Oxy-combustion of coal in liquid-antimony-anode solid oxide fuel cell system

Abstract

A novel system based on the indirect oxy-combustion of coal in a liquid Sb anode solid oxide fuel cell (SOFC) has been used to produce electricity for over 48 h. Pulverized anthracite was fed to the liquid-antimony-anode of the fuel cell, and a peak power density of 47 mW cm−2 was reached at 1023 K and 35 mW cm−2 at 973 K. The fuel cell was prepared using a porous stainless-steel tube as a support for an LSM cathode, antimony oxide (Sb2O3)/yittria stabilized zirconia (YSZ, Y0.08Z0.92O1.96) composite electrolyte (membrane), while liquid antimony acted as the anode. Liquid antimony/antimony oxide served as the intermediate medium for coal oxidation producing mainly carbon dioxide, which evolved as a separate gas stream. The fuel cell will facilitate carbon capture process, and simultaneously convert the chemical energy of coal directly to electricity. The experiment showed that while the fabricated electrolyte was porous, it became dense during the actual operation, preventing nitrogen leakage into the Sb/C side and producing reasonable open circuit voltage. Analysis of the experimental EIS data illustrates that the Ohmic resistance was the primary loss mechanism in the system. It further suggests approaches to improve the design. Continuous operation of this coal fueled oxy-combustion/fuel cell system achieved an overall efficiency of 28.2% despite of its tiny scale. Simple technologies can be employed to scale up this system at relatively low cost of fabrication and materials.