Utilization of Oil Palm Empty Fruit Bunch Biomass for Renewable Energy Generation in Palm Oil Mills

Abstract

Empty fruit bunches are the largest solid residue leaving a palm oil mill and the only major residue stream that mills routinely fail to use as fuel, despite operating a boiler on site. This paper examines why that gap persists and what conversion route resolves it. A structured review was conducted on peer-reviewed studies indexed in Scopus and SINTA published between 2010 and 2025, covering direct combustion, torrefaction, pelletisation, gasification, and integrated mill energy systems using empty fruit bunch feedstock. Retained studies were coded for the conversion route, the fuel property addressed, the reported performance, and the scale of demonstration. The synthesis shows that the barrier to direct combustion is intrinsic to the raw material rather than to boiler design: high moisture content, low bulk density, heterogeneous particle size, and an alkali-rich ash that promotes slagging and fouling together make untreated empty fruit bunches a poor boiler fuel. Upgrading through torrefaction, densification, or hydrothermal treatment addresses these properties directly and produces a fuel comparable in handling terms to the shell and fibre already burned, while gasification offers a route to higher conversion efficiency at greater capital and operating complexity. Mill-scale energy analysis indicates that recovering empty fruit bunch fuel alongside vented sterilization steam and engine waste heat raises surplus power substantially. The paper concludes that the choice among routes is determined by whether the mill intends to consume the fuel internally or to sell it, and that this decision should precede technology selection.