Shipping decarbonization pathways assessment by solving Tramp Fleet Renewal and Retrofit Problems

This paper evaluates the efficacy and efficiency of fleet decarbonization pathways.We compare three different regulatory approaches, including the recent International Maritime Organization (IMO) Net-Zero Framework. To compare each pathway, we define a Strategic Tramp Fleet Renewal and Retrofit Problem with emission reduction integrated with tactical and operations decisions. The strategicdecisions are the power system and fuel selection for the fleet over the planning horizon. The tactical and operations decisions include the fleet deployment and the transportation demand satisfaction. We analyze a case study using data from a tramp shipping operator, where diesel, LNG, ammonia, LPG, and methanolare the available fuels. The experimental results confirms thatBio-methanol and E-ammonia are most relevant alternative fuels to achieve consistent emissions reductions. We conclude by discussing the different trajectories’cost-efficiencies, observing that the IMO Net-Zero Framework is very expensive forshipping operators, and the marginal contribution of the most relevant fuels.