Preliminary Risk Evaluation of Methanol/Water Storage in Fuel Cell Integrated Systems for Onboard Applications

In this work, a preliminary risk evaluation of the methanol/water storage in fuel cell integrated systems is performed. The system which couples methanol steam reforming and the fuel cell to generate electricity is considered as a solution in several industrial projects for onboard applications. The challenge of such a system is to control the thermal loads to operate under fully autothermal conditions, recycling the dissipated heat from the fuel cell to preheat and evaporate the reactant mixture. To implement these systems, safety issues must be identified and minimized. Considering the autothermal operating conditions of the methanol steam reforming unit, the water/methanol ratio was set at 3. Under these conditions, the mixture is safer than pure methanol in terms of flammability and toxicity, but not yet inherently safe. Starting from the generation of a hole on the storage tank as initiating event, the consequence analysis as well as some preliminary risk considerations is performed by using empirical models. In this work, the focus was on the effects of a vapour cloud explosion and comparisons were made between a methanol-water solution, pure methanol, and gasoline, used in the conventional internal combustion engine.