Predicting optimal grid stability and welfare in onshore power supply (OPS)

Onshore Power Supply (OPS) allows ships at berth to use electricity from the onshore grid instead of relying on auxiliary diesel engines. This reduces emissions, noise, and local air pollution in port areas. Despite its growing importance for maritime decarbonisation, OPS deployment creates a coordination problem involving welfare, investment efficiency, and grid stability. We address this problem by developing a multi-objective optimisation model that combines demand-elasticity functions with swing-equation dynamics to capture the interaction between market design and electricity network conditions. Our analysis shows that existing market designs face important limitations. Specifically, the two “Intermediary” market designs pose risks of monopoly pricing and inefficient investment, while “Facilitator” market designs improve welfare but compromise grid stability. To address these problems, we propose a new “Extension-to-Grid” market design, in which the electricity network operator assumes a coordinating role. This achieves a welfare-superior balance between efficiency, stability, and consumer protection. Through illustrative scenarios, real-world pricing data and a case study with two ports in Greece, we demonstrate how the proposed model can help avoid distorted price signals or blackout risks under poorly designed OPS market structures.