Process Comparison for Biomass Combustion: In Situ Gasification‐Chemical Looping Combustion (iG‐CLC) versus Chemical Looping with Oxygen Uncoupling (CLOU)

Biomass is an interesting renewable fuel to be used in chemical looping combustion (CLC). If the CO2 generated during biomass combustion is captured, the negative‐CO2 emission concept is possible. This work evaluates the differences between biomass combustion under two CLC configurations developed for solid fuels: in situ gasification‐chemical looping combustion (iG‐CLC) and chemical looping with oxygen uncoupling (CLOU). The combustion efficiency, tar emission, and carbon capture efficiency obtained at different fuel reactor temperatures in a continuous 1.5 kWth CLC unit were compared. Higher carbon capture efficiencies were reached under the CLOU mode, with no tar emission. Although in the iG‐CLC mode tars were always present in the fuel reactor outlet gas, high carbon capture was reached by using CO2 as gasifying agent. Moreover, a simulation of the effect of the solid inventory necessary in the fuel reactor to reach certain carbon capture efficiency was performed for both processes. Lower solid inventories are needed in the CLOU configuration, but the cost for the oxygen carrier used in CLOU is higher than in iG‐CLC.