Decarbonising Smart Ports: A Complexity and Paradox Perspective of Sines and Leixões

Abstract

The decarbonisation of maritime transport and port infrastructure has become a central challenge in the global transition towards climate neutrality. Smart ports are increasingly positioned as innovation hubs where digitalisation, energy transition, and sustainability intersect. However, the pathways through which ports adopt and implement decarbonisation strategies remain heterogeneous and theoretically underexplored, particularly regarding how different strategic approaches emerge in practice. This paper investigates how smart ports navigate decarbonisation through the combined lenses of Complexity Theory and Paradox Theory. It addresses three research questions: (1) What factors influence the adoption of decarbonisation practices in smart ports? (2) How do these factors shape strategic responses? (3) To what extent do emerging vectors, such as green hydrogen, represent innovation opportunities within port ecosystems? The study adopts a qualitative comparative case study methodology, analysing the ports of Sines and Leixões in Portugal. Data were collected from secondary sources, including strategic plans, institutional reports, and policy documents, and analysed through thematic coding across five dimensions: decarbonisation goals, technologies, public policies, partnerships, and expected outcomes. Findings reveal that both ports are aligned with European climate objectives but follow distinct strategic pathways. Sines adopts a large-scale, infrastructure-driven approach, leveraging international energy corridors and industrial integration projects. In contrast, Leixões pursues a more decentralised and innovation-oriented trajectory, emphasising earlier carbon neutrality targets and strong collaboration with research institutions. The analysis shows that decarbonisation emerges as a complex adaptive process shaped by multi-actor interactions, while also involving persistent tensions between growth and sustainability, centralisation and collaboration, and efficiency and experimentation. These tensions are actively managed as drivers of innovation rather than constraints, enabling differentiated yet effective transformation pathways. The paper contributes in three ways: (1) it integrates Complexity and Paradox Theory in the context of sustainable innovation; (2) it provides empirical insights from a comparative smart port analysis; and (3) it identifies green hydrogen as a strategic opportunity for complementary innovation ecosystems.