Internal pools as stepping stones: green digital ship twins and retrofitting for FuelEU compliance through pooling mechanism and contractual implications

Abstract Maritime decarbonization is a complex, multidimensional challenge that cannot be effectively addressed through the exclusive reliance on alternative fuels. While the development and integration of such fuels are essential in the long term, focusing solely on their production overlooks other viable and immediately actionable pathways. This paper particularly argues that technology (green digital ship twins) and retrofitting (Wind Assisted Propulsion Systems) offer practical and impactful solutions that can accelerate progress toward regulatory compliance—particularly under frameworks like FuelEU. The regulation itself underscores that decarbonization requires more than a singular focus, advocating for a combination of strategies to reduce emissions effectively. Crucially, these technological solutions are not only easier to implement but also align with the pooling mechanisms FuelEU promotes as a flexible compliance tool. Adopting a broader sustainability lens, this study emphasizes leveraging existing solutions over waiting for yet-to-be-developed alternatives. It highlights how applying current technologies in internal pooling systems can serve as a foundational strategy in the early stages of FuelEU implementation. While alternative fuels will undoubtedly shape the future of the maritime industry, retrofitting and decarbonization technologies present competitive and scalable options today. These approaches offer not only environmental benefits but also economic and operational feasibility. By tapping into their potential, maritime stakeholders can navigate the complexities of compliance and sustainability more effectively. This paper reviews the literature concerning shipping, technology and law, industry reports and regulatory notes. This paper proposes that these underutilized solutions form solid stepping stones, helping bridge the gap between regulatory ambition and practical implementation in the maritime sector’s journey toward decarbonization. To put it differently, the paper argues that digital ship twins and wind-assisted propulsion can help achieving gradual decarbonization targets and highlights that their application could massively support regulatory compliance especially in the context of FuelEU, through their deployment in internal FuelEU pools.