Compaction of palm kernel shell biochars for application as solid fuel

Palm oil is the most widely sold oil across the globe. The production of palm oil results in vast amounts of biomass waste. The palm kernel shells (PKS) can be used for energy production through gasification or combined heat and power (CHP). After gasification, some PKS remains as charred residue. In this manuscript, briquettes/pellets are produced from these biochars. The palm kernel shell biochars (PKSB) show very high calorific value exceeding typical values for biomass. The effects of water content, compaction pressure, feed particle size, compaction retention time, and the use of starch as a binder have been studied. The tensile crushing strength, impact resistance, and water resistance (immersion tests) show that the starch binder is imperative for suitable briquette quality. The use of starch increases the tensile crushing strength from less than 40 kN m−2 to more than 800 kN m−2 in the weakest (longitudinal) orientation. The tensile crushing strength of the starch-bound briquettes increases as their water content evaporates during storage and curing. It is speculated that the evaporation of water from the starch-bound sample allows for better cementing of the starch and PKSB particles.