A review on production and characterization of biochars for application in direct carbon fuel cells

This review explores two areas: firstly, the production of biochars from an array of different woody and non-woody waste biomass through pyrolysis and its physical-chemical characterization. Secondly, the influence of the structural properties of biochars for application in direct carbon fuel cells (DCFCs) is also explored. The need for developing low cost and environmentally favourable carbon fuel material puts lignocellulosic biomass-derived char (biochar) into the forefront. This char fuel is produced from biomass feedstock by the process of slow pyrolysis which is regarded as the most common route of production. The degree and magnitude of decomposition of each of the biomass components is dependent on process variables such as feedstock type, reaction temperature and heating rate. The generated biochar is then utilized as a fuel in a DCFC. This review establishes an understanding of the most significant properties of the biochar fuels which include proximate analysis (information of moisture, ash, volatile and fixed carbon content), and ultimate analysis (C, H, N, S and O composition), heating values and surface area. The H/C and the O/C atomic ratios are considered as important pyrolysis indicators required for a better quality fuel.