The LH₂CRAFT project has completed Task 5.3, “Assessment of Main Propulsion Unit Interface,” led by the School of Naval Architecture and Marine Engineering at the National Technical University of Athens (NTUA).
The task investigated the integration of hydrogen as an onboard fuel for Internal Combustion Engines (ICEs) and Fuel Cells (FCs). Its primary objective was to identify the requirements, functionalities, upgrades and modifications needed to adapt the project’s Handling, Distribution and Monitoring Subsystem (HDMSS)—originally designed for liquid-hydrogen cargo handling—to marine fuel applications.
The assessment covered hydrogen’s chemical and physical properties, storage methods, insulation materials, sensor technologies and critical operational hazards. It also reviewed the historical development of hydrogen technologies across the transport and industrial sectors, alongside current classification society rules and IMO guidelines concerning the safety of hydrogen-fuelled vessels.
The development and application of hydrogen technologies for ICEs and fuel cells were evaluated, including the principal operational and thermodynamic challenges associated with each solution. Based on these findings, the HDMSS fuel interface was defined, establishing the auxiliary machinery, piping-network functions and system modifications required for safe hydrogen preparation and handling.
The assessment identified several important considerations for the design of marine hydrogen-fuel applications:
- Multilayer insulation, spray-on foam insulation and vacuum insulation panels are among the most prominent technologies for tank thermal insulation.
- Fibre-optic sensors offer an optimum detection solution for enclosed spaces, while thermal-conductivity sensors are suitable for oxygen-depleted supply lines and electrochemical or catalytic sensors for open-deck areas.
- Austenitic steel alloys should be used to withstand cryogenic-hydrogen embrittlement and material degradation.
- The Interim Guidelines for the Safety of Ships Using Hydrogen as Fuel constitute the most up-to-date regulatory framework, addressing fuel bunkering, preparation, storage and handling, as well as fire protection, electrical integration, ventilation and control.
- High-Pressure Direct Injection ICE configurations using pilot-fuel ignition were identified as the most suitable option for heavy-duty marine applications in terms of power density and thermal efficiency.
- Proton-Exchange Membrane Fuel Cells and Solid Oxide Fuel Cells were identified as the most appropriate electrochemical technologies for shipboard integration.
Building on these findings, Task 5.3 also proposed a systematic design methodology to support the conceptual engineering of an integrated, compliant and gas-safe HDMSS for marine hydrogen-fuel applications.
