An overview of OPS from oil palm industry as feedstock for bio-oil production

Oil palm industry generates different types of waste biomass in the form of oil palm empty fruit bunch (OPEFB), oil palm mesocarp fibers (OPMF), oil palm fronds (OPF), oil palm trunks (OPT), oil palm bark (OPB), oil palm leaves (OPL), and oil palm shell (OPS). These biomass wastes possess a great energy potential to be converted into biofuels, particularly bio-oil. Among all, the OPS have favorable physicochemical characteristics to be converted into bio-oil. Therefore, this paper mainly focuses to review the suitability of OPS as feedstock for bio-oil production compared to other oil palm biomasses. The physicochemical characteristics of the OPS, in terms of heating value, ultimate analysis, proximate analysis, and lignocellulosic composition, are presented and compared to those of the OPEFB, OPMF, OPF, OPT, OPB, and OPL. To illustrate further and signify the stability, the abovementioned properties of OPS bio-oil are also reviewed and compared to those of bio-oils produced from OPEFB, OPF, OPB, OPL, and petroleum fuels. The challenges and future prospects of OPS as a source of bio-oil are addressed and compared with other wastes of oil palm industry. Additionally, methods used for bio-oil production from oil palm industry biomass are discussed and illustrated in detail.