High efficiency electricity and gas cogeneration through direct carbon solid oxide fuel cell with cotton stalk biochar

For the first time, biochar derived from a renewable resource, cotton stalk, is used as the feedstock of direct carbon solid oxides fuel cells (DC-SOFCs) for electricity and gas cogeneration. It turns out that the cotton stalk biochar has plenty of naturally grown K and Ca, which are active catalysts for the reverse Boudouard reaction in DC-SOFCs. This natural advantage of the cotton stalk biochar enables an extremely high power density of an anode-supported DC-SOFC at 850 degrees C, 0.9 W cm(-2), which is the highest among those of the reported DC-SOFCs. Meanwhile, high concentration of CO gas, which is an important feedstock for chemical industry, is obtained from the DC-SOFCs. The energy conversion efficiency of the electricity-gas cogeneration of DC-SOFCs reaches over 70%. A novel method, using compressed char, is proposed and carried out for continuous supply of cotton stalk char to a DC-SOFC. The present work has demonstrated the feasibility and advantages of cogenerating electricity and gas through DC-SOFCs with biochar derived from cotton stalk as the feedstock.