Valorization of Oil Palm Waste into Bioenergy and Value-Added Products: A Review and Future Research Directions

The palm oil industry generates substantial amounts of lignocellulosic and liquid residues, including empty fruit bunches (EFB), palm kernel shells, mesocarp fibers, and palm oil mill effluent (POME). If not managed sustainably, these residues pose significant environmental challenges. However, they also represent a promising feedstock for renewable bioenergy and bio-based products, supporting circular economy goals and low-carbon transitions. This review systematically explores various conversion technologies applied to these residues, including thermochemical (e.g., pyrolysis, gasification), biochemical (e.g., anaerobic digestion, fermentation), and physicochemical approaches. In addition to energy generation, the potential to produce value-added products such as biochar, bioplastics, organic fertilizers, biocomposites, and liquid smoke is examined. The review also draws on the author's prior research experience, including the conversion of POME into biogas and biodiesel, as well as the utilization of EFB to produce biochar and organic fertilizer. Key technological barriers, regulatory gaps, and sustainability challenges are identified. Finally, the paper outlines future research directions, emphasizing the development of integrated biorefinery systems, process optimization, life cycle sustainability assessment, and scale-up feasibility. This review is intended to provide strategic insights for researchers, policymakers, and industry stakeholders in leveraging palm oil waste for a more sustainable bioeconomy.