Biogas to H2 conversion with CO2 capture using chemical looping technology: Process simulation and comparison to conventional reforming processes

Abstract

H2 is a clean fuel and crucial industrial substance with rapidly increasing global demand. Although the combustion and utilization of H2 does not emit CO2, the production of H2 from fossil fuels is associated with heavy CO2 emissions. Biogas is a renewable, carbon neutral energy source that can be potentially used as a substitute for fossil fuels for H2 production. Furthermore, with CO2 capture, H2 production from biogas can become CO2 negative. However, the energy efficiency of the conversion from biogas to H2 is usually significantly lower than natural gas-based H2 production processes due to the energy consumption associated with CO2 separation. This study presents an iron-based chemical looping technology as an alternative pathway to convert biogas into H2. This chemical looping process requires neither upstream biogas compression and purification, nor downstream CO2 removal and H2 purification, hence achieving a great level of process intensification. The chemical looping process, as well as the conventional steam methane reforming and mixed reforming processes for biogas to H2 conversion, are simulated in ASPEN to compare their performance. This simulation study shows that the chemical looping process can directly use biogas with CO2 volume ratio ranging from 0 to 50% to achieve 13–14% (relative percentage) increase in cold gas efficiency and 15–20% (relative percentage) increase in effective thermal efficiency over conventional reforming processes.