As the maritime industry accelerates its pursuit of sustainable energy solutions, hydrogen has garnered significant attention as a potential alternative fuel, particularly in its compressed and liquefied forms (LH2).
The ITOPF, as part of the International Group of P&I Clubs’ Alternative Fuels Working Group, has undertaken the task of examining the implications of using hydrogen as a marine fuel.
According to the report titled “Fate, behavior and potential liabilities arising from a spill of hydrogen into the marine environment” the use of hydrogen as a fuel for shipping can be used in multiple states, such as liquefied or compressed hydrogen within internal combustion engines or using LH2 within fuel cells. Due to the economic and technical barriers facing hydrogen technology and infrastructure development, the industry is immature when compared to other marine alternative fuels and therefore these technologies may develop in the future, with one format potentially being more technically viable than others.
The alternative fuels covered are:
- Biofuels
- Liquefied Natural Gas (LNG)
- Liquefied Petroleum Gas (LPG)
- Hydrogen
- Ammonia
- Methanol
The use of hydrogen as a fuel for shipping can be used in multiple states, such as liquefied or compressed hydrogen within internal combustion engines, or using LH2 within fuel cells. Due to the economic and technical barriers facing hydrogen technology and infrastructure development, the industry is immature when compared to other marine alternative fuels and therefore these technologies may develop in the future, with one format potentially being more technically viable than others. For the purpose of this report, the fate, behaviour, damages and liabilities of compressed hydrogen and LH2 will be outlined. Small scale R&D projects are being undertaken in the United States, Belgium, Norway and France, and the first use of LH2 as a marine fuel was observed in the MF HYDRA ferry in Norway. In addition, four ports in Europe and one in Japan are developing hydrogen import plans.
The use of dual-fuel engines is increasingly commonplace within the shipping industry and allows for flexibility between alternative fuels such as hydrogen and more conventional fuel oils (e.g. heavy fuel oil, marine diesel oil or even biofuels). In the future, there may be potential for multiple alternative fuels to be used on the same vessel. This means that, in the event of an incident, there may be potential for multiple alternative fuels to be spilled simultaneously, which could combine the risks outlined in these summary documents. An incident of this type would require a complex and highly specialised response to be mounted to counteract these risks.
Unlike biofuels, LNG, LPG, ammonia and methanol, hydrogen is not globally transported as a marine cargo and therefore experience in handling, transportation, storage and loading/unloading is currently limited. Therefore, general understanding of hazards and risks associated with hydrogen as a marine fuel, and particularly LH2, is limited. To date, ITOPF has not been involved in a case involving a spill/release of hydrogen.
At ambient conditions, hydrogen is a colourless, odourless, non-toxic gas. Due to its very low density, hydrogen is typically liquefied or compressed for storage and transport as it takes about 1/850th of the volume of hydrogen gas. Pure hydrogen would require cooling ranging from -254 °C under 1 bar to -240 °C under 13 bars to be stored as LH2. It can also be stored as a compressed gas if subjected to very high pressures (250 – 700 bar). However, LH2 has approximately 4.5 times higher energy density than compressed hydrogen gas, making LH2 a more attractive storage option for shipping applications. Efforts are being made to use a combination of the two dominant storage options to optimise the cost and volume of storage.
Hazards of hydrogen when spilled in the marine environment
Hydrogen’s hazards can lead to direct impacts on health and safety, mainly through its flammability and explosivity.
Flammability
LH2 is not flammable, however, its vapour has a flammability range of 4 – 75 (v/v) %, which can be detected with specialised equipment. Outside of this range, the hydrogen/air mixture is not flammable. This is greater than conventional fuels such as diesel, which has a much smaller flammability range of 0.6 – 5.5 (v/v) %. In an unconfined space, a release of LH2 from a tank or pipeline will rapidly mix and dissipate into the atmosphere reaching concentrations below the 4% LFL. Only a small area near the immediate leak would likely reach the concentration that would allow hydrogen to ignite.
In a confined space, where flammable vapours cannot dissipate, a small leak would result in a stratified layer of hydrogen at high points in that space (e.g. at ceiling height), which could lead to a flammable vapour/air mixture. Note that inside a fuel storage tank, the percentage of hydrogen is almost pure and, as such, the conditions are not in its flammable range. However, following a leak/rupture, a vapour cloud will form and once it has mixed with air, when its concentration reaches between the LFL (4% volume) and the upper flammability limit (UFL) (75% volume), the mixture can sustain a flame if ignited. If ignition occurs immediately, a flash fire is likely to result and continue until all the fuel is consumed. It should be noted that hydrogen-air flames are colourless and therefore have a low visibility, especially in daylight conditions. Hydrogen fires also have a low radiant heat and therefore, it is difficult to sense the location of the fire until in close proximity.
Conclusions
Claims from clean-up and preventive measures are expected to arise from different measures, such as source control, fire-fighting measures, monitoring via expert modelling or sensors mounted on UAVs/ROVs and possible bunker fuel removal. Traditional clean-up measures will not be possible and therefore, claims from a protracted spill clean-up operation will not arise. However, personal injury and loss of life claims may be significant. Risks from fire, explosions, cryogenic damage and asphyxiating vapours could lead to death or life-altering injuries to crew, passengers, nearby operators and members of the public.
Claims arising from environmental damage are likely to be geographically confined in comparison to damage from oil spills. Post spill studies may be undertaken, in certain circumstances, to establish the severity and extent of damage. Restoration measures are likely to be minimal and confined to a small area. Rather than property damage claims involving cleaning and cosmetic repair of oiled property, LH2 claims are likely to be a result of fire, explosion or cryogenic damage and therefore, structural repair or replacement may be required, which would likely be more costly and potentially time-consuming.
Economic loss claims resulting from a fire or explosion could include port closure/disruption and associated demurrage costs, losses from damaged/destroyed property, local aquaculture losses from mortality of stock, and local losses resulting from fishing bans. Impacts to commercial water intakes and tourism may also occur.