Shipping sector decarbonisation measures: A review

The shipping sector faces a significant challenge in their contribution to achieving both the Paris Agreement target of limiting global warming below 2 ⁰C or even 1.5 ⁰C above pre-industrial levels and the International Maritime Organisation goal of greenhouse gas reduction in the shipping sector. Latest targets involve reducing CO₂ emissions per transport work by 40% by 2030 compared to 2008 and a full decarbonisation of emissions from vessels by 2050. This situation has driven the shipping sector to explore technological, operational and market-based approaches, which are evaluated. These measures involve a wide range of solutions such as alternative fuels, energy efficiency systems, automatic monitoring, hull optimisation, power management, slow steaming, or regulatory interventions. Alternative fuels such as LNG, methanol, hydrogen, and ammonia offer high emission reduction potential, with LNG currently the most implemented due to its economic feasibility. However, many new builds are dual-fuel, and their real impact depends on fuel supply and policy enforcement. Energy efficiency technologies and carbon capture also show strong cost-effectiveness, particularly in retrofitting existing vessels. Moreover, operational strategies like slow steaming and route optimization contribute moderately but face practical limitations. Additionally, regulatory measures like EEDI and EEXI are essential yet unevenly enforced. The gap between design-stage decarbonisation features and operational fuel usage is highlighted, meaning a current need for integrated policy, infrastructure, and stakeholder engagement. Hence, critical challenges and synergies across measures are evaluated, supporting informed decisions toward achieving IMO’s 2050 decarbonisation target and advancing Sustainable Development Goals 7 and 13.