Fuel cell electric vehicles. Investigation of the energy balance for optimal reforming process of bio-ethanol

Abstract

Hydrogen ecosystem and hydrogen economy are relevant topics for the mobility. This article summarizes the ways of production of “green” hydrogen. The hydrogen storage and transportation are discussed as well. The article presents the concept of electric vehicle with serial range extender to extend the vehicle autonomy. Fuel cell system powered by hydrogen produced through reforming of liquid fuel from renewable resources such as bioethanol is considered as a range extender module. Alkaline fuel cell and solid oxide fuel cell are investigated for the use of a variety of liquid fuels instead of traditionally used hydrogen in others types of fuel cells. This article investigates the energy balance of the different types of fuel cells, powered by bio-ethanol. Three variants for ethanol conversion are investigated: variant 1 : reforming of bio-ethanol in external reformer to hydrogen and its conversion in alkaline fuel cell, variant 2: reforming of bio-ethanol in external reformer to hydrogen and its conversion in a solid oxide fuel cell; variant 3 : direct reforming of the bio-ethanol in the solid oxide fuel cell. The chemical processes for each variant are proposed and thermodynamic energy balance is calculated. From the results is visible that the most efficient configuration is the variant 3, the direct reforming of the bio-ethanol by the solid oxide fuel cell. The variant 3 delivers 15 MJ of energy output per kilogram of bio-ethanol, used in the fuel cell.