Performances of a micro-CHP system fed with bio-ethanol based on fluidized bed membrane reactor and PEM fuel cells

•Assessment of membrane reactor fueled by bioethanol into a micro-CHP system.•Impact of membrane reactor operating conditions on the system performances.•Thermal integration between membrane reactor and PEM fuel cells stack.•Investigation of membrane permeate side options on performances and membrane area.•Net electric efficiency above 40% with sweep gas configuration.

A micro-CHP system, rated at 5 kWel, based on membrane reactor and PEM fuel cells is simulated in the present work. Bio-ethanol is used as feedstock and converted into hydrogen inside the innovative fuel processor: a membrane-assisted fluidized-bed auto-thermal reforming reactor. The pure hydrogen separated by the Pd-based membranes inside the reactor is fed to a low-temperature PEM fuel cells stack. Heat is recovered to produce low temperature water. Two different reactor configurations are investigated: the first one adopts a sweep-gas stream, the second one a vacuum pump. Parametric analysis is performed for both cases evaluating the impact of feed composition (water-to-ethanol ratio) and operative conditions of the membrane reactor (temperature and feed/permeate pressures) on performances and design parameters. Optimal conditions are defined as a trade-off between efficiency and Pd-membranes area. For the sweep-gas layout, net electric efficiency higher than 40% can be achieved for a wide range of operative conditions, but large Pd-membranes area is required (≈0.4 m2); for the vacuum pump layout efficiency is lower (down to 39%), but Pd-membranes area is lower too (≈0.2 m2). Future work is the economic evaluation of the system for off-grid installations.