H2 production from bioethanol and its use in fuel cells

Bioethanol was considered as raw material for hydrogen production by steam reforming, coupled with a proton exchange membrane fuel cell for heat and power cogeneration. Data and layout have been inspired by an existing unit, Helbio GH2 -BE- 5000, capable of delivering 5 kWelectrical + 5 kWthermal output. The water/ethanol feeding ratio and ethanol purity are pivotal parameters influencing thermodynamics and kinetics of the main reactions, catalyst deactivation by coking and the possibility to adopt less expensive routes for bioethanol purification. At first, two different bioethanol solutions, 50 vol% and 90 vol% were used for the steam reforming reaction at different temperature (300-750°C). Process simulation allowed to deepen the effect of the water/ethanol concentration on the overall efficiency of the system. An increase of water/ethanol ratio improved H2 yield at the expenses of higher heat input to the reformer. The presence of a high enthalpy exhaust steam increased the available thermal output, with consequent increase of the thermal and overall efficiency of the plant. Finally, the bioethanol purification step, energy and cost intensive, has been taken into account, searching for an optimization of the bioethanol purification strategy for the overall process intensification.