Stages in the Utilization of Empty Fruit Bunches at Indonesian Palm Oil Mills

In addition to palm kernel shells (PKS) and mesocarp fiber, another solid biomass waste product available in large quantities at palm oil mills is the empty fruit bunch (EFB). EFB represents the largest volume of biomass waste generated by these mills. Mesocarp fiber, along with a portion of the palm kernel shells (PKS), is typically consumed as fuel for boilers. In fact, the volume of EFB produced exceeds that of the mill's primary product, crude palm oil (CPO). Despite this, EFB—which accounts for approximately 20% of the fresh fruit bunch (FFB) weight—remains largely unutilized. Given its substantial volume, it also poses a significant potential for environmental pollution. 

Many mills are striving to achieve a "zero waste" status, which necessitates the processing of empty fruit bunches (EFB). However, the challenges lie in determining the appropriate processing methods, the resulting products, and the overall economic viability. Ideally, this waste should not only cease to be an environmental pollutant but also generate additional profit—ideally, by produce products that maximize returns. A realistic approach, therefore, involves processing EFB in a way that prevents environmental pollution while minimizing the capital investment required for the necessary processing equipment. These factors are critical considerations, grounded in both current realities and future developments.

Empty Fruit Bunches (EFB) have significant potential for use in various bioenergy and biochar products. Through a process of biomass densification, EFB can be converted into pellets, which—much like palm kernel shells (PKS)—can be utilized within the energy sector. Given the massive volume of EFB available, the potential for EFB pellet production is substantial. EFB pellets are expected to emerge as a future trend, following in the footsteps of palm kernel shells (PKS), primarily due to their abundant availability and the fact that the vast majority remains unutilized. When compared to other potential raw materials for pellets—such as wood waste from forestry or the wood working industry—the volume of EFB is highly competitive, if not greater. Furthermore, unlike wood pellets derived from energy plantation (which require the cultivation of species such as calliandra or gliricidia), the production route for EFB pellets is significantly faster.

Another use for EFB (Empty Fruit Bunches) is the production of biochar. Biochar can serve as a soil amendment in the agricultural sector—specifically within oil palm plantations, whether company-owned or managed by smallholders. The application of biochar enhances nutrient use efficiency (NUE) by effectively turning fertilizers into slow-release products. Furthermore, biochar producers can generate revenue through carbon credits by adhering to methodologies established by recognized carbon standards, such as Puro, Verra, or Isometric. Industrial-scale slow pyrolysis equipment used for biochar production also generates excess energy—such as syngas—which can be utilized as fuel for palm oil mill boilers (via co-firing) or for other applications.

Currently, many palm oil mills utilize empty fruit bunches (EFB) by burning them in simple incinerators (as shown in the photo), which yields EFB ash—a substance rich in potassium that can be used as fertilizer. However, these simple incinerators not only generate smoke pollution but also fail to harness the heat produced during combustion. Upgrading to more efficient incineration systems—such as those employing reciprocating grate combustors—and incorporating pollution control equipment, like water scrubbers, would render the utilization of EFB environmentally friendly. Furthermore, the heat generated from combustion (waste heat recovery) can be harnessed for various purposes, including cogeneration with palm oil mill boilers, electricity generation, or other applications.