A direct carbon solid oxide fuel cell fueled with char from wheat straw

Abstract

Direct carbon solid oxide fuel cell (DC-SOFC) is a promising technology for electricity generation from biomass with high conversion efficiency and low pollution. Biochar derived from wheat straw is utilized as the fuel of a DC-SOFC, with cermet of silver and gadolinium-doped ceria as the material of both cathode and anode and yttrium stabilized zirconia as electrolyte. The output performance of a DC-SOFC operated on pure wheat straw is 197 mW cm−2 at 800°C and increases to 258 mW cm−2 when 5% of Ca, as a catalyst of the Boudouard reaction, is loaded on the wheat straw char. Higher power and fuel conversion utilization are achieved by using Ca as the Boudouard reaction catalyst. X-ray diffraction, scanning electron microscopy, energy-dispersive spectrometer, and programmed-temperature gravimetric experiment are applied to characterize the leaf char. It turns out that the wheat straw char is with porous structure and composed of C, K, Mg, Cl, Fe, and Ca elements. The effects of the Ca catalyst on the Boudouard reaction, the performance of the DC-SOFCs operated on the wheat straw char, and the economic advantages of the wheat straw char are demonstrated and analyzed in detail.