Thermochemical Properties of Brunei Rice Husks and Suitability for Thermal Conversion via Pyrolysis Process

Alternative energy in the form of biofuel is an attractive option for reducing the dependence of fossil fuel usage in Brunei. Thermal conversion with pyrolysis is therefore a viable process for biofuel production. Selection of biomass feedstock and their characterisation is an important pre-requisite step to find out whether the material is fit for thermal conversion into biofuels. Brunei rice husk (BRH) of the ‘Laila’ species has been characterised according to standard procedures and compared to other types of agricultural waste in order to assess their suitability for use in biofuel production. Proximate, ultimate, compositional, heating value and Thermogravimetric (TG) analyses were carried out on Brunei and African Rice Husks. Proximate analysis shows that BRH contains 8.43% moisture, 68.25% volatiles and 14.83% ash, with the ash composition analysis showing a significant amount of potassium, calcium and phosphorus thus having an effect on pyrolysis products yields. Elemental analysis shows that the nitrogen and sulphur content were low. The thermal degradation behaviour of BRH using TGA suggests a weight loss of around 70% at temperature below 600oC. Compositional analysis revealed that BRH consists of 41.52% cellulose, 14.04% hemicellulose and 33.67% lignin by weight. The characterisation methods have shown that BRH high volatile content, a heating value of 17.34 MJ/kg and low nitrogen and sulphur content makes it a suitable feedstock for thermal conversion into biofuels.