Regulatory Drivers of Alternative Fuel Infrastructure for Maritime Decarbonization in the European Union

The decarbonization of maritime transport requires low- and zero-greenhouse-gas fuels together with timely deployment of supporting infrastructure in ports. This study examines how the European Union (EU) regulatory framework influences strategic investment in alternative fuel infrastructure under technological and market uncertainty. A qualitative research design combines documentary analysis of EU legislation, International Maritime Organization (IMO) policy, institutional reports and peer-reviewed literature with an illustrative case study of the Port of Piraeus. A Regulatory Infrastructure Assessment Framework (RIAF) is developed around four interrelated dimensions: regulatory certainty, economic incentives, technological neutrality and port governance. The findings show that infrastructure investment is shaped mainly by the interaction of complementary EU instruments, particularly FuelEU Maritime, the Alternative Fuels Infrastructure Regulation, the EU Emissions Trading System and the revised trans-European transport network framework. Continuing IMO negotiations in 2026 demonstrate that global regulatory uncertainty remains relevant to investment expectations. The Piraeus case further shows how EU regulation, finance, governance capacity and technological flexibility interact at port level. Effective maritime decarbonization therefore depends on an integrated regulatory architecture that aligns fuel demand, infrastructure supply, economic incentives and institutional implementation.