Hydrogen is key to maritime industry decarbonization. But to become a viable energy source for cleaner propulsion, ship operators must first overcome hydrogen’s inherent challenges – its low mass and density, safe handling, onboard storage, and operational issues. Because hydrogen is approximately 11 times lighter than air, extraordinarily dense amounts of the substance would be necessary for ship propulsion and operations. In order to increase the hydrogen density, larger and more complex containment is required, meaning infrastructure demands on ship architecture would be enormous, complicated, and costly.
From hydrogen source to supply tank, liquid hydrogen must be either maintained in liquid form at -253° C, or in gaseous form at extremely high pressures. These storage solutions take up valuable deck space and require significant safety measures as well as a watchful eye – not ideal trade-offs for onboard marine vessels. The answer lies in a different way to get hydrogen on board, via hydrogen-on-demand systems that rely on methanol as a hydrogen carrier feedstock.
What if hydrogen could be created as needed and instantly consumed, eliminating the storage hurdles that have confounded its maritime progress? Enter methanol – a safe and manageable agent for hydrogen production. Methanol in liquid form is stored at normal ambient conditions, room temperature, and pressure, allowing custom-fit tank design for any available space. (The cylindrical shape of a pressurised tank is only required for contents under pressure, such as stored hydrogen, whereas non-pressurized tanks allow greater flexibility in tank design.)
Hydrogen on-demand and vessel design
Through methanol-to-hydrogen conversion (or reformer conversion), ship operators can generate a consistent source of pure hydrogen in a much smaller footprint. Designed as cabinet- or container-based units, commercially-available systems present a scalable, modular path to handle diverse power requirements. These systems support 10kW to 200-kW modular fuel cell systems and can be clustered to support megawatt applications, facilitating flexibility for operations such as ship propulsion, auxiliary power systems, reefer container power, and cold ironing. Because of these parameters, a very specific industry sector reflects an ideal fit in terms of power needs, for example, fishing ships, crew transfer vessels, tug/tow boats, and ferries. These workhorses of the shipping industry are poised to lead the way to decarbonisation.
With methanol-to-hydrogen reformer technology, naval architects and engineers can capitalize on unused or under-utilized onboard space for feedstock storage. Since the ship’s power system can then be distributed across the entire vessel, premium cargo and deck space can be revisualized. Rather than being relegated to the traditional engine room, a reformer system can be located on the vessel wherever most convenient, with other reformers and methanol tanks integrated ship-wide for even greater flexibility.
Can an existing vessel infrastructure capitalize on reformer systems? Current vessels can make readily make the shift, as significant retrofit is unnecessary. A working vessel can easily store liquid methanol, repurposing diesel storage tanks though through proper maintenance and thorough cleaning.
Tapping into methanol infrastructure
Methanol is commonly found in maritime ports; its proper handling is similar to that of other fuel types. It also retains liquidity at ambient room temperatures and is biodegradable and miscible in water. The substance is relatively inexpensive compared to diesel fuel and has widespread availability in seaports around the globe.
And while ammonia also provides a pathway to hydrogen, ammonia has many disadvantages compared to methanol. These include significantly more energy and temperature to reform, higher cost, higher toxicity – especially to marine life – and less accessibility and safety. Being highly toxic, ammonia is a dangerous substance that requires advanced safety protocols for secure transport, handling, and storage. This is a substantial limitation, as the infrastructure for ammonia is just not in place for widespread acceptance. The contrast between the two is further echoed by the International Maritime Organization (IMO) viewpoint on each substance: methanol is the standard for bunkering and other marine applications; ammonia has yet to be authorized.
Clearing the grey/green confusion
Grey or green methanol (which refers to the carbon impact resulting from the production of methanol) can be applied in reforming. Widely available natural gas serves as a feedstock to produce grey methanol. Used in conjunction with PEM fuel cells, the methanol-to-hydrogen process eliminates NOx, SOx, and particulate matter. This grey methanol option results in 23 to 25 percent less CO2 when compared to that of a standard diesel engine. Green methanol is the holy grail of methanol – sustainably produced with net-zero carbon output.
Although shipping operators may hesitate to leverage methanol-to-hydrogen technology – awaiting the availability of green methanol – mandates for reduced emissions loom. Many don’t realize that, in methanol-to-hydrogen reforming, the methanol can be gray and/or green, simultaneously combined in the reformer as more sustainable options come to the forefront. This provides an advantage when net-zero advances finally do arrive. As the industry anticipates new fuels, vessels already equipped with reforming technology will be well on course to avoid the carbon levies set to commence in 2023.
Hydrogen onboard…without hydrogen stored onboard
Around the world, a well-defined regulatory agenda is emerging for environmental changes in the shipping industry. Guidelines and policies are drawing attention to how critical it is to lessen carbon’s impact ahead of global mandates. So how do shipbuilders weigh the risk of adopting versus the risk of waiting to adopt greener fuel solutions? Infrastructure may be the deciding factor in this equation, steering ship operators toward methanol-to-hydrogen options. The methanol infrastructure is well-defined, proven, global, and deeply entrenched in maritime operations. In contrast, the infrastructure to support pure hydrogen technologies is not. If and when it ‘arrives,’ complexity and high cost will remain, simply due to the material handling needs of stored hydrogen.
The hydrogen challenge
It’s clear that relying on stored hydrogen solutions for propulsion will not work for the shipping industry. But that doesn’t mean hydrogen can’t play a leading role. Through methanol-to-hydrogen reforming, there is now a relatively simple and available approach to solving the inherent difficulties of stored hydrogen – one that offers excellent potential in meeting decarbonization mandates.
In an industry where vessels are assets designed to last decades, solutions must be maintainable and optimized for real-world ship operations. Hydrogen-on-demand is charting a course to clean performance that conforms to mandates, cuts carbon penalties, and prepares shippers today for a net-zero tomorrow.
Authored by Bryan Reid,chief sales officer at RIX Industries. You can connect with him at: [email protected] or www.linkedin.com/in/bryan-reid-194470a.
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