A review of torrefaction of oil palm solid wastes for biofuel production

Palm oil industry is recognized as one of the major agriculture contributions to the abundant production of oil palm solid wastes. These include empty fruit bunches, palm kernel shell, mesocarp fiber, oil palm frond, and oil palm trunk, which were obtained from plantation and milling activities. In terms of increasing the economic value and solving environmental problems, the use of these wastes as an alternative fuel is very important. However, the properties of oil palm solid wastes, i.e. low calorific value, high moisture content, hygroscopic nature, and high oxygen content, have limited the biomass usage as fuel. This review evaluates on the use of torrefaction technology to improve the fuel characteristics of these wastes. Several viewpoints concerning current research on the torrefaction of oil palm solid wastes, characterization of the raw material, properties and potential applications of the torrefied yield were provided. In addition, the potential development of the torrefaction process for the palm oil industry was also discussed. (C) 2017 Elsevier Ltd. All rights reserved.