Power generation from palm kernel shell biochar in a direct carbon fuel cell

The diminishing fossil fuel reserves and energy shortage are serious challenges that have directed the search for alternative fuel sources for energy generation in the twenty-first century. Biomass-based carbon materials are alternative and renewable fuel sources used for contemporary energy conversion and present a promising solution to the above crisis. This study investigates the possibility of power generation from oil palm kernel shell (PKS) biochar through direct carbon fuel cell (DCFC) technology. The objective of the study is to investigate the potential of PKS biochar as a fuel source and consolidate information on the association between the structure of PKS biochar and its electrochemical performance in a DCFC. The effect of acid pre-treatment on the structure of biochar is also investigated. The samples are characterized on the basis of chemical composition (proximate/ultimate analysis) and DCFC performance in terms of open circuit voltage, power densities and electrochemical impedance spectroscopy. The results indicated that carbon, ash and oxygen functional groups on the carbon surface have a major impact on the fuel performance in the DCFC. At DCFC operating temperature of 850 °C, the pre-treated PKS biochar exhibits a maximum power density of 3.3 mW cm⁻² which exceeds that of untreated PKS biochar and activated carbon. Besides high carbon and reduced ash in the biochar, the results suggest that the existence of oxygen functional groups in the pre-treated PKS biochar also plays a crucial role in cell performance by providing additional active sites for electrochemical reaction.