Integrated CHP with autothermal biomass gasification and SOFC–MGT

Autothermal biomass gasification produces a gaseous fuel that, after gas cleaning and conditioning, can be used in solid oxide fuel cells (SOFC). Conceptually, the integrated system can be near atmospheric or at elevated pressures, allowing combination with a micro gas turbine (MGT) expander. This work comparatively investigates three small scale combined heat and power (CHP) configurations that integrate these technologies: (a) gasification at 4 bar and MGT, (b) gasification at 1.4 bar and SOFC and (c) gasification at 4 bar and SOFC–MGT. Aspenplus™ process simulation software was used for modelling each major and peripheral component of the CHP. Interestingly, the MGT system proved more efficient than the atmospheric SOFC, both of which were surpassed by SOFC–MGT performance that reached an exergetic electrical efficiency of 35.6% using an SOFC of 100 m2 active surface area and nominal biomass throughput of 200 kg/h. An exergy analysis allowed optimisation of the SOFC fuel utilisation factor (Uf) and efficiency impact of system capacity and level of product gas moistening prior to the cell.