Global shipping currently contributes an estimated 3% of total greenhouse gas (GHG) emissions, with the majority emitted in international waters. As the maritime industry endeavors to reach net-zero emissions by 2050, selecting the most appropriate alternative fuel remains a central challenge. Various fuel options—such as hydrogen, ammonia, methanol, and liquefied natural gas (LNG)—have emerged, each with unique advantages and drawbacks. This blog offers an overview of these options.
The Shift Toward Low-Carbon Shipping
Reducing GHG emissions in shipping is vital not only for mitigating climate change but also for ensuring the long-term sustainability of global trade. Efforts to decarbonize maritime operations include:
- Improving Energy Efficiency: Optimizing hull designs, reducing vessel speed, and improving routing.
- Transitioning to Alternative Fuels: Testing or adopting hydrogen, ammonia, methanol, and LNG, among others.
- Blended or Dual-Fuel Solutions: Combining traditional liquid fuels with cleaner alternatives to facilitate a gradual transition.
Despite these initiatives, no single fuel type has gained universal acceptance. Each option requires careful evaluation of logistical requirements, safety implications, and cost-effectiveness.
Overview of Alternative Fuels
- Hydrogen
Hydrogen’s primary advantage is that it emits only water when used in a fuel cell or combusted properly. However, it has a broad flammability range (4-75% by volume in air) and can form explosive mixtures with air in various concentrations. Storage, transport, and bunkering infrastructure present additional challenges, particularly given hydrogen’s low volumetric energy density and cryogenic temperature requirements when stored as a liquid.
- Ammonia
Ammonia is receiving increasing attention due to its zero-carbon combustion potential and relatively established global distribution network. Key considerations include:
- Toxicity: Ammonia is hazardous when inhaled, necessitating strict handling procedures and robust ventilation.
- Corrosivity: Specialized materials are needed to store and transport ammonia safely.
- Combustion Characteristics: Although ammonia has a narrower flammability range compared to hydrogen, improper handling can result in fire or explosion hazards.
- Methanol
Methanol’s liquid state at ambient temperatures simplifies transportation and storage. However, it is still flammable and toxic, making leak detection systems and ventilation critical.
- Liquefied Natural Gas (LNG)
LNG significantly reduces particulate matter and sulfur oxide emissions but still contains carbon. LNG’s cryogenic requirements and the potential for large-scale vapor cloud explosions demand specialized vessel designs and safety protocols.
Incident Profiles and Fire Safety Considerations
Recent incidents illustrate how rapidly evolving maritime technology can outpace risk management practices. Fires on board the Felicity Ace, the Fremantle Highway, and the Genius Star XI - linked to lithium - ion battery cargo - highlight the potential severity of onboard fires in modern vessels. In the Fremantle Highway incident, crew members experienced casualties and serious injuries, underscoring the importance of robust safety protocols.
For alternative fuels, key risks include:
- Leak and Dispersion: In confined spaces, lighter - than - air gases (e.g., hydrogen) accumulate at the ceiling, while heavier - than - air vapors (e.g., LNG in certain conditions) can pool in low points.
- Ignition Sources: Delays in ignition can lead to deflagration (subsonic) or detonation (supersonic) events if a significant fuel cloud forms.
- Passive and Active Fire Protection: Ships must integrate fire - resistant materials with detection, suppression, and ventilation systems to mitigate hazards effectively.
Regulatory Developments and the IGF Code
Maritime safety regulations for low-flashpoint fuels are primarily governed by the International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels (IGF Code). This code stipulates mandatory system arrangement, installation, and monitoring requirements, which are enforced through the SOLAS Convention.
Recent amendments to the IGF Code—covering the use of ammonia as well as compressed and liquefied hydrogen—are expected to be approved by the International Maritime Organization (IMO) in September 2024, with publication slated for January 2025. These updates will clarify design, operational, and maintenance standards for alternative-fuelled vessels, reflecting the industry’s evolving needs.
Risk Management Frameworks
A comprehensive risk management strategy helps ensure that the adoption of alternative fuels does not compromise onboard safety. Widely used methodologies include:
- Hazard Identification (HAZID) – Identifies potential hazards early in the design phase.
- Hazard and Operability Study (HAZOP) – Examines process deviations and operational risks systematically.
- Layers of Protection Analysis (LOPA) – Evaluates multiple safeguards to prevent hazardous events.
- Failure Modes and Effects Analyses (FMEA) – Identifies possible failure points and their impact on system reliability.
- Consequence Modelling – Predicts the outcomes of accidental releases, including fire, explosion, or toxic exposure.
- Facility Siting – Determines optimal arrangements of critical equipment to reduce escalation risk.
- Fire and Explosion Risk Analysis (FERA) – Assesses potential ignition sources and blast effects.
- Quantitative Risk Assessment (QRA) – Assigns numerical risk values to different scenarios, guiding cost-benefit decisions.
By applying these methods in tandem, stakeholders can make informed decisions about system designs and emergency response plans, keeping risks at levels considered “as low as reasonably practicable.”
Safely transitioning to alternative fuels is integral to the maritime sector’s effort to decarbonize and meet net-zero targets by 2050. While hydrogen, ammonia, methanol, and LNG each offer unique opportunities, they also pose distinct safety challenges related to flammability, toxicity, storage, and handling. Regulatory updates, such as the forthcoming amendments to the IGF Code, will provide clearer guidance and help standardize best practices.
Ultimately, the combination of robust engineering solutions, comprehensive risk assessments, crew training, and proactive regulatory frameworks will ensure that future alternative-fuelled vessels operate safely. By remaining vigilant and scientifically grounded in safety management, the maritime industry can effectively balance its environmental aspirations with the imperative to protect human life and preserve vessel integrity.
