Pelletised fuel production from palm kernel cake

Biomass is an important source of renewable energy. Worldwide, the palm oil industry generates large amounts of waste materials, such as shells, fibres and palm kernel cake, which can be used for power generation. Processing the palm kernel cake into a uniform fuel through pelletisation will be an attractive option — assessing the suitability of this process was the main objective of this research. Extensive analytical and pelletisation tests were performed to evaluate the physical properties of pellets produced from this material. The variables explored included the pelletisation pressure, temperature, fuel moisture and the effect of binders, which all had significant effects on density and tensile strength. The most favourable conditions for pellet production were a pressure of 9338 psi/64.38 MPa, a temperature of 80–100 °C and a fuel moisture content of 7.9%. These pellets had densities of 1184–1226 kg/m3 and tensile strengths of 930–1007 kPa. Adding small amounts of caustic soda (1.5–2.0wt%) to the palm kernel cake under these conditions increased the tensile strength to 3055 kPa, whereas starch additives were not found to be effective binders. It is estimated that the production of palm kernel cake pellets with 2 wt.% of the caustic soda binder would cost approximately £28–47/tonne.