Assessing the decarbonization roadmap of a RoPax ferry

The reduction of emissions from shipping is necessary to combat climate change. One viable option is to change the fuels utilized. In this study, we investigate the environmental and economic performance of marine diesel oil (MDO), liquified natural gas (LNG), liquified biogas (LBG), and a mixture of LNG and LBG. We study a real case of a roll-on/roll-off passenger ship (RoPax) in Finland. Life cycle thinking is applied to assess the environmental impact, covering emissions from well to propeller (raw material extraction, fuel production, transportation, storage, and combustion), while the economic implications are estimated through future fuel prices and carbon pricing from 2023 to 2050. The carbon pricing covers different carbon tax schemes, namely stated policies scenario (STEPS), sustainable development scenarios (SDS), and net-zero emissions (NZE). STEPS reflects the existing measures and policies under development; SDS pursues to meet the goal of Paris Agreement, while NZE aims to reach net zero. Adopting LNG would improve carbon dioxide emissions, but the overall climate change impact was not significantly lower than MDO. It is also found that the biggest environmental improvement can be obtained by switching to LBG, although future availability can be an issue. The economic assessment shows that LBG has the highest fuel price uncertainties, although its carbon cost will be the lowest. Alternatively, using LNG & LBG mixture can serve as a transition path to contain climate change while dealing with its price uncertainty and availability.