Decarbonizing the Port of Sines: An Integrated Approach Combining Stakeholder Input and Life-Cycle Assessment

Port decarbonization strategies often prioritize emissions under direct port authority control while overlooking dominant indirect sources. This study proposes an approach that combines Life-Cycle Assessment (LCA) and expert elicitation. While existing studies often rely on descriptive emission inventories, this paper demonstrates the value of combining quantitative life-cycle data with expert judgment. The methodology is applied to the Port of Sines, Portugal’s largest port by cargo volume and handling capacity. The LCA revealed that Scope 3 emissions account for over 99% of total greenhouse gas emissions, with ocean-going vessels as the main contributors. The expert elicitation process prioritized energy-related measures such as renewable energy, alternative fuels, electrification, and energy efficiency, while onshore power supply and ship–port interface measures received lower priority. By comparing the results, the study reveals a misalignment between the most significant emission sources (Scope 3 emissions, particularly ocean-going vessels) and commonly prioritized decarbonization measures (measures addressing Scopes 1 and 2). The main contribution lies in combining LCA findings and expert inputs to actively inform strategic decision making, helping ports realign decarbonization strategies toward high-impact measures and providing transferable insights for other ports pursuing net-zero objectives.