Gas switching as a practical alternative for scaleup of chemical looping combustion

Gas-fueled chemical looping combustion (CLC) requires high-pressure operation to achieve competitive electric efficiencies. This work evaluates and compares two reactor concepts specially designed to reduce scaleup challenges under pressurized conditions: packed-bed chemical looping combustion (PBCLC) and fluidized-bed gas switching combustion (GSC). These concepts keep the oxygen carrier in a single dynamically operated reactor alternatively fed with air and fuel. Both concepts have been experimentally demonstrated and shown to achieve competitive performance in terms of electrical efficiency and CO₂ avoidance. However, the PBCLC concept holds the greatest fundamental promise due to its behavior as a plug flow reactor. Substantial further material development and testing will be required to realize this potential. The GSC concept does not face such material-related challenges, but requires reactor or plant modifications to achieve a performance that is competitive with the PBCLC concept.