Towards H2-free shipboard storage: Energetic and risk analysis of oxidative methanol steam reforming in integrated fuel cell systems

This work investigates the energy self-sufficiency of a methanol-based hydrogen production system through oxidative steam reforming integrated with HT-PEM fuel cells, explores process conditions for autothermal systems, and assesses accident scenarios during refueling/unloading and accidental releases. Comparisons with conventional marine gasoil highlighted differences in risk indices, pool fire zones, and toxicity. Results show that the thermal self-sufficiency can be achieved under stoichiometric conditions, but also in more water-rich conditions (water/MeOH <2, or up to 3 when Air/MeOH >0.5), eventually heat recovery from products cooling. The individual risk index is always below 10−5 years−1, the pool fire impact zone for the methanol-based system is always smaller than that of marine gasoil (up to 14 m diameter for the considered maritime case study); in contrast, the issue of toxicity is more relevant (even at distances >100 m). In the absence of the blanketing system, only partial use of the liquid is permitted under safe conditions, which in the case of pure methanol and methanol-water mixture at stoichiometric composition corresponds to 25 % of the total volume. Thanks to the effect of water, the adoption of methanol-water mixtures with H2O/MeOH = 3 is intrinsically safe.