Clean Seas, Green Ships: The Future of Maritime Decarbonisation

Maritime decarbonisation is one of the biggest challenges in transport today. While aviation has gained momentum with Sustainable Aviation Fuel (SAF) and the coordinated efforts of the Jet Zero Council, the shipping industry remains fragmented. As the UK government prepares to refresh its Clean Maritime Plan, there is a pressing need to address two critical gaps: the absence of a sustainable fuel equivalent and the lack of a unified strategy to drive progress. However, beyond these specific challenges, the broader reality is that maritime faces a far more complex path to decarbonisation than aviation, with a host of obstacles spanning fuel technology, infrastructure, and the unique requirements of different vessel types.

A Complex Transition with No One Solution

Unlike aviation, which has largely coalesced around system improvements, followed by SAF, followed by hydrogen as a viable pathway to reducing emissions, the maritime sector has yet to settle on a dominant alternative fuel. The industry is currently exploring multiple options, each with its own advantages and limitations. Green ammonia, while offering zero-carbon combustion, poses serious toxicity and handling challenges. Green methanol is seen as a promising solution due to its relative compatibility with existing infrastructure, but its production capacity remains limited. Hydrogen, often touted as a zero-emission fuel, faces significant hurdles in storage and bunkering, making it more viable for short-sea shipping than for deep-sea voyages. Biofuels offer a near-term alternative, but concerns over sustainability and supply constraints limit their long-term potential. Nuclear power is another possibility, particularly for large vessels, yet regulatory, safety, and public perception challenges remain formidable barriers to adoption.

The absence of a clear frontrunner creates a major issue for shipowners and operators. The risk of investing in vessels that could become obsolete if the wrong fuel pathway is chosen has led to hesitancy across the industry. Unlike aviation, where airlines are backing SAF even as hydrogen and electric concepts develop, maritime is still in an uncertain, fragmented phase with no single technology emerging as the preferred route forward.

Infrastructure is Not Ready

Even if a dominant alternative fuel were identified, the global maritime infrastructure is nowhere near ready to support large-scale adoption. Today’s ports and bunkering facilities are designed for fossil fuels, and adapting them for new fuels requires enormous investment. Ammonia, methanol, and hydrogen each require entirely different storage and safety measures, meaning that infrastructure upgrades are not just costly but also complex. Retrofits will be needed not just at a few key ports but across a global network, adding another layer of uncertainty to an industry that relies on seamless refueling operations at multiple locations.

Standardisation is another challenge. Without international coordination, different ports may adopt different fuel strategies, leaving shipowners with a logistical nightmare. A fragmented approach could see vessels unable to refuel efficiently, forcing operators to hedge their bets by developing multi-fuel vessels—a costly and impractical solution.

Shore Power: The Silent Bottleneck

Electrification is often cited as a decarbonisation tool, but shore power remains severely underdeveloped. Ships continue to rely on onboard diesel generators while docked, contributing to emissions in ports and surrounding areas. While connecting vessels to grid power could eliminate these emissions, the infrastructure is woefully lacking.

Most ports simply do not have the grid capacity to handle widespread shore power adoption. Retrofitting terminals and upgrading electrical networks requires significant investment, while shipowners also need to modify vessels to be shore-power compatible. Even where infrastructure is available, the lack of standardised connection formats creates compatibility issues. Without a coordinated push to improve grid readiness, shore power risks remaining a niche solution rather than a mainstream decarbonisation tool.

Different Sectors, Different Challenges

Unlike aviation, where almost all commercial aircraft use the same fuel, the maritime industry operates a diverse range of vessels with vastly different energy demands. Cruise ships, with their high hotel-load energy requirements, may be better suited to nuclear or alternative fuels rather than batteries. Container ships, which need long-range, scalable fuel solutions, are more likely to rely on ammonia or methanol. Tankers and bulk carriers, operating long-haul routes, require high energy density, making battery-electric propulsion unviable. Workboats and ferries, by contrast, can more readily transition to battery-electric or hydrogen solutions due to their shorter operating ranges.

This diversity makes maritime decarbonisation far more complex than aviation’s SAF transition. A single, unified fuel solution is unlikely to emerge, meaning that multiple technologies must be developed and commercialised in parallel. This further complicates investment decisions and regulatory frameworks, making it even more essential for the industry to establish a coordinated approach.

SMF - The Need for a Maritime Equivalent to SAF

The aviation sector’s success with SAF has been driven by clear government backing, industry buy-in, and financial incentives to support early adoption. Maritime needs the same level of commitment to ensure the commercialisation of alternative fuels. Government policy must provide long-term certainty to investors, while the industry itself must send a strong demand signal to fuel producers. Without coordinated action, the maritime sector risks falling even further behind, struggling with fuel uncertainty while other transport sectors accelerate their decarbonisation efforts.

A Jet Zero Council for Shipping

One of the most effective tools in aviation’s decarbonisation strategy has been the Jet Zero Council, which has brought together industry leaders, policymakers, and researchers to align efforts and drive progress. Maritime lacks a similar body, leaving the sector without a unified voice to push for regulatory clarity, funding mechanisms, and infrastructure development. The absence of a coordinated forum has led to fragmented efforts, slowing the pace of progress.

A dedicated Maritime Zero Council could provide the structure needed to unify the industry, set clear decarbonisation milestones, and ensure that government and private sector efforts are aligned. By establishing common objectives and securing long-term policy support, the industry could overcome many of the roadblocks currently hampering progress. Without such a body, maritime risks a disjointed transition where progress is piecemeal and insufficient to meet net-zero targets.

Conclusion

The refreshed Clean Maritime Plan presents a critical opportunity to set a bold vision for maritime decarbonisation. But to succeed, the industry must tackle two fundamental gaps: the lack of a sustainable fuel equivalent to SAF and the absence of a coordinated strategy akin to the Jet Zero Council. At the same time, the sector must confront deep-rooted challenges, from infrastructure and fuel uncertainty to the diverse energy needs of different vessel types.

Without decisive action, maritime risks being left behind in the global energy transition. The industry cannot afford to wait for a perfect solution—it must act now to drive innovation, standardisation, and investment. The pathway to zero-emission shipping is complex, but with the right policies, collaboration, and leadership, it is within reach.