Assessment of biochar as feedstock in a direct carbon solid oxide fuel cell, RSC Adv., 2015, 5, 73399–73409


The feasibility of employing biochar as a fuel in a direct carbon fuel cell (DCFC) or a hybrid carbon fuel cell (HCFC) is investigated in the present study, by utilizing bare biochar or biochar/carbonate mixture as feedstock, respectively. Three different types of biochars, i.e., pistachio shells (PI), pecan shells (PE) and sawdust (SD) are used as feedstock in a solid oxide fuel cell (SOFC) of a type: Biochar|Co–CeO2/YSZ/Ag|Air. All samples were characterized by means of chemical composition (ultimate/proximate analysis), thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), X–ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), to obtain a close correlation between cell performance and biochar characteristics. The electrochemical measurements reveal that the optimum performance, in terms of maximum power density (Pmax), is obtained for the PI biochar, which demonstrated a power output of 15.5 mW/cm2 at 800 oC, compared to 14 and 10 mW/cm2 for PE and SD biochars, respectively. The obtained cell performance results are interpreted on the basis of biochar physicochemical characteristics and AC impedance spectroscopy studies. The superior performance of PI biochar is attributed to a synergistic effect of several physicochemical characteristics, involving the acidity, the volatile matter, the carbon and hydrogen content as well as the population of oxygenated surface functionalities.

DOI: 10.1039/c5ra13409a


Michalis Konsolakis a, Nikolaos Kaklidis b, George E. Marnellos b c d, Dimitra Zaharaki e, Kostas Komnitsas e
a School of Production Engineering and Management, Technical University of Crete, GR-73100 Chania, Crete, Greece - b Department of Mechanical Engineering, University of Western Macedonia, GR-50100 Kozani, Greece - c Chemical Process & Energy Resources Institute, Centre for Research & Technology Hellas, Thermi, Thessaloniki, GR-57001, Greece - d Department of Environmental Engineering, University of Western Macedonia, GR- 50100 Kozani, Greece - e School of Mineral Resources Engineering, Technical University of Crete, GR-73100 Chania, Crete, Greece