Comprehensive techno-economic assessment of power technologies and synthetic fuels under discussion for ship applications

The decarbonization of the global ship traffic is one of the industry's greatest challenges for the next decades and will likely only be achieved with the introduction of synthetic fuels. Until now, however, not one single best technology solution emerged to ideally fit this task. Instead, different energy carriers including hydrogen, ammonia, methanol, methane, and synthetic diesel are subject of discussion for usage in either internal combustion engines or fuel cells. In order to drive the selection procedure, a case study for the year 2030 with all eligible combinations of power technologies and fuels is conducted. The assessment quantifies the technologies’ economic performances for cost-optimized system designs and in dependence of a ship's mission characteristics. Thereby, the influence of trends for electrofuel prices and shipboard volume opportunity costs are examined. Even if gaseous hydrogen is often considered not suitable for large ship applications due to its low volumetric energy density, both the comparatively small fuel price and the high efficiency of fuel cells lead to the overall smallest system costs for passages up to 21 days, depending on assumed cost parameters. Only for missions longer than seven days, fuel cells operating on methanol or ammonia can compete with gaseous hydrogen economically.