Advances in Sustainable Palm Oil Milling Technologies: Enhancing Efficiency and Environmental Performance

Abstract

This chapter conducts a thorough examination of current and emerging palm oil milling technologies, emphasizing their role in enhancing efficiency while addressing environmental concerns. Structured into four sections, it begins by evaluating traditional milling methods and equipment, considering their effectiveness and environmental impact in sterilization, threshing, digestion, and oil clarification. The subsequent section explores cutting-edge advancements, including automation and biotechnology applications for improved efficiency and resource optimization. The third section focuses on initiatives to reduce carbon emissions, highlighting technologies for enhanced energy efficiency, renewable energy integration, and improved waste management. Lastly, the chapter delves into the concept of a circular economy in the palm oil industry, emphasizing waste reduction, resource optimization, and sustainable practices throughout the palm oil production process. It discusses biomass utilization, by-product valorization, and integrated palm oil biorefineries as essential elements of circular economy approaches. This comprehensive exploration aims to familiarize readers with Elaeis guineensis and advocate for a more sustainable future in the palm oil industry, providing a thorough understanding of contemporary milling technologies and their potential to mitigate environmental impact.

1. Introduction

Palm oil, derived from the fruit of the oil palm tree, is a globally consumed and widely traded edible vegetable oil. The palm oil industry has undergone remarkable expansion, primarily driven by factors, such as the rapid growth of the global population and increased per capita consumption. Consequently, global palm oil production has experienced substantial growth, surging from 24 million tons (t) in 2000–2001 to an impressive 78 million t in 2021–2022 [1]. Projections further suggest that palm oil production is set to reach 156 million tons by 2050, underscoring its pivotal role in meeting escalating global demand.

The surge in palm oil production has solidified its position in the global oils and fats market, owing to its affordability, versatility, and unique properties. Palm oil finds applications across various industries, including food, nonfood, and bioenergy. Its exceptional heat stability renders it an ideal choice for frying applications. Its neutral flavor and diverse fat compositions have made it a preferred ingredient in packaged baked goods, snacks, and margarine. Furthermore, palm oil’s natural absence of trans-fats positions it as a healthier option for consumers. Trans fats, commonly present in partially hydrogenated vegetable oils, are frequently used in processed foods to enhance texture and shelf life. Moreover, palm oil extends its use to nonfood applications such as soaps, detergents, and cosmetics, given its ability to create a stable lather and offer moisturizing properties. In addition to this, palm oil holds promise as a renewable energy source within the bioenergy sector, where its cost-effective raw material contributes to biofuel production.

Indonesia and Malaysia emerge as key players in the global palm oil landscape, serving as primary producers with extensive oil palm plantations and well-established palm oil milling facilities. Presently, Indonesia stands as the world’s leading palm oil producer, accounting for approximately 60% of total production, followed by Malaysia at around 25% [1]. Beyond these two giants, several other nations significantly contribute to the global palm oil industry, including Thailand, Colombia, Nigeria, and Papua New Guinea.

The palm oil value chain comprises distinct segments (Figure 1), commencing with the upstream sector involving activities such as oil palm plantation, palm oil milling, and kernel crushing plants. Further down the supply chain, the midstream processing facilities include palm oil refineries. The downstream segment encompasses specialty fats, oleochemical, and biodiesel producers [2]. While the entire value chain holds relevance, this chapter’s primary focus lies on palm oil milling.

Figure 1.

Palm oil processing value chain. Created by Wai Onn Hong, 2020.

The subsequent sections of this chapter will delve into sustainable palm oil milling technologies, addressing their role in enhancing efficiency and minimizing the environmental footprint of the milling process. This exploration encompasses a comprehensive assessment of both traditional methods and equipment, an examination of the latest advancements in automation and biotechnology, initiatives aimed at reducing carbon emissions, and the incorporation of circular economy principles within the palm oil industry.

2. Palm oil milling operations

The typical palm oil milling process flow is best described through a series of activities conducted in different stations (Figure 2). It all begins with the transportation of fresh fruit bunches (FFB) from plantation sites to the palm oil mills. The milling operation includes several stages, namely reception, sterilization, threshing, digestion and pressing, clarification and purification, and kernel recovery. The primary products obtained from these processes are crude palm oil and palm kernels, while several forms of biomass are generated, including pressed mesocarp fibers, palm kernel shells, empty fruit bunches, and decanter solids. The liquid waste byproduct, called palm oil mill effluent, is a combination of various waste streams such as sterilizer condensate, heavy phase from clarification, and wastewater from wet separation. Within a palm oil mill, a power plant is also present, comprising a boiler house and an engine room that generates steam to drive steam turbines, producing power. The exhaust steam from the turbine serves to facilitate various processes within the mill.

Figure 2.

Typical palm oil milling process. Created by Wai Onn Hong, 2020.

2.1 Reception and sterilization

FFB delivered to the palm oil mill undergo inspection and grading for ripeness and quality standards before being loaded onto ramp hoppers and cages. These cages are transported into a horizontal sterilizer and subjected to steam heating at 143°C and 3 bar gauge pressure for approximately 90 minutes, in a process known as sterilization [3]. This procedure deactivates hydrolytic enzymes, eases the separation of individual fruits from bunches, and prepares the nuts for subsequent processing by reducing kernel breakage during pressing and nut cracking.

Various types of sterilizers are commonly used in palm oil mills, including horizontal batch sterilizers, vertical batch sterilizers, and continuous sterilizers. Each type has specific characteristics that influence its operation, although the fundamental principles remain consistent (Table 1). Additionally, there are other less common sterilizers such as tilting, oblique, spherical, and multidoor system horizontal kinetic sterilizers, with only minor variations from the three primary sterilizer types.

Parameter	Horizontal batch sterilizer	Vertical batch sterilizer	Continuous sterilizer
Operation mode	Batch	Batch	Continuous
Sterilization method	Steam and bunches in cages	Steam and bunches in a vessel	Steam and bunches on a conveyor
Sterilization pressure	Medium	Medium	Atmospheric pressure
Sterilization time	Moderate	Moderate	High
FFB movement	FFB cages	Conveyor system	Conveyor system
Labor requirement	Manual or automated operation	Automated operation	Automated operation
Space requirement	High	Moderate	Low
Environmental impact	Energy intensive	Energy intensive	Energy-efficient
Oil losses	Low to moderate	Moderate to high	Low to moderate

Table 1.

Contrasting horizontal batch sterilizer, vertical batch sterilizer, and continuous sterilizer.

Notably, the sterilization process results in the production of a byproduct referred to as sterilizer condensate. This condensate constitutes a blend of water and a medley of compounds liberated from the fruits during the sterilization phase. Rather than being cycled back into the production line, there is an increasing emphasis on the management and potential reutilization of this condensate. These endeavors have acquired significant relevance as palm oil mills seek to enhance their environmental performance through sustainable practices.

2.2 Threshing

There are two primary methods for feeding sterilized fruit bunches (SFB) into the thresher. The overhead hoisting crane or cage tipper is frequently used to transfer SFB from cages to the thresher in oil mills. In mills utilizing a cageless sterilization system, a scrapper conveyor is employed to consistently transport SFB to the thresher. The first method involves lifting, tipping, and rotating cages to release SFB onto an auto feeder, which then conveys them into the thresher. The latter method uses a series of chain conveyors to move SFB to the thresher continuously.

The thresher is essentially a horizontal rotating drum. SFB is loaded at one end, lifted, and repeatedly dropped as they travel through the drum, which rotates at about 22 rotations per minute. This process is designed to separate palm fruits from bunch stalks and typically incorporates a double-stage threshing approach. This approach aims to minimize unstripped bunches, ensuring the highest possible oil and kernel extraction rates. After passing through the first-stage thresher, SFB will typically undergo a second-stage threshing step to further minimize the presence of unstripped bunches. In some cases, roller crusher machines are used to loosen partially unstripped bunches after the initial stage of threshing.

Detached palm fruits pass through bar screens in the drum and are then conveyed to a digester, while the remaining bunch stalks, also known as empty fruit bunches, are used for mulching in plantations. In certain oil mills, additional processing is employed on these empty fruit bunches. They are shredded and subjected to pressing, resulting in two distinct products: empty fruit bunch liquor and empty fruit bunch fibers. The empty fruit bunch liquor can be marketed as secondary oil or technical-grade oil, while the empty fruit bunch fibers become a valuable solid fuel resource for the steam boiler. This dual utilization underscores the resource efficiency within palm oil mills.

2.3 Digestion and pressing

The digestion and pressing stations represent the core of the palm oil milling process, where palm oil is extracted from the fruits. Fruitlets, which have undergone sterilization, are conveyed to vertical cylindrical digesters where they are heated by steam and mashed by stirring arms. This process serves to loosen the mesocarp from the nuts and break open oil-bearing cells to release the crude oil. Proper digestion of the fruitlets typically requires a residence time of 30 minutes [4]. The digested mash is then fed into a continuous screw press that extracts the oil-containing liquor, leaving behind press cake, composed of pressed mesocarp fibers and nuts.

Advancements in the design of screw presses have led to the use of single or double screw pressing systems. Double screw pressing is especially effective in maximizing oil extraction while minimizing nut breakage. The capacity of screw presses has also increased, reducing the number of units required for milling operations. These screw presses now have design capacities ranging from 3 to 4 to 25–30 tonnes of FFB per hour. However, it is essential to ensure that any capacity upgrade of the screw press is accompanied by an increased digester capacity to prevent a shortened residence time in the digester, which could result in ineffective digestion of fruitlets.

2.4 Clarification and purification

The press liquor extracted during the pressing stage contains a mixture of palm oil, water, and solid or fibrous materials. This mixture is diluted with water and passed through a vibrating screen to remove coarse contaminants before being transferred to a crude oil tank, which serves as a rectangular buffer tank. Crude oil is then subjected to clarification at temperatures ranging from 90 to 95°C in a vertical settling tank or clarifier tank, where gravity separation takes place [5].

Improvements in the design of crude oil tanks have included the installation of coalescence plates, which enhance the oil separation process by reducing the droplet settling distance. With these enhancements, millers can initiate oil harvesting at this stage, as opposed to the traditional process where oil harvesting occurs at a later point. The underflow from the crude oil tank is then further clarified in another vertical settling tank.

In the vertical settling tank, oil, being the lighter phase, is skimmed from the top and subjected to a high-speed centrifugal purifier to remove any remaining impurities. Afterward, it is transferred to a vacuum dryer to reduce moisture. The final product, crude palm oil, is pumped into a storage tank before being sent to refineries for further processing.

The heavier phase or underflow from the vertical settling tank, often referred to as sludge, is discharged from the bottom and directed to a sludge tank before undergoing desanding. It then enters a centrifugal separator, such as a star-bowl centrifuge, nozzle separator, or three-phase decanter, to recover any remaining oil (Table 2). The water and fibrous debris or heavy phase generated are discharged as palm oil mill effluent.

Parameter	Star-bowl centrifuge	Nozzle separator	Three-phase decanter
Separation principle	Centrifugal force	Centrifugal force	Centrifugal force
Oil recovery	Efficient	Efficient	Efficient
Capacity and throughput	Moderate	Low to moderate	High
Cleaning requirement	Moderate	Moderate	Low
Space requirement	Moderate	Low	Moderate
Capital investment cost	Low	Moderate	High

Table 2.

Contrasting star-bowl centrifuge, nozzle separator, and three-phase decanter.

Although it is common practice to dilute the press liquor with hot water, some oil mills operate an oil recovery system without dilution. In this system, the press liquor is processed without the use of a vertical settling tank, instead relying on a specially designed two-phase decanter. This approach significantly reduces the volume of liquid by-products generated, leading to a reduced environmental impact.

2.5 Kernel recovery

The press cake, a tightly compressed mass produced during pressing, is fragmented in a cake breaker conveyor to loosen its structure and reduce its moisture content. Subsequently, it goes through a pneumatic separation process to effectively separate the nuts from the pressed mesocarp fibers.

The nuts are further polished in a polishing drum to remove and separate any remaining fibers from the nuts. This step is crucial for the efficiency of the nut-cracking process, which is essential for obtaining palm kernels and palm kernel shells. Excessive fibers attached to the nuts create a cushioning effect that hampers the cracking process.

The separation of palm kernels and palm kernel shells is achieved through a multistage winnowing system, which includes dry separation followed by clay bath, hydrocyclone wet separation, or a combination of both. Palm kernels are subsequently dried and stored, ready to be dispatched to kernel crushing plants. Palm kernel shells and pressed mesocarp fibers find utility as solid fuel feedstock for the steam boiler.

2.6 Boiler station

Palm oil mills are typically self-sufficient in energy generation due to the ample availability of biomass. The steam boiler within the boiler station is responsible for producing steam, which, in turn, drives a steam turbine to generate power and facilitates various processes such as sterilization, digestion, and clarification. Steam boiler operation can be simplified as the presence of “a hot heat-transfer surface covered with water.” This heat-transfer surface generates steam bubbles that rise through the water and enter the steam system. The steam can leave the boiler in either superheated form or in a saturated state, depends on the boiler’s specific design.

The process of steam generation has evolved from less efficient and labor-intensive small-capacity fiber tube boilers to automated water tube boilers. These advanced systems feature components like a “walking floor” boiler fuel storage system, moving grates for fuel combustion, and an ash removal system.

2.7 Engine room

The engine room serves as a station for generating electrical energy, utilizing both diesel generator sets and steam turbines to power a palm oil mill and its associated housing complex.

During the operation of a palm oil mill, steam turbines are relied upon for electricity generation. However, steam pressure fluctuations can occur, sometimes falling below the required level. In such cases, the diesel generator set is activated to reduce the load on the turbine.

Traditionally, diesel generator sets were the sole source of electricity during non-processing hours. Nevertheless, recent advancements have enabled many palm oil mills to operate their steam boilers and generate electricity even when the mill is not actively processing. This is achieved through automation in the fuel feeding system, allowing continuous fuel feed from stored reserves even during non-processing hours.

3. Progressive improvements in palm oil milling

The palm oil milling industry, deeply rooted in tradition, has undergone a remarkable transformation in recent years. This evolution has brought substantial enhancements to the traditional thermo-mechanical milling process, making it not only more efficient but also safer and environmentally sustainable. These advancements in efficiency and sustainability are the fruits of a deliberate integration of cutting-edge computational power, machine learning, automation systems, and innovative biotechnological solutions.

In the upcoming section, we will embark on a comprehensive journey to explore the multifaceted improvements that have been the driving force behind the palm oil milling industry’s progressive transition toward enhanced sustainability and resource efficiency.

3.1 The data-driven transformation of palm oil milling

In recent years, the palm oil milling industry has been quick to harness the significant surge in available computing power, which has led to substantial improvements in data analysis. This transformation has not only made the analytical process more cost-effective but also substantially more efficient. Companies operating within the industry have been swift to recognize the enormous potential of this enhanced computational capacity. By integrating data analysis and machine learning, they are initiating a profound shift in the way they conduct business, ultimately revolutionizing their approach to planning and process efficiency [6].

For instance, palm oil companies are now capable of leveraging historical production data to predict optimal processing times, enabling them to streamline their operations with pinpoint accuracy. This amalgamation of data analysis offers the potential to unlock heightened operational efficiency while concurrently reducing waste. It plays a crucial role in advancing the overall sustainability of the palm oil milling sector.

3.2 Machine learning’s role in enhancing milling efficiency

Spectral imaging, a well-proven technology recognized for its ability to evaluate the internal quality characteristics of diverse fruits, has undergone recent trials in the palm oil milling industry. This innovative application entails the use of spectral imaging to assess the quality of FFB as they are delivered to the mills. This marks a significant advancement, as it offers an essential initial evaluation of FFB quality, laying the foundation for subsequent milling processes that are not only more efficient but also more precise.

To enhance this evaluation, machine learning algorithms have been employed [7]. These advanced algorithms are designed to analyze the spectral data obtained from the FFB, enabling the accurate assessment of each fruit bunch’s quality. These insights serve as the foundation for creating intelligent systems that can autonomously categorize FFB based on their quality. The implementation of such systems is a pivotal step toward streamlining the milling operation. For instance, these intelligent systems can automatically segregate low-quality FFB, ensuring that only those meeting specified quality standards are subjected to further processing.

One of the most significant advantages of this approach is the ability to adjust sterilization parameters in response to the quality of the FFB. This adaptability ensures that each batch of FFB is subjected to precisely tailored sterilization processes, thus preventing the common issues of under steaming or over steaming. By doing so, the overall efficiency of the milling operation is substantially enhanced, leading to a reduction in process losses. This dual effect, characterized by increased efficiency and minimized wastage, represents a significant stride in the quest for more sustainable and resource-efficient palm oil milling practices.

3.3 Automation across various milling stations

Automation has permeated the sterilization process, revolutionizing the traditional manual procedures. Steam admission into pressure vessels is now contingent on properly closed doors, and these doors cannot be opened if the vessel remains pressurized. This technological advancement not only mitigates potential safety hazards but also leads to the prevention of unwarranted accidents. Furthermore, the implementation of advanced steam management system in sterilization station ensures a precise and efficient steam supply, catering to the varying quality of fresh fruit bunches, all the while preventing steam wastage and safeguarding against excessive steam extraction from the boiler.

The influence of automation reaches far beyond the sterilization phase. It has sparked pivotal transformations across various milling stations, generating notable improvements in safety, operational efficiency, and overall sustainability. One prominent transition includes the widespread replacement of capstan and bollard systems with hydraulic indexing systems. This shift not only minimizes the risk of accidents that could result from workers being wedged between fresh fruit bunch cages but also significantly reduces the industry’s dependence on manual labor.

Moreover, the transition from conventional hoisting crane systems to modern tipper systems has introduced heightened safety measures for operators. This change is particularly crucial for safeguarding the well-being of workers who might be exposed to risks caused by issues such as chain or wire sling failures, defective rings, eye bolts, and shackles, which can be prone to defects, overloading, corrosion, or excessive wear and tear. Notably, this transition has eliminated the occurrence of accidents, such as three-tonne cage failures from great heights due to system failures, which were not uncommon in the past.

In the digestion station, advanced automation systems are effectively maintaining the optimal quantity of fruitlets in the digester. This ensures that the digestion process runs with peak efficiency before the fruitlets are discharged to the screw press. The application of automation in the press station is equally noteworthy, where it plays a pivotal role in achieving the dual objectives of maximizing oil extraction and minimizing nut breakage. These automated processes not only enhance overall productivity but also contribute to the industry’s drive toward sustainability and resource optimization.

Although automation is already widely implemented in the clarification station, there is still considerable potential for further enhancement in oil skimming process, with the aim of reducing labor dependency. For example, the introduction of automated oil skimming mechanisms utilizing state-of-the-art technologies, such as time-domain reflectometry, can be explored in the vertical settling tank. By accurately pinpointing the interface between oil and sludge, this automation has the capacity to fine-tune oil skimming with exceptional precision [7]. This innovation not only serves to diminish the industry’s reliance on manual labor but also guarantees consistent optimization of the clarification processes, thereby mitigating the risks associated with under- or over-skimming in the vertical settling tank.

The adoption of automation in the kernel recovery station is another significant development. In this context, automation systems govern the heating and discharge sequences within kernel silos. This precision control ensures that kernels undergo optimal drying before they are transferred to the kernel bunker for storage. Additionally, this automation contributes to reducing the risk of fire incidents in the kernel recovery station by eliminating the possibility of overheating. These advancements in automation reflect a commitment to both operational efficiency and safety, reinforcing the palm oil milling sector’s efforts to align with sustainable and environmentally responsible practices.

3.4 Revolutionizing palm oil milling through enzymatic biotechnology

Traditionally, palm oil milling processes involved sterilization and digestion to facilitate mechanical oil extraction. However, this method has reached its limits, evident from the stagnant oil extraction rates over the years. The introduction of enzymatic biotechnology, a significant breakthrough in the palm oil industry, holds the promise of overcoming this challenge. Enzymes, with their ability to break down plant cell walls effectively, could revolutionize oil release and substantially enhance extraction efficiency.

Enzymatic processes, requiring minimal steps and reasonable investments, promise remarkable improvements to the bottom line. By effectively breaking down the cell walls of palm fruit, enzymes boost oil extraction efficiency without compromising the quality of crude palm oil. Several palm oil companies have either experimented with or fully adopted enzymatic biotechnology, resulting in a noteworthy increase in oil production [8, 9]. This breakthrough not only ensures enhanced efficiency but also markedly reduces the industry’s environmental footprint associated with land use, a pivotal stride toward sustainable practices.

4. Reducing carbon emissions in palm oil milling

The palm oil industry, frequently under the scrutiny of environmental critics, has embarked on a profound transformation aimed at achieving higher levels of sustainability. Central to this transformation is a concerted drive to reduce carbon emissions. The palm oil industry recognizes the pivotal role it plays in the broader context of environmental conservation and climate change mitigation. This recognition has catalyzed a dynamic shift toward more sustainable practices and technologies, ushering in an era, where carbon emissions are no longer an inevitable consequence of palm oil production. In their relentless pursuit of emission reduction, palm oil companies are at the forefront of pioneering groundbreaking approaches that span across the entirety of palm oil milling operations.

This section unravels the notable advancements in the industry’s quest for sustainability. In stark contrast to other oil crop processing facilities, palm oil mills stand out as pioneers of energy self-sufficiency, distancing themselves from conventional power sources, such as grid electricity and fuel oil. Moreover, this section discusses biogas utilization, showcasing the capture of methane emissions for electricity generation and its potential for wider applications, including bio-compressed natural gas. The section concludes by recognizing palm sludge oil as a biodiesel feedstock, emphasizing its environmental benefits, potential for reducing carbon emissions, and its alignment with sustainability and energy demands.

4.1 Self-sufficient energy practices in palm oil mills

In contrast to other oil crop processing facilities, palm oil mills have established themselves as environmentally conscious entities, pioneering a sustainable approach to energy generation. These mills have eschewed reliance on conventional energy sources, such as electricity from the national grid and fuel oil. Instead, they have long been on a path toward sustainability, leading the industry in achieving energy self-sufficiency by harnessing the potential of biomass resources. These resources include pressed mesocarp fibers, palm kernel shells, and empty fruit bunch fibers, which are expertly utilized in cutting-edge cogeneration facilities.

This concerted effort to tap into renewable energy sources has far-reaching implications not only for the palm oil milling sector but for the broader environmental landscape. Energy consumption in the milling process is no small matter, with estimates pegging it at around 18.7 kilowatt-hours per tonne of fresh fruit bunch processed [10]. This is a substantial energy demand, especially considering that the combined production of the world’s top two palm oil producers, Indonesia and Malaysia, amounted to approximately 287 million tonnes of fresh fruit bunches in 2022.

The significance of cogeneration systems in achieving energy self-sufficiency cannot be overstated. These systems have ushered in a new era of sustainability and environmental responsibility. By relying on their self-sufficient design, Indonesia and Malaysia have jointly achieved a momentous feat—significantly reducing carbon emissions. To put this achievement into perspective, it amounts to a remarkable 2500 thousand metric tons of carbon dioxide (CO₂) emissions saved.

Such a feat is not merely a commendable accomplishment in the field of carbon avoidance; it is also a resounding contribution to the global fight against climate change. The palm oil milling sector’s commitment to energy self-sufficiency stands as a pivotal step in preserving our environment, underscoring its significance in addressing the overarching issue of global warming. This journey toward sustainability in the palm oil industry showcases a path that others can follow, one that leads to not only operational efficiency but also environmental responsibility.

4.2 Harnessing biogas for sustainability

Palm oil mills produce large quantities of palm oil mill effluent (POME), which has long been recognized as a significant contributor to global climate change. This is because POME naturally decomposes in the absence of oxygen, producing biogas, primarily composed of methane. Methane is a potent greenhouse gas, with a global warming potential (GWP) 25 times greater than that of carbon dioxide [11]. If biogas emissions are not effectively controlled, methane is released directly into the atmosphere. However, the silver lining lies in the fact that this biogas simultaneously represents a valuable renewable energy source, offering the prospect of a sustainable solution.

Palm oil mills have embarked on a transformative journey toward achieving a net-zero carbon footprint. Central to this transition is the capture and conversion of biogas, mitigating methane emissions while concurrently generating renewable energy. This paradigm shift revolves around utilizing biogas for electricity generation, primarily through gas turbines. The electricity generated has two uses: it can power the mill, and in some situations, extra power can be sent to the national grid, benefiting nearby homes through the Feed-in-Tariff scheme. By adopting this environmentally responsible approach, palm oil mills not only prevent methane emissions into the atmosphere but also contribute to the generation of green energy.

Indeed, the potential applications of the biogas generated in palm oil mills extend beyond electricity generation. This versatile resource can be directed into multiple avenues, offering avenues for sustainability. One path involves feeding the biogas directly into the steam boiler system, where it serves as an efficient and eco-friendly fuel source. This not only reduces the mills’ reliance on fossil fuels during non-processing hours but also enhances their self-sufficiency in energy production. Furthermore, biogas can undergo an upgrading process to become bio-compressed natural gas (Bio-CNG), a clean and sustainable alternative to traditional fossil fuels. By taking this approach, palm oil mills can further reduce their environmental footprint and participate in the broader goal of transitioning to eco-friendly energy sources.

While biogas power plants are not uncommon in palm oil plantations, their full potential has not yet been realized. The primary obstacle lies in the associated costs of constructing biogas plants, substations, and high-tension lines, particularly in the rural areas, where palm oil mills are typically located. Nevertheless, the palm oil industry’s proactive stance in fully harnessing this renewable energy source will not only contribute significantly to reducing carbon emissions but also provide an affordable, reliable, sustainable, and modern energy source for rural communities. The time has come to unlock the true potential of biogas and reshape the landscape of both palm oil production and rural energy accessibility.

4.3 Palm sludge oil as a sustainable biodiesel feedstock

During the production of crude palm oil, a liquid by-product, palm oil mill effluent (POME), is generated. Instead of being left in the effluent treatment pond, palm sludge oil, a common term used to describe residual oil from POME, could become an attractive natural source for biodiesel production.

Biodiesel, produced from different triglyceride sources, is an alternative petro-diesel fuel. To date, refined palm oil has been one of the most common biodiesel feedstock type. However, the biodiesel industry has been under pressure due to rising concerns about feedstock availability and pricing. As a result, affordable and lower-quality oils like POME oil are becoming a hopeful choice for making biodiesel. This aligns with the increasing need for eco-friendly energy sources, moving away from using food-based materials for biodiesel production. Remarkably, POME oil exhibits a commendable environmental profile, boasting zero life cycle greenhouse gas emissions up to the point of its collection. The significance of this feedstock extends to the point where it qualifies for double accounting of greenhouse gas savings under the renewable energy directive, as recognized by the International Sustainability and Carbon Certification [12].

The transition to POME oil-based biodiesel not only underscores the environmental stewardship of palm oil companies but also positions them as significant contributors to global carbon reduction efforts.

5. Circular economy principles in palm oil

The palm oil industry holds the potential to not only advance technologically but also to explore innovative business models. Embracing the principles of the circular economy, which are centered on the reduction of waste and the maximization of resource efficiency in both product and process design, can offer a promising pathway. By adopting these principles, the industry can efficiently harness agricultural biomass, promote resource conservation, and unlock new avenues for business development.

In an era, where the imperative of sustainability reigns supreme, industries globally are undergoing a paradigm shift in their resource management and waste reduction practices. A frontrunner in this movement is the palm oil sector, a crucial player in the global food and bioenergy supply chain. As sustainability continues to take center stage, the integration of circular economy principles into palm oil manufacturing and waste management surfaces as a potent strategy to curtail environmental impact and fortify overall sustainability.

The concept of the circular economy model paints a vivid picture of a regenerative system, meticulously designed to maximize resource efficiency, minimize waste generation, and extend product lifecycles through thoughtful design, reuse, and recycling. This model represents a significant departure from the traditional linear approach of “take-make-dispose” and has been steadily gaining traction across various industrial domains. The impetus behind this transformation is the aspiration to disentangle economic growth from resource depletion and environmental degradation.

The palm oil industry, which has been under scrutiny for its environmental footprint, now stands at a pivotal juncture, poised for a transformation guided by the principles of the circular economy. This section extensively explores the plausible incorporation of circular economy principles across diverse domains within palm oil production, presenting avenues for enhanced resource efficiency and a substantial reduction in waste generation. In embracing these practices, the industry not only addresses its sustainability issues but also positions itself as a potential pioneer in sustainable and responsible resource stewardship.

5.1 Transforming waste into resources

The concept of circularity within the palm oil milling industry hinges on the efficient and resourceful management of valuable assets, effectively reframing waste as a valuable resource rather than a disposal concern. A standout example of this circular paradigm is the creative repurposing of organic waste, notably empty fruit bunches (EFB), which undergo transformation into natural mulch and are reintroduced into the fields. This circular system yields a plethora of benefits, encompassing its role in efficient weed control, the mitigation of soil erosion, the preservation of soil moisture, and, notably, the substantial reduction in waste disposal, marking a significant stride toward environmental responsibility.

Furthermore, POME emerges as an untapped resource reservoir. Its application in field irrigation, especially during prolonged dry spells, proves invaluable in alleviating moisture stress on oil palms. Beyond its role as an irrigation source, when POME is distributed across the fields, it acts as a supplementary nutrient source, enhancing the overall health and productivity of oil palms. This dual-pronged approach to repurposing organic waste is not merely an exercise in waste minimization; it embodies a comprehensive resource optimization strategy in line with the fundamental tenets of a circular economy.

Adding depth to this sustainable cycle, the co-composting of EFB and POME results in the creation of nutrient-rich organic fertilizer [13]. This integration of organic materials into the agricultural cycle fundamentally elevates soil fertility, ultimately cultivating the growth of robust and productive palm plantations.

5.2 Second-generation bioethanol from palm oil biomass

Another notable transformation within the palm oil industry involves the strategic utilization of palm oil biomass, encompassing various components, including oil palm trunk, oil palm fronds, empty fruit bunches, and palm kernel cake. These diverse biomass sources serve as rich reservoirs of cellulosic biomass, holding the potential for significant environmental and economic benefits. The process begins with a crucial pre-treatment step, where cellulosic biomass is broken down into pulp. After this, the cellulose and hemicellulose components, which form the structural framework of these biomaterials, are efficiently hydrolyzed into simpler sugars.

This hydrolysis process sets the stage for the subsequent step, where yeasts come into play, adeptly fermenting these simple sugars to produce second-generation bioethanol. The remarkable similarity to first-generation bioethanol production is seen in the subsequent separation of ethanol from the fermentation broth through the distillation process. However, the environmental and performance benefits of second-generation bioethanol are notably distinct. The advantages of this sustainable fuel source are multifaceted. Notably, it carries the potential to reduce greenhouse gas emissions by over 80% when compared to conventional gasoline [14], marking a significant stride in combating climate change and reducing carbon footprints. Furthermore, second-generation bioethanol boasts a higher-octane number [15], an attribute that not only aligns with environmental sustainability but also enhances engine performance. This transformative approach in the palm oil industry showcases how sustainable practices and innovation can go hand in hand, resulting in both ecological and industrial benefits.

5.3 From palm kernel cake to poultry feed

Palm kernel cake (PKC), a residual product derived from the extraction of palm kernel oil, has traditionally found use as dairy cattle feed due to its protein, fat, and energy content. However, its adoption in poultry diets has been limited, primarily because of its high fiber content. Nonetheless, a pioneering biotechnological solution offers the prospect of expanding its applications. When PKC is directed into bioethanol production, it gives rise to a valuable by-product known as distiller’s dried grains with solubles (DDGS). This nutrient-rich DDGS material is a residue resulting from the yeast fermentation process and exhibits the potential to replace traditional corn and soybean meals in broiler diets without compromising performance [16, 17].

In Indonesia and Malaysia, where broiler meat is a dietary staple, substantial quantities of soybean meal, approximately 6.7 million tonnes in 2021, are imported for the poultry industry [18]. By optimizing the use of all PKC generated in these countries, it is anticipated that this can significantly offset a substantial portion, potentially up to 70%, of imported soybean meal. Although no specific environmental study has been conducted in this regard, researchers have noted that DDGS-based diets in other industries tend to have a lower carbon footprint compared to conventional corn-soybean meal diets. The transformation of PKC into a protein-rich animal feed not only promotes the efficient utilization of agricultural biomass but also aligns with broader societal objectives related to climate mitigation and sustainability. This innovative approach not only bolsters the utilization of a valuable agricultural resource but also contributes to our collective efforts in addressing climate-related challenges.

5.4 Palm oil biomass in the bioplastic revolution

The petrochemical industry has witnessed the rapid expansion of petroleum-based plastics, making it the fastest-growing material sector over the past several decades. Notably, it is projected that plastics will contribute to 20% of total oil consumption by the year 2050 [19], underscoring the pressing need for eco-friendly alternatives to mitigate emissions.

Palm oil biomass offers a promising avenue for addressing this issue. The enzymatic hydrolysis of cellulosic biomass results in the production of simple sugars, which can serve as sustainable building blocks for various applications, including the production of bio-based monoethylene glycol (MEG). MEG, a key component in polyethylene terephthalate (PET), finds extensive use in a wide range of products, with plastic beverage bottles being one of the most common applications [20]. Although traditional sources for bio-based MEG have primarily consisted of hardwood feedstocks obtained from sawmills and by-products of the wood industry [21], evidence supports the feasibility of transitioning to palm oil biomass as a source for green chemistry [22]. This illustrates the transformative potential of palm oil biomass in revolutionizing the bioplastic market and steering it toward greater sustainability.

6. Conclusion

In conclusion, this chapter provides a comprehensive overview of the contemporary landscape of palm oil milling technologies and their pivotal role in elevating efficiency while mitigating environmental implications. The four main sections of this chapter have collectively shed light on the transformation occurring within the palm oil industry from traditional practices to cutting-edge advancements. The first section examined conventional palm oil milling techniques, evaluating their effectiveness and environmental impact. The second section delved into innovative technologies and practices, emphasizing data analysis, machine learning, automation, and biotechnology applications as drivers of efficiency and resource optimization. The third section highlighted the industry’s efforts to reduce carbon emissions through self-sufficient energy practices, biogas harnessing, and the utilization of palm sludge oil as a sustainable biodiesel feedstock. The fourth section introduced the concept of a circular economy in palm oil milling, showcasing the potential of biomass utilization, by-product valorization, and integrated palm oil biorefineries to minimize waste and optimize resources.

These insights serve to acquaint readers with the dynamic landscape of Elaeis guineensis, emphasizing a commitment to a more sustainable future within the palm oil industry. By embracing contemporary milling technologies and integrating sustainability practices, the industry can proactively address environmental concerns while maintaining efficient production. It is our hope that this chapter has not only informed but also inspired stakeholders within the palm oil sector to embark on a path toward enhanced efficiency, lower environmental impact, and a more sustainable and responsible future. As the industry continues to evolve, these advances in sustainable palm oil milling technologies will play a pivotal role in its transformation and environmental stewardship.