System-level techno-economic analysis of hydrogen-fuelled genset internal combustion engines with exhaust-driven power recovery

Hydrogen-fuelled internal combustion engines (H 2 -ICEs) are increasingly considered as transitional low-carbon power technologies, yet their deployment is limited by reduced efficiency and high electricity costs under open-cycle operation. This study presents a unified thermodynamic and techno-economic comparison of gasoline, open-cycle hydrogen, and waste-heat-recovery-integrated H 2 -ICE generator systems using an ASPEN-based process simulation framework. At the highest stable equivalence ratios examined (φ = 1.045 for gasoline and φ = 0.857 for hydrogen), the open-cycle H 2 -ICE exhibits a 17.5 % lower brake thermal efficiency than gasoline, at 33.4 % versus 40.5 %. To mitigate this penalty, an exhaust-mounted electric turbogenerator (ETG) coupled with a proton exchange membrane (PEM) electrolyser is integrated to recover exhaust energy and enable in-situ hydrogen regeneration. When system performance is evaluated based on the combined engine brake and recovered electrical output, the integrated H 2 -ICE with waste heat recovery achieves apparent extended system-level energy utilisation factors of 54.4 % using ASPEN simulations and 52.3 % based on theoretical analysis. Techno-economic analysis under defined operating conditions of 5 h day −1 and 365 days year −1 shows that open-cycle hydrogen increases the levelised cost of electricity by approximately 34 % for grey hydrogen and more than 400 % for green hydrogen relative to gasoline, whereas waste heat recovery reduces the grey hydrogen LCOE to 0.727 MYR kWh −1 . This corresponds to reductions of 39.4 % relative to open-cycle hydrogen and 18.6 % relative to gasoline. Overall, the results demonstrate that the viability of hydrogen ICEs is governed by system-level energy recovery and integration rather than standalone engine efficiency, highlighting the thermodynamic potential of waste-heat-recovery-integrated H 2 -ICEs as a transitional low-carbon stationary power concept under favourable integration and component cost assumptions.