PEM gensets using membrane reactors technologies: An economic comparison among different e-fuels

The aim of this work is to compare, from an economic viewpoint, the performance of small-scale PEM fuel cell gensets (based on 3 Nedstack™ stacks in series, representing a maximum gross power of 40kWe) that integrate a membrane reactor for three different e-fuels: methanol, ammonia, and methane. To achieve this objective, computer-aided process simulation is deployed to optimize the operational conditions (flow rate, temperature, pressure, and vacuum) and design (number of membranes) based on Aspen Plus™ software. The efficiency maximization resulted in a decreasing levelized cost of hydrogen (LCOH) from 8.29 €/kg_H2 in the methanol system to 6.12 €/kg_H2 in the ammonia system and ultimately to 5.43 €/kg_H2 in the methane system, with associated thermal efficiencies of 0.57, 0.92, and 0.77, respectively, at the fuel processor level. At the genset level, the reduction was from 1400 €/MWh in the electric methanol system to 848 €/MWh and 665 €/MWh in the electric and thermal ammonia systems, and finally to 627 €/MWh in the methane system, with corresponding electric efficiencies ranging from 25% to 38%. From an economic point of view only, methane would be the preferred fuel option while ammonia would be the best option from the efficiency point of view. The wide exploitation of these systems is still hindered by high costs compared to traditional ICE engine. A comprehensive cost analysis was performed for the full system with the objective to understand cost drivers and to guide future component development.