H2 ICE
Fact Sheet N 2
Key Facts
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Monofuel H2 is theoretically emission free, might need SCR
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Hydrogen-Diesel co-combustion can significantly reduce CO and CO2 without NOx penalty
Funded by the Horizon Europe Programme of the European Union under grant agreement No 101096809
Funded by the Horizon Europe guarantee of the United Kingdom, under project No 10068310
Funded by the Swiss State Secretariat for Education, Research and Innovation
Catalogue of
Greening Technologies
Edition I - October 2024
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H2 ICE
FACT SHEET N 2
Emission compared to conventional diesel
The global GHG emissions are dependent on the hydrogen source.
neutral
better
Introduction
Not only can hydrogen be used for a fuel cell but also for various forms of the classic internal combustion engine (ICE). Lately manufacturers have started the development of commercially available monofuel hydrogen combustion engines. In contrast to the fuel cell or the battery, no rare-earth metals are needed to produce the combustion engine. An internal combustion engine burning hydrogen can work on the Diesel or the Otto cycle. Additional benefits are that combustion engines are cheap, can use lower quality fuel and are more easily maintained with the existing dealer/support network (compared to fuel cells). As they represent a variation to existing technology rather than a completely new power source, the acceptance by the wider industry may also be easier.
Emissions
When talking about emissions, there are initially different ways of looking at them: On the one hand, a distinction is made between toxic and climate-impacting emissions. On the other hand, a distinction is made between local and global emissions. Examples of toxic emissions are nitrogen oxides, particulates, formaldehyde, etc., while climate-impacting emissions include CO2, methane, laughing gas, etc. Local emissions have effects on the immediate surroundings of the source, such as toxicity. The effects of global emissions are not limited locally; they can be climate-impacting substances, for example, or the now banned CFC, which damages the ozone layer or sulphur emissions from the seagoing sector.
If the emissions caused by a propulsion technology or an energy source are to be assessed, there are again various approaches. The most common are the well-to-wake and the tank-to-wake approach. In the well-to-wake approach, the emissions from the entire upstream chain required for the production and supply of an energy carrier are considered. For an engine, a fuel cell or a battery this approach is called Life-Cycle-Analysis. The tank-to-wake approach looks at the emissions generated by the ship during use. Everything that happened before the energy carrier, storage system or energy converter came on board is excluded. These two definitions can produce very different results in the assessment of the technologies. For example, when considering the overall chain, the choice of a methanol combustion engine could be better than that of a battery-electric drive. This is the case if the production of the battery causes more emissions than the combustion of methanol. It is important to note that this type of consideration is also different for each ship and depends on its operating time and energy requirements. The following table shows the relevant emissions for this fact sheet.
Regulations
Currently, the introduction of hydrogen internal combustion engines for the inland waterway sector faces one major barrier: so far, hydrogen has not yet been included as reference fuels in the NRMM directive. This means for the OEM that it is not allowed to bring these engines on the market. In ES-TRIN 2025, no type approval for the engine required under exemption in accordance with Article 9.01 (6) with the restriction that the inland navigation vessel certificate shall not be valid for longer than the duration of the field test in accordance with Article 34 of the NRMM-Regulation. (This is of course still a major limitation as an INVC can only be obtained for a duration of 24 months with a single possible extension of another 24 months – in total only 4 years with currently no perspectives for further legal operation).
It is not clear how this impacts an engine which could be operated in ‘normal’ diesel (and is compliant with stage V) and which could also operate in dual fuel mode.
The technical requirements for the storage of hydrogen are foreseen in ES-TRIN 2027 Chapter 30, Annex 8, Sections 2.3 and 3.4.
Passenger Vessel
So far, there are no specific requirements foreseen for passenger vessels with H2 propulsion systems, however, the presence of passengers on board has to be taken into account in the risk assessment to be performed in compliance with Article 30.04 of the ES-TRIN.
ADN
H2 propulsion systems will be covered by the general exemptions of paragraphs 7.1.3.31 (use of engines) and 9.x.0.31 (rules for construction) once the respective requirements are adopted, meaning that a separate derogation in accordance with section 1.5.3 of the ADN would not be necessary.
However, for H2 propulsion systems benefitting from a derogation under the ES-TRIN framework, an additional derogation under the ADN framework would be required for vessels intended to carry dangerous goods.
Technical Concept
Hydrogen as Fuel
Hydrogen is typically supplied commercially in a form suitable for fuel cell applications which have a very high purity requirement such 99.999 (the so called “Five 9’s”). This makes the production, processing, and handling of hydrogen more expensive in order to maintain this high purity grade. Combustion engines have the attractive quality that they are able to utilise hydrogen at much lower purity levels.
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H2 ICE
FACT SHEET N 2
- SPI (Single Point Injection) – Hydrogen is injected upstream on the intake so that when the intake valve opens, a fully pre-mixed homogeneous fuel-air mix is ingested into the engine. Benefits are that the mixture is ideal, drawbacks are that the hydrogen displaces some air in the intake and it can be difficult to control backflash. Hydrogen supply pressure is typically ‘low’.
Figure 1: Hydrogen-Diesel co-combustion in a Diesel-engine
The lower purity requirement also means there may be a possibility to use other green fuels such as green ammonia as a storage vector for the hydrogen which can be dissociated at the point of consumption. Also the use of another hydrogen carrier such as LOHC (liquid organic hydrogen carrier) of LICH (liquid inorganic hydrogen carrier) are future options.
Engine Types
The wide ignition limits of hydrogen theoretically allow wider combustion control over the entire operating range of the engine. In contrast to conventional fuels, hydrogen can theoretically be burned homogeneously up to an air ratio of λ = 10 (i.e. 10 times more air than is required for stochiometric combustion which is 34:1 by mass). As with conventional fuels, the required ignition energy increases with the air ratio. To ignite a stoichiometric hydrogen-air mixture, only one tenth of the energy required to ignite a gasoline-air mixture is needed. In contrast, the auto-ignition temperature of hydrogen is significantly higher than that of conventional liquid fuels. Due to the very low ignition energy required, hot spots and mixing with hot gases are a particular concern for the practical control of pre-ignition problems. Although the high autoignition temperature can bring advantages in terms of knocking behaviour in the case of premixed combustion, it requires very high compression ratios or other measures to increase the charge temperature in the case of the auto-igniting hydrogen engine (i.e. a compression ignition monofuel concept) which is why this engine concept is currently deemed impractical. For these reasons, monofuel engines are typically spark ignition and there are several commercially available alternatives on the market now. The Figure 1 presenting a principle of co-combustion of hydrogen-diesel in a diesel-engine while Figure 2 shows four different variants of hydrogen combustion engine principles.
- Pressure reduction system
- Vent system
- Purge system
- Check valves
- Refueling receptacles, etc.
- H2 Tanks (fixed or swappable, see Fact Sheet “Fuel Cells”)
- Double-walled pipes, if necessary
- Thermal pressure relief devices
- Control valves
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Compression ignition (Diesel cycle) has a high efficiency but emits comparably more NOX and PM compared to spark ignition engines.
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Spark ignition (Otto cycle) produces less PM and NOX but has a lower efficiency due to throttling losses.
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Co-Combustion (Diesel cycle) has a high efficiency with lower emissions than an equivalent diesel only engine. The diffusion rate of H2 is comparably higher than with other gases so it mixes naturally into a homogeneous mix.
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H2 Mono-fuel (Otto cycle) can reach nearly zero-emission and the high efficiency of a diesel engine. A high lambda value for low NOx emissions is required. But larger engine size required due to reduced power output
Equipment
The equipment for the H2 storage and distribution system on board consists of:
Figure 2: Variants of hydrogen combustion engines principles
- PFI (Port Fuel Injection) - Hydrogen is injected directly behind the valve into the intake air during the intake stroke. Benefits are that backflash may be limited to one cylinder, drawbacks are that it relies on in-cylinder mixing (challenging at higher speeds) and the timing and control of the hydrogen system is more complex. Hydrogen supply pressure is typically ‘medium’.
- DI (Direct Injection) – Hydrogen is injected directly into the cylinder. Benefits are that it is not possible to get backflash, drawbacks are that in order to overcome cylinder pressure, the injection pressure must usually be much higher which can impact useful range from the hydrogen tanks. Hydrogen supply pressure is typically ‘high’.
- During the compression stroke hydrogen mixes with air in the case of PDI or DI type systems.
- A small amount of diesel pilot fuel is injected into the combustion chamber .
- Diesel auto-ignites due to the high temperature and pressure and co-combusts with all the hydrogen, forcing the piston down during the power stroke.
- The cylinder is cleaned during the exhaust stroke. Due to the hydrogen co-combustion the CO and CO2 emissions have strongly reduced in the exhaust gases.
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H2 ICE
FACT SHEET N 2
For smaller ships needing smaller quantities of H2, a fixed tank system that can be refueled with a small mobile refueling station might be a favorable option.
Special Safety & Other Requirements
The primary hazards and issues associated with hydrogen systems can be categorised and prioritised as follows:
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Flammability:
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Pressure effects
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Easy ignitability of mixtures with oxidant
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Small size of the molecule:
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Low viscosity
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High diffusion rate
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High buoyancy
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Interactions with materials (embrittlement of certain metals)
Figure 3: 500 bar H2 Tank-Tainer with 500 kg of H2
As hydrogen refuelling infrastructure in harbours is not existing, it might be favourable to use swappable hydrogen tank solution for larger volumes. Filling the MEGC with high-pressure hydrogen takes several hours, blocking the ship at the port. The regulatory aspects to enable the use of one tank-system on several ships are still being worked out. A 20 Feet Container with 500 kg of usable hydrogen with ADR/ADN-certification is on the market. Currently there are two pressure levels favoured by the industry: 350 and 500 bar.
Since hydrogen burns with a nearly invisible flame, detectors for flame monitoring are needed. For bunkering operations, it is important to use non-sparking tools.
The use of CO2 as a fire extinguishing agent is not recommended. Small particles of dry ice are formed during discharge. The rapid flow of particles can generate considerable amounts of static electricity, which can act as a source of ignition.
Tank System for Compressed Hydrogen
The tanks are typically stored on deck in a safe location; storage under deck might also be possible. From a safety point of view placing the H2 tank-system on deck is the safest solution since ventilation and dilution are the most important safety measures.
The hydrogen tank system typically consists of several individual cylinders, which are combined in a multiple element gas container (MEGC) that is connected to the ship via one fitting.
Source:
Argo-Anleg
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Asphyxiation hazard if oxygen is replaced
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Hazards associated with the storage procedure:
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Elevated storage pressure for gas
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Low temperature for cryogenic liquid
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Others for other methods, such as metal hydrides
ES-TRIN 2023 Article 30.04 states that “a risk assessment shall be conducted to ensure that risks arising from the use of fuels with a flashpoint equal to or lower than 55 °C affecting people on board including passengers, the environment, the structural strength and the integrity of the craft, are addressed.”
A HAZID study may cover the following areas (as applicable):
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General arrangement of vessels
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H2 fuel-storage arrangement and details
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H2 fuel supply and vapour-handling system, from fuel storage to machinery spaces
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H2 fuel arrangement in fuel handling room and engine room
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General arrangement of the fuel-handling and engine rooms, including their ventilation
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Main engine safety concepts and vessel integration
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Hazardous area classification plans
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Ventilation and vents for stored H2 fuel, fuel-supply system, machinery space and hydrogen consumer
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H2 fuel-bunkering arrangement
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Safety systems
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Gas detection and firefighting arrangement
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Arrangements to purge or make H2 inert
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Cargo storage and its impact
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Bunkering
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Emergency Escape and Rescue
Very good forced or natural ventilation of the areas with hydrogen is necessary. It must also be ensured that EX zones are formed around installation locations and ventilation outlets.
Crew Skills
As of today, there is no official certificate for training personnel on the hydrogen. Nonetheless, the crew must be trained and certified to be able to use the hydrogen system on bord, be familiar with the detection of leaks and the partial system shutdown procedures. Especially also for the swapping process of hydrogen tank systems on ships. Currently, the manufacturer of the hydrogen tank-system must propose a dedicated training to the crew.
However, CESNI has developed guidelines (recommendations) concerning competences required for operation of craft using methanol as a fuel and for operation of craft with an electrical power supply for propulsion. Similar recommendations are currently being developed for operation of craft using hydrogen as a fuel.
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H2 ICE
FACT SHEET N 2
Crew training procedures or H2Barge2 and Antonie were composed by the following chapters:
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Familiarity with physical and chemical properties of fuels aboard ships subject to the ESTRIN and IGF Code.
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Operate the controls of fuel related to propulsion plant and engineering systems, services and safety devices on ships subject to the ESTRIN and IGF Code.
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Plan and monitor safe bunkering, stowage and securing of the fuel on board ships subject to the ESTRIN and IGF Code.
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Take precautions to prevent pollution of the environment from the release of fuels found on ships subject to the ESTRIN and IGF Code.
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Monitor and control compliance with legislative requirements.
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Take precautions to prevent hazards.
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Apply occupational health and safety precautions and measures on board a ship subject to the ESTRIN and IGF Code.
Economics
The investment and operating costs are highly dependent on the individual ship and its operational profile. Nevertheless, there are key figures for some components. These are linked to a database so that they are updated as soon as new information is available.
Investment Costs
The investment for the hydrogen engines is between 600 € and 700 € per kW. For the H2 storage 800€/kg is a guiding value.
Operational Costs
Currently, the price for Hydrogen is between 10€ and 16€ per kg. A level to get near the diesel price would be between 4.5 €/kg and 6 €/kg.
Consideration before Deployment
Being carbon-free, makes the hydrogen operation of the combustion engine at least theoretically CO2, CO and hydrocarbon-free. In real operation, however, traces of hydrocarbons in the exhaust gas can be detected due to lubricating oil in the combustion chamber (it should be noted in that in the case of vehicles, monofuel combustion engines are classed as zero emissions). The local emission of nitrogen oxides, though, must be considered. The formation of nitrogen oxides in combustion can, for example, be greatly reduced by appropriate regulation. The remaining nitrogen oxides in the exhaust gas are then converted by a catalyst (SCR) which is a well-known technology.
H2 ICE
FACT SHEET N 2
Argo-Anleg GmbH (DE)
FPS – Future Proof Shipping (NL)
Mercurius Shipbuilding BV (NL)
ZES – Zero Emission Services (NL)
Compagnie Fluviale de Transport (FR)
Sogestran (FR)
Koedood Diesel Service BV (NL)
CMB – Revolve Technologies Ltd. (UK)
SPB – Stichting Projecten Binnenvaart (NL)
Scandinaos AB (SE)
MARIN – Maritime Research Institute Netherlands (NL)
viadonau – Österreichische Wasserstraßen-GmbH (AT)
TTS – Transport Trade Services GmbH (AT)
ZT Büro Anzböck Richard (AT)
EUFRAK – Euroconsults Berlin GmbH (DE)
CRS – Hrvatski Registar Brodova (HR)
OST – Ostschweizer Fachhochschule (CH)
Project Coordinator
DST - Development Centre for Ship Technology and Transport Systems
Partners
Disclaimer
The content of the publication herein is the sole responsibility of the publishers and it does not necessarily represent the views expressed by the European Commission or its services. While the information contained in the document is believed to be accurate, the author(s) or any other participant in the SYNERGETICS consortium make no warranty of any kind with regard to this material including, but not limited to the implied warranties of merchantability and fitness for a particular purpose. Neither the SYNERGETICS Consortium nor any of its members, their officers, employees or agents shall be responsible or liable in negligence or otherwise howsoever in respect of any inaccuracy or omission herein.
Source: cmb.tech
Source: cmb.tech
