Future of Decarbonization in Shipping: Ammonia as an Alternative Fuel

The maritime industry's transition toward decarbonization is accelerating, with alternative fuels playing a pivotal role in this shift. Among these, ammonia and methanol stand out as key drivers, offering scalable solutions for sustainable shipping in the years to come. According to DNV’s Alternative Fuels Insights platform, the sector's commitment is evident, with 27 ammonia-fueled and 322 methanol-fueled vessels currently on order. While methanol has seen faster adoption due to its simpler handling and existing infrastructure, ammonia, with its potential for zero-carbon emissions, is gaining recognition as a critical long-term solution. Although it has been safely produced, stored, and transported for decades, primarily for use in the production of agricultural fertilizers, its application as a fuel in shipping introduces new complexities. Ammonia’s toxicity, corrosiveness, and unique handling requirements place heightened demands on safety protocols, training, regulatory frameworks, and associated infrastructure including transfer systems.

Collaboration across stakeholders, from shipowners to fuel producers and regulators, will be essential to safely integrate ammonia into the global shipping energy mix. Several projects and organizations are already leading the charge in integrating ammonia as a marine fuel. For instance, the CASTOR initiative, funded by the European Union, focuses on the development of ammonia-powered ship designs and safety systems. Additionally, Maersk have announced exploratory studies into ammonia adoption, alongside their ongoing investments in methanol and LNG-fueled vessels. This is an exciting but complex chapter in maritime decarbonization, and overcoming these challenges will define the way forward.

From a regulatory framework perspective, the International Maritime Organization (IMO) is working to establish safety guidelines and operational standards for ammonia-powered vessels under its IGF (International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels) Code. These regulations are still in early development, and its widespread adoption will require significant alignment amongst regulatory bodies across the globe. Without harmonized regulations, the scalability of ammonia as a marine fuel will remain constrained.

Environmental Considerations for Ammonia​

While ammonia offers zero-carbon emissions at the point of use, its overall environmental footprint depends heavily on how it is produced. Currently, most ammonia is derived from fossil fuels, primarily through the energy-intensive Haber-Bosch process, which emits significant greenhouse gases. For ammonia to deliver on its promise as a sustainable fuel, the whole life cycle must be examined, therefore production must transition to green ammonia, synthesized using renewable energy sources such as wind or solar-powered electrolysis. Until this shift occurs, ammonia risks falling short of its full environmental potential. This means that the focus should not solely be on ammonia’s end-use but also on decarbonizing its production methods.

Solutions for Safe Adoption of Ammonia

Advanced engineering solutions will be critical to overcoming ammonia’s safety challenges. Redundant safety valves, and automated shut-off systems can reduce risks during storage and transfer. Real-time monitoring technologies that track pressure, temperature, and concentration levels are essential for identifying potential hazards in real-time. Predictive maintenance systems will also be crucial in further enhancing safety by detecting equipment issues before failures occur, minimizing downtime and mitigating risks.

SGMF have recently published their safety and operational guidelines for bunkering ammonia, taking existing handling experience and best practice to produce guidance to enable early adopters of ammonia as a marine fuel to be aware of the basic safety principles when handling ammonia as a fuel. Embedded within the transfer safety systems are the use of ESD control systems for transfer equipment, including ERC for hoses, and for bunkering safety links to be applied ensuring mutual shutdown and clear communications during the bunkering process.

A robust safety culture will be essential. Comprehensive crew training and competency assessments, regular safety drills, and advanced simulation tools like virtual reality (VR) can prepare crews for the unique risks of handling ammonia. For instance, VR scenarios could simulate a fuel leak during transfer, enabling crews to practice and respond confidently and effectively. Seamless communication and the transfer of process safety data between ship crews and counterpart facilities will be crucial to ensure safe, accurate, and error-free fuel transfers.

Way Forward

Ammonia’s potential for zero-carbon emissions positions it as a transformative solution for maritime decarbonization, but its adoption will require overcoming significant technical, regulatory, and environmental hurdles. Although methanol currently serves as a practical bridge fuel, its ability to achieve net-zero carbon status when sourced renewably could allow it to thrive alongside ammonia in the future. The future may ultimately see a coexistence of these fuels plus net-zero versions of more traditional fuels such as LNG and MDO in ‘bio’ or ‘e’ produced variants, each serving specific segments of the maritime industry based on vessel type, route, and operational needs.