Exploration of Complex Electrochemical and Chemo‐mechanical Behavior of Solid Oxide Fuel Cell Fueled with Pyrolysis Bio‐oil

Abstract

Direct utilization of olive mill wastewater sludge (OMWS) bio‐oil prepared via fast pyrolysis in a Direct‐Biofuel Solid Oxide Fuel Cell (DB‐SOFC) was investigated. A viable power densities (>1,000 W m−2 at 650 °C) and 6 h operation under open circuit conditions were obtained despite crude bio‐oil complex chemistry. When heated, bio‐oil decomposes yielding gases, volatiles and solid residues (biochar). At 650 °C, polarization curve and impedance spectra of SOFC fed by bio‐oil showed peculiar shapes related to complex kinetics and charge transfer mechanism within the anode. The carbon accumulation at 650 °C is managed through oxidations with oxide ions and chemical reaction with CO2 and H2O gases. Above 700 °C, performance degradation was noted related to biochar accumulation at the anode though the promotion of Boudouard reaction, the increase in O2− transfer and possible carbon electrochemical oxidations. The anode chemo‐mechanical instability was observed explaining the rise in cell ohmic resistance and performance degradation after 6 operating hours. Globally, this work demonstrates that direct fed SOFCs with OMWS bio‐oil is achievable using Ni‐SDC anode but enhancement in fuel quality and in anode catalytic activity and stability are required to improve significantly the cell performance.

Hydrothermal synthesis of zirconia doped with naturally mixed rare earths oxides and their electrochemical properties for possible applications in solid oxide fuel cells

“…A key element for SOFCs is the electrolyte which performs two primary functions: conducting oxide, ions or protons and acting as a physical block (by isolating the fuel and air) [22].…”