Global climate change highlights a pressing need for carbon capture and sequestration (CCS). CCS technology can act as a crutch to limit anthropogenic emissions until the energy sector shifts in favor of supplying energy from low-carbon or carbon-neutral renewables. Herein, we explore CO2
gasification of biochar (Reverse Boudouard reaction), a method of carbon monoxide-rich feedstock production for solid oxide fuel cells. Through gasification, combustion of biochar is bypassed; instead, the carbonaceous fuel is converted primarily to carbon monoxide. Though considered a poison for some fuel cells, carbon monoxide is a viable feedstock component for SOFCs. Its oxidation in the fuel cell during electricity generation produces a carbon dioxide-rich exhaust stream suitable for sequestration. Theoretically, exhaust processing for CCS for this fuel cell approach will require less energy, making it a promising alternative pathway that can be integrated more seamlessly with carbon storage processes.
Studies of the Reverse Boudouard reaction have been performed on various biomass waste feedstocks (acorns, oak, walnut shell) using thermogravimetric analysis with effluent analysis by gas chromatography. Experimental mass loss data show that the reaction is favored at temperatures near 850ºC, consistent with thermodynamics and with typical operating conditions of SOFCs. The addition of an iron catalyst to the biochar markedly increases the rate of gasification. The raw biomass was found to be more reactive than its biochar counterpart.