The roadmap to carbon neutrality for the maritime industry: an insight into various routes to decarbonise ship engines

“Abstract

Global maritime shipping is an important driver to the global economy, accounting for 12.3 billion tonnes in maritime trade volume in 2023. Mainly driven by petroleum-based fuels, the sector emitted 706 Mt of CO2 in 2022, constituting 2 % of global CO2 emissions. The International Maritime Organization (IMO) have set greenhouse gas emissions (GHG) reduction targets with the ultimate goal of achieving net-zero by 2050 with short- and medium-term checkpoints in 2030 and 2040. Internal combustion engines shall continue to be the prime propulsion method for ships as it could meet the load requirements throughout the ship’s voyage. Therefore, meeting these targets and the increasingly strict regulations governing GHG and NOx from the exhaust must be the sole focus of future ship propulsion design. This can be achieved by adopting incrementally radical and advanced combustion technologies, from operational optimization towards retrofit of new technologies paving the way to radical redesign of thermodynamic cycles. In addition, moving away from long-chain carbon fuels towards zero-carbon fuels is the proposed pathway towards removing CO2 altogether from exhaust emission. This article proposes a roadmap towards achieving the 2050 IMO target and discusses the implementation and utilization of various fuel and engine technologies. Furthermore, this article discusses retrofit considerations, economic viability, and ports infrastructure preparedness in adopting these alternative fuels. It was reported that 36% of ships on order will adopt liquefied natural gas (LNG), signalling a promising shift to decarbonise, supported by ports around the world developing infrastructure for LNG, hydrogen, and ammonia bunkering.”

 

The full report is accessible via: https://doi.org/10.1016/j.ecmx.2025.101184

For related publications, please see Resources – UK National Clean Maritime Research Hub