Sustainable Maritime Fuels: Hydrogen, Fuel Cells, and Decarbonization

The global shipping industry- accountable for about 3% of greenhouse gas emissions- is under pressure to cut carbon drastically. International regulations (IMO’s 2050 Vision) call for at least a 50% emissions reduction by mid-century. In response, engineers and shipowners are researching a range of clean fuel technologies. Hydrogen stands out as a zero-emission fuel that can be produced ecologically. For example, advanced compressed hydrogen storage system enable vessels to securely pack hydrogen gas into high-pressure tanks for later use. Combined with built in hydrogen fuel cells they hold a promise of a truly zero-emission propulsion without range/power trade-offs. 

The use of hydrogen fuel-cell technology involves hydrogen and oxygen being converted into electricity as its only byproducts are just water (H 2 O) and heat. Contemporary fuel cells (typically Proton-Exchange-Membrane, or PEM, nature) are also efficient, compact and scalable. They do not generate any amount of CO 2, NO x, SO x, or particulate matter, thus helping the attainment of stringent limits on emission. For instance, Proteus Energy’s new maritime fuel cell solution relies on modular PEM fuel-cell stacks (each ~75 kW) that can be combined to match a vessel’s power needs. Nearshore ferries to harbor tugs can incorporate such fuel-cell modules into real world operations. Hydrogen cells too are also silent and require less maintenance as compared to diesel engines. 

Key Benefits of Hydrogen Fuel Cells

High Energy Density: Fuel cells produce smooth, robust power, enough to serve as propulsion or supplementary power, which hydrogen is highly gravimetrically energy dense. 

Zero Emissions: Fuel cells emit only water and heat. All carbon and pollutant emissions (CO₂, NOₓ, SOₓ, particulates) are eliminated.

Low Maintenance: Hydrogen fuel cells reduce the cost of maintenance and increase the service life as compared to diesel gensets since they require very few moving parts and there is no combustion..

Quiet Operation: Fuel-cell engines are quiet and have no vibrations, which makes the experience on board more comfortable and ensures fewer noise emissions. 

Fuel cells can improve the economics with fuel savings, incentives, and carbon control despite increased up-front costs. Analyses point to the fact that fuel-cell systems would be able to rival diesel once carbon pricing and efficiency measures are introduced.

Hydrogen Storage and Refueling

A critical challenge is onboard storage. The volumetric energy density of Hydrogen is low; therefore, large or high-pressure tanks are required. The most mature of available options is high-pressure (compressed) hydrogen storage. High-pressure hydrogen tanks are now approved by classification societies (DNV, ABS, etc.) to be used in the maritime industry. For example, Norway’s TECO 2030 earned DNV Approval in Principle (AiP) for its containerized compressed-H₂ fuel-cell system, validating the viability and safety of its all-in-one bunkering, storage, and fuel supply design. Likewise, Proteus works with partners (Forvia) to produce DNV-type approved 350 bar composite tanks that store hydrogen safely onboard. 

Compressed vs. Cryogenic: Compressed tanks at room temperature and ~350–700 bar pressure. They are simpler and widely proven, though bulky. Liquid hydrogen (-253 o C) is more dense but introduces more complexity and boil-off losses. Depending on the type of ships, the option might vary: short-sea ships tend to operate with compressed tanks, whereas long-range ships might utilize liquid hydrogen or hydrogen carriers (ammonia, LOHCs) upon maturation of technology. 

Safety and Advances: Modern hydrogen systems meet strict maritime safety standards. They feature double-walled piping, pressure relief valves, and automated leak detection. Storage designs continually improve – tanks and refueling interfaces are becoming more compact, insulated and efficient. Ports worldwide are beginning to build hydrogen bunkering (refueling) facilities. (For example, Switch Maritime’s Sea Change ferry was recently refueled with green hydrogen in the US, marking a milestone. 

Additionally, shipping is exploring hydrogen carriers. Ammonia and methanol can carry hydrogen in liquid form and can be cracked back to hydrogen in situ. But all pathways rely on producing low-carbon (green or blue) at scale. Regions like Singapore are investing in hydrogen import and storage infrastructure to support their maritime sectors. 

Real-World Trends and Case Studies

Hydrogen fuel-cell vessels are moving from concept to reality. In Norway, the MF Hydra ferry (2022) became the first passenger/car ferry powered by liquid hydrogen and Ballard fuel cells, sailing between Stravanger and Bergen. In the In the US, the “Sea Change” hydrogen ferry (2023) demonstrated PEM fuel cells on a harbor ferry, achieving ~20 knots and quietly running with no exhaust. Switch Maritime reported it as “the first commercial vessel … under hydrogen fuel cell power”. Experts there predict fuel-cell propulsion could become standard for many vessels within a decade.

Other examples include:

• Port and harbor craft: Projects like Port of Gothenburg’s HyFlex system (2024) powered cranes and shore equipment with a 100 kW hydrogen fuel cell, proving reliability in port operations.

• Containerized fuel-cell modules: TECO 2030’s AiP-rated containers can be retrofitted on ships and in port for flexible power, akin to today’s generator sets.

• Global push: Asia and Europe are also active. The decarbonization of shipping is identified as one of the solutions that can be implemented through hydrogen, according to the National Hydrogen Strategy of Singapore. Shipbuilders in China and Japan are trying to envision vessels using hydrogen or ammonia in a few years, based on their expectations of significantly tougher emissions regulations.

These pilots and partnerships show that hydrogen and fuel cells are more than theoretical – they are being engineered and tested now. Classification bodies (DNV, Lloyd’s, CCS) have already issued the first standards for hydrogen fuel and fuel-cell ships, and hydrogen bunkering procedures are under development.

The Road Ahead for Maritime Hydrogen

There are obstacles still (infrastructure deployment, gas cost, retrofit), but progress is gathering pace. Hydrogen shipping is being incentivized and funded by governments and ports. The very technology is being enhanced: decades of automotive and stationary applications are already leading to more reliable and cheaper fuel-cell stacks. Concurrently, the green hydrogen costs are falling due to the growth of renewable sources of energy.

A clear implication to the maritime stakeholders is that hydrogen fuel cells have a scalable and clean alternative to most types of vessels (particularly short-range and harbor vessels). The ports that invest in hydrogen bunkering today are able to win the attention of the so-called early adopter ship operators that pursue the reduction of emissions. Shipowners who start planning will be able to embrace hydrogen systems over time with the inclusion of new constructs or retrofit. This is a strategic strategy in line with sustainability objectives (e.g. IMO 2050) and in the future is likely to overlap with carbon pricing or regulation.

To recap it all, sustainable fuel technologies such as hydrogen are taking a speedy step closer to practice, rather than theory. Due to the likelihood of fuel cells to reach the efficient stage, and the potential of secure hydrogen storage (e.g. in compressed tanks or carriers), the maritime industry could have zero-emission propulsion. Hydrogen fuel cells on ships, as one analysis observes, have a potential to tremendously reduce the carbon dioxide and other pollutant emission rates (British Medical Journal 2007). With regulatory pressure and technology synergies, decision-makers in shipping are wise to watch and engage with these emerging solutions today.