Internal Reforming Methanol Fuel Cell Development

Abstract

Methanol is a liquid fuel which could also be produced from renewable energy sources and has appreciably high energy density. It has a high H : C ratio of 4 : 1 without any C-C bond. It is easier to reform when compared to CH 4 to produce H 2 rich gas that could be fed into a high temperature polymer electrolyte membrane fuel cell or HT-PEMFC. A typical IRMFC module consists of a HT-PEMFC thermally integrated with a methanol evaporator and reformer in a closed thermal loop. Simulations show that the total heat demand of the evaporator and the methanol steam reformer would require only 20% of the heat generated by the HT-PEMFC where the geometrical area of the HT-PEMFC is almost equal to that of the geometrical area of the reforming catalyst. In the current work a novel IRMFC which is operated in the 210-220°C range is presented. Operating an IRMFC at these high temperatures would mean novel materials and components to be employed within the HT-PEMFC as well as within the methanol reformer unit. The high temperature stable membrane electrode assemblies were developed by Advent technologies in Greece. The high temperature stable bipolar plates were developed by ZBT in Germany within the scope of a current EU funded project. When operated at 220°C on 350 mA/cm² of load current, the novel HT-PEMFC could deliver 210 mW/cm² at 0.6 V. As for the methanol reforming unit operated at 220°C, when fed with methanol-water mixture with a steam to carbon ratio of 1.5, the methanol conversion rate was around 90%. The performance analyses of the IRMFC single unit as well as that of the 5 cell unit demonstrate the potential to developing a compact light weight power generating unit offering double the gravimetric and volumetric energy densities offered by the current direct methanol fuel cell based units.