual fuel methanol/diesel operation on engine performance parameters such as brake thermal efficiency (BTE), NO and soot emissions. The results were recorded at different engine speeds ranging from 1000 to 2000 rpm and for varying loads, in total 28 load points were tested. At each load point the methanol energy fraction was increased until the boundaries for substitution were reached. In dual fuel operation a relative increase of 12% in BTE was recorded and for respectively NO and soot emissions average decreases over the entire load range of 60% and 77%. The maximum obtained methanol energy fraction and diesel substitution ratio amounted respectively to 70% and 67%.