Decarbonization effect evaluation of dual-fuel solutions for shuttle tankers using the energy efficiency design index

Ships propelled by traditional marine fuels can benefit from enhancements such as hull form optimization and structural weight reduction; however, these have limited effect on the Energy Efficiency Design Index (EEDI). Dual-fuel power solutions are increasingly used in new ship builds. In this study, a 154,000-ton shuttle tanker powered by liquefied petroleum gas (LPG), liquefied natural gas (LNG), and fossil-based methanol as low-carbon fuels is considered to evaluate dual-fuel power solutions. The decarbonization effect of each solution is determined using a tank-to-wake approach based on EEDI, without considering the well-to-tank phase of fuel types. When using low-carbon fuels as non-primary fuels, the LNG–diesel combination reduces EEDI by 9.97% compared to the diesel solution, outperforming the LPG–diesel and methanol–diesel solutions by 4 and 14 times, respectively. When using low-carbon fuels as primary fuels, the LNG–diesel solution reduces EEDI by 20.80% compared to the diesel solution, significantly outperforming the other two solutions.