Liquid Smoke-Based Biostimulant (Foliar Fertilizer) for Application to Palm Oil Plantations Using Drones

In palm oil plantations, fertilizer is the highest cost component of their operations. Therefore, various efforts are made to optimize fertilization to ensure its maximum efficiency, including the use of slow-release fertilizers. For more details, read here. To maximize fertilization and maximize fresh fruit bunch (FFB) yields, the use of foliar fertilizers is also worth considering. Liquid smoke (pyroligneous acid) is one such foliar fertilizer, although a more accurate term is biostimulant (booster).

This is because liquid smoke does not provide nutrients such as nitrogen (N), phosphorus (P), and potassium (K). However, liquid smoke acts as a biostimulant, plant growth regulator (PGR), and natural protectant, promoting optimal leaf growth. Optimal leaf growth exponentially increases the growth of all plant organs, including stems, roots, flowers, fruit, and so on. Leaves are the primary "kitchen" of a plant, so leaf health determines the health of the entire plant system. Optimal leaf growth also increases the efficiency of fertilizer absorption (a "pump engine" effect) in the soil.

Furthermore, liquid smoke is not only used as "leaf fertilizer", it turns out that liquid smoke also functions as an organic pesticide (fungicide/insecticide). This repels pests (such as ticks and flies), and prevents leaf diseases. The phenol and acetic acid content is toxic to insects (aphids, thrips, caterpillars) and is effective in suppressing fungi that cause plant diseases. And the distinctive smell of smoke makes insects reluctant to approach and lay their eggs on the surface of the leaves. In addition, its binding properties make it difficult for pathogenic fungal spores to attach and develop on the surface of the leaves

Regarding this dual function, the use of liquid smoke for application to leaves (foliar) can be prioritized, whether it is more specifically used as a "foliar fertilizer" or as a biopesticide. This requires a number of adjustments such as dosage, additional formulations and application time. To maximize the function of liquid smoke as a leaf fertilizer, you must mix it with additional nutrients (such as liquid organic fertilizer / LOF) and apply it when the leaf stomata are fully open. Liquid smoke is able to reduce water molecules. When diluted or mixed with Liquid Organic Fertilizer (LOF), the nutritional content of the fertilizer becomes easier to enter and be absorbed through the stomata (leaf mouth). Meanwhile, to maximize its function as a biopesticide, liquid smoke needs to be combined with other vegetable pesticides. The frequency of spraying for prevention is once a week, while pest attacks are high, namely 2-3 times a week until the pest population is under control.

The use of drones for spraying pesticides and liquid fertilizer has been widely used on various agricultural crops such as rice, corn, sugar cane and palm oil. More specifically in palm oil plantations, drone applications are a modern solution for spraying fertilizers and pesticides. And in Indonesia more than 80% of drone applications are for the forestry and agricultural sectors. Efficiency factors (time, energy, operational costs, fertilizers, pesticides) and precision are the main driving forces for this drone application. This means that drone technology is expected to be an effective solution in controlling pests and diseases, fertilizing and cultivating palm oil plants. Drones are effective in increasing plantation efficiency, especially in areas that are difficult to reach. As a technology, various improvements have been made to improve its functions such as carrying capacity, spray speed, safety features and work efficiency. The use of drones supports precision agriculture and global food security with an environmentally friendly technological approach.

Spraying liquid fertilizer on the underside of leaves (underside spraying) using a drone requires special techniques. This is because drone propellers naturally produce strong downwash. This downwash effect is used to gently move and turn the leaves, so that the droplets can hit the bottom of the leaves. This is because on the bottom of the leaf, where the stomata are located the most are gathered around 80%. The spray texture is also made into mist mode (the finest dew) so that the liquid sticks evenly and doesn't drip onto the ground. Next, the drone's height, speed and nozzle angle need to be adjusted in such a way to achieve this goal. Environmental factors in the form of strong winds need to be avoided so it is necessary to adjust the right time and conditions.

As the use of biochar grows as a solution for health and soil fertility as well as a climate solution, this should also be the case with the application of liquid smoke. Liquid smoke as a by-product in the form of a liquid product from biochar production will increase along with increasing biochar production. Liquid smoke as a product produced from biomass raw materials through a pyrolysis process also encourages the use of natural materials based on renewable resources so that it is environmentally friendly and sustainable. 

Electricity Production from Pyrolysis, Using a Gas Engine or ORC Generator?

The more efficient the equipment, the greater the benefits or profits that can be obtained. This includes equipment for biochar production, namely pyrolysis. The more efficient the pyrolysis equipment, the cheaper it will be to produce biochar but also produce development products. An example is the use of byproducts from the pyrolysis process such as syngas, biooil, pyroligneous acid and excess heat. Harvesting or utilizing energy from waste heat sources that would normally be wasted is also part of efficiency as well. A number of products that can be used for energy production can be used for electricity production, namely syngas, biooil and excess heat. But there are a number of technologies for producing electricity, so which one do you choose?

A. Gas Engine

Gas engines such as the GE Jenbacher are commonly used to produce electricity from biogas. Biogas, which is a product of bioprocess, has a very dominant methane gas content, while syngas from pyrolysis, which is a thermal process, contains only a small amount of methane and more hydrogen (H2) and carbon monoxide (CO), this means that gas engines are not suitable for producing electricity from syngas pyrolysis. Apart from being suitable for biogas, gas engines such as the GE Jenbacher are also suitable for natural gas, which also contains methane gas.

B. ORC (Organic Rankine Cycle)

The main difference between the Organic Rankine Cycle (ORC) and the ordinary Rankine cycle lies in the working fluid and the temperature of the heat source used. ORC was specifically designed as a modification of the conventional Rankine cycle. The difference with the ordinary Rankine Cycle which uses steam from the boiler as the working fluid which is widely used in large capacity coal powerplants, the ORC uses a working fluid in the form of an organic fluid which has a low boiling point such as hydrocarbons or refrigerants. This low boiling point means that you can use a heat source whose temperature is not too high, such as waste heat or residual heat and so on.

And because there are many organic fluids available, selecting organic materials as suitable working fluids for ORC is no less important. In fact, the choice of working fluid for the ORC generator is very crucial because it affects thermodynamic efficiency, operational costs and safety aspects. The main factors considered are the thermophysical properties of the fluid, compatibility with the heat source, environmental impact, and commercial availability (economic aspects). So the selection of ORC fluid must balance energy efficiency, safety, environmental impact and cost.

Waste heat from pyrolysis can be recovered and used for electricity production with this ORC. Likewise, pyrolysis byproducts that can be used as energy sources are excess syngas and bio-oil. The excess syngas and bio-oil are used as fuel and the heat is used as an energy source for the ORC generator. Basically, the selection of an ORC power plant is based on electricity needs and available energy sources. 

For small electricity needs, namely in the range of 0.5 MW - 10 MW and low temperature energy sources, namely those whose temperature is below 350 C (low to medium temperature range (80 C - 350 C)), then the choice of ORC is suitable. As a comparison, steam turbines require temperatures well above 400 C and a power output of 10 MW to above 1,000 MW (as in coal-fired power plants or nuclear power plants). But why do almost all palm oil mills (CPO / crude palm oil mills), even though their electrical power production is small or an average of less than 5 MW, still use steam turbines? For an explanation, read here.

The application of an Organic Rankine Cycle (ORC) generator as waste heat to power (WHP) from the pyrolysis process is a very effective combination to increase the total energy efficiency of the system (co-generation). And modern pyrolysis units are widely used in continuous system biomass pyrolysis, namely for biochar production, which work autothermally or self-sustainably, so it is possible that the pyrolysis unit can also operate independently from the electricity generator from the ORC. This means it will reduce operational costs, because the electricity to run electric motors, pumps and so on comes from its own production. In other words, the pyrolysis unit operates independently without depending on the electricity network or PLN (Indonesia state owned company). From a climate perspective, these conditions are ideal, because the energy source comes from renewable sources (carbon neutral) and if biochar is used for carbon sequestration it means it is carbon negative. Optimizing the system so that it produces an optimal and profitable configuration is the task of engineers.

An American company, namely Quonset Soil Solutions, LLC in Rhode Island, has recently successfully installed an ORC unit to harvest waste heat from their pyrolysis unit with a capacity of 1.8 MW. Apart from that, several pyrolysis units in Europe are also reported to be using ORC with a smaller capacity. These successes will inspire and the installation of ORC units as part of biochar production with (slow) pyrolysis will continue to grow.

Conclusion:
-The ORC system is highly recommended for continuous scale pyrolysis plants (not small batch types) because it is able to convert heat pollution (waste heat) into valuable electrical energy assets constantly. ORC operations are environmentally friendly and support decarbonization targets.

-The ORC generator from waste heat pyrolysis is an efficient, safe and sustainable solution for generating electricity from waste heat energy (residual heat). This technology is also ideal for various industries that produce intermediate heat, so that energy is not wasted.

Not Only Reduce Steam Cost, but Also Reduce Water Treatment Cost for Boiler Feed Water and Even Also Increase Revenue with EFB Cogeneration

Even though biomass waste is abundant in palm oil mills, the use of efficient boilers is also needed. Efficient use of biomass waste according to the type/specifications will also provide additional benefits for palm oil mills. The longer the biomass waste, the more diverse its uses, ideally even zero waste. Apart from mesocarp fiber which is usually used 100% and added with a number of palm kernel shells (PKS) and sometimes also a few empty palm fruit bunches (EFB), an efficient boiler will optimize the type and amount of biomass. For example, PKS as a commodity that can be sold are used as little as possible for boiler fuel, so that more can be sold which increases the profits of the palm oil mill.

Photo taken from here

Is a utility business like buying steam from another company needed? Utility businesses like selling steam, heat, or electricity are indeed starting to emerge; for more details, read here. Certain companies are greatly helped and receive utility products according to their wishes. They do not want the hassle of operating a boiler, including sourcing its fuel. However, for palm oil mills that in their operations produce a lot of biomass waste that can be used as fuel, it is more practical and efficient to operate their own boiler. And this has been a common practice in palm oil mills for a long time. Therefore, cooperating with a utility company to obtain steam and electricity is not an effective solution. The effective solution is the use of an efficient boiler as explained above.

Apart from that, regarding boiler feed water to increase efficiency or reduce costs and be environmentally friendly, AOP (Advanced Oxidation Process) technology, namely an electrochemical device, is used. With this method, apart from not using chemicals so it is environmentally friendly, it will also increase the service life of the RO (reverse osmosis) membrane which is the heart of the water treatment unit. Not only will the RO membrane have a longer service life, but also the activated carbon filter and ion exchange resin, which are stages of water treatment. Apart from being environmentally friendly, this technology is also more in line with the sustainability mission.

And regarding boiler operations, even to increase the volume of PKS that can be sold, cogeneration of empty palm fruit bunches (EFB) can be carried out. In this way, the EFB, which have been waste biomass which pollutes the environment and which most palm oil mills have not yet processed, are then burned to produce heat and potassium ash. The potassium content above 30% in the ash will make quality fertilizer that can be sold or used in your own plantation. Meanwhile, the heat from burning EFB is used as additional energy for the boiler (cogeneration). In this way, 100% of PKS can be sold and even exported.

If the use of PKS for boiler fuel reaches 50% then using this technology means that 50% of the  PKS can be recovered or taken back or 100% of the PKS can be sold or even exported. For example, a palm oil mill under normal conditions can sell 2,000 tons of PKS/month, then by using this technology the palm oil mill can sell 4,000 tons of PKS/month. Of course the increase in PKS supply volume is very significant to increase income, for more details read here. 

PKS (Palm Kernel Shell) Export Business and New Varieties of Superior Palm Oil Seeds

PKS loading for export

The demand for biomass fuels as renewable energy, including PKS (palm kernel shells), is growing in line with the global decarbonization trend. Likewise, the use of biofuels such as biodiesel is also increasing. Biomass fuels like PKS and biofuels like biodiesel are both carbon-neutral bioenergy products. Both can be produced from palm oil trees. Biofuels like biodiesel are primarily used in the transportation sector, while biomass fuels like PKS are used for power generation or industrial boiler fuel. Palm oil produces its primary product namely crude palm oil and crude palm kernel oil (CPO and CPKO), while the PKS are byproducts or waste, such as EFB (empty fruit bunches) and mesocarp fiber.

Over time, the demand for palm oil has also increased, commensurate with population growth, and its use in the energy sector (biofuel) is even greater than in the food sector. To stabilize prices and avoid sharp fluctuations in palm oil prices, the Indonesian government launched the B-50 program, which uses 50% biodiesel from palm oil and 50% diesel from petroleum. With the B-50 program, palm oil demand has increased by approximately 20% over current average production.

This necessitates increasing palm oil productivity. One such effort is the use of superior seeds. By maximizing CPO production from mesocarp fiber, these superior seeds have thick fiber, thin shells (even shellless), and small kernels. The Psifera variety, with its various unique names by seed producers, is an option for this purpose. These superior seeds are even certified to assure consumers of their quality.

The initially thick PKS of the dura variety, which are favored and most sought after by PKS exporters for use in power plants, will gradually decline. However, considering the slow pace of replanting programs and minimal extensification efforts, the transition from dura to psifera PKS will be lengthy. PKS exporters can still safely export thick dura PKS. The less thin tenera PKS, as a transition to psifera, will likely become more common.

If very thin psifera PKS become commonplace, their calorific value will be low and they will be less desirable for energy applications. If this occurs, special treatment is required to make the psifera PKS more technically and economically viable for energy use. This can be achieved through compaction/densification or processing through torrefaction or pyrolysis to produce higher fixed carbon and calorific value. Furthermore, they can be compacted/densified into pellets or briquettes. 

Biochar Needs for the Iron and Steel Industry

As awareness of climate change and global warming grows, along with the Paris Agreement and Net Zero Emissions (NZE) 2050 targets for decarbonization, the use of biomass to produce biocarbon products is increasing. The iron and steel industry, in particular, faces significant demand, while supply remains limited. This has prompted several large companies to invest in large-scale biocarbon production, particularly biochar/biocoke.

Such large-scale production naturally requires abundant biomass feedstock. Specifically, in Indonesia, biocoke/biochar production from palm kernel shells (PKS) reportedly began last year. PKS was chosen because it is a readily available biomass waste product from palm oil mills. PKS and palm oil mill production in Indonesia is estimated to be around 12.5 million tons/year, but because some of the PKS is used as boiler fuel, the estimated usable PKS or remaining boiler fuel is around 6.25 million tons/year. To increase the supply of PKS from palm oil mills, cogeneration of empty fruit bunches (EFB) can be used. For more details, read here.

In addition to the PKS, biocoke/biochar and even black pellets (torrified pellets) are also produced using wood from energy plantations. Energy plantations with short-rotating crops like calliandra and gliricidia have great potential to produce this wood. Currently, wood pellets (white pellets) are being produced from these wood plantations. For more details on whether wood from energy plantations is better for wood pellets (white pellets) or biocoke/biochar/charcoal, read here.

Biocoke, biochar, and charcoal are used in the iron and steel industry as a substitute for coal-based coke in blast furnaces, while wood pellets (white pellets) and torrified pellets (black pellets) are used in power plants using both cofiring and fulfiring. In addition to their higher calorific value (around 20% higher than wood pellets (white pellets)), torrefied pellets (black pellets) are also hydrophobic, allowing them to be stored outdoors, like coal.

In today's era, the use of biocoke / biochar / charcoal to replace coal coke in blast furnaces is becoming important. Biocoke / biochar / charcoal derived from biomass is a renewable material that is sustainable as a reducing agent or fuel in blast furnaces. The chemical reaction will separate oxygen atoms from iron atoms and this will emit CO2. This will convert iron ore (Fe2O3) into crude (pig) iron.

However, the difference lies in the fact that the carbon source used as a reducing agent or fuel in a blast furnace comes from renewable and sustainable sources, making it a carbon-neutral process. Conversely, using coke from coal, as it comes from a fossil source, makes it a carbon-positive process. Similarly, using natural gas, a fossil fuel, as a carbon source for the reducing agent or fuel in a blast furnace, despite its lower carbon intensity, is considered less carbon intensive. 

The Role of Biochar in Increasing Palm Oil Productivity, Among the Use of Superior Seeds and Replanting

Palm oil productivity continues to be pushed to its most optimal point. This is because it is to meet the increasing needs, especially the mandatory B-50 biodiesel program. Of course, efforts to optimize productivity are not easy and instant. Although the key points for its realization have also been mapped, namely by replanting old palm oils, using superior seeds and intensification, the practice also requires the right method or approach and takes time. Replanting old palm oils is still very slow and has many obstacles, while the use of superior seeds has received more attention and continues to be encouraged. The analogy of using superior seeds is like comparing local cattle and superior breeds. So no matter how well the Javanese cow is cared for, its weight will not match that of the Limousin cow. Likewise with palm oil seeds.

Land intensification efforts through optimizing inputs, technology and modern cultivation methods also still need to be developed. Meanwhile, extensification or land expansion should be avoided or slowed down as much as possible, for more details, read here. Biochar can have an important role in this area of ​​intensification. Apart from the application of biochar it will improve soil health, which is an important prerequisite for plants to be able to produce optimally, it is also very environmentally friendly because the raw material for biochar is from renewable sources, namely biomass and increases fertilization efficiency (NUE = Nutrient Use Efficiency). And even the application of biochar is also a climate solution, namely as carbon sequestration. Optimizing productivity can be done by applying biochar plus using superior seeds using modern and environmentally friendly agricultural methods. So basically optimization is a comprehensive and measurable effort.

Indonesia contributes 25% to the world's vegetable oil supply, making it a key actor in the stability of the world's vegetable oil supply. With this position, any changes in production, export policies and Indonesia's domestic dynamics will directly impact prices and international market balance. Indonesia is currently the largest or number one producer of palm oil in the world, but it is not the best or most productive because its productivity is not yet optimal. Compared to neighboring countries, namely Malaysia, it is still inferior and slightly superior to Thailand, even though geographical factors, namely the climate in Indonesia, are much more supportive. Currently, Indonesia's CPO productivity is around 3.3 tons/hectare, while Malaysia's is around 3.8 tons/hectare, while Thailand's is around 3 tons/hectare.

Yield gap, namely the difference or gap between actual production and maximum production potential, is sometimes quite large. Several main factors that trigger yield gaps include non-optimal environmental factors such as drought conditions, to errors in cultivation practices such as errors in land clearing and planting, as well as inaccuracies in diagnosis and fertilizer recommendations. This yield gap must be minimized so that palm oil productivity can be maximized.

Sometimes the role of biochar cannot be found or seen directly in various efforts to increase palm oil productivity, but the application of biochar is very much in line with this goal. For example, the success of an palm oil replanting program depends, among other things, on the quality of seeds, fertilization, plant population and soil health. Soil health and fertilization factors can be closely related to biochar. And related to biofungicides to treat ganoderma fungus disorders, biochar can be used as a carrier formulated with other elements such as humus, amino acids, humates, hormones and so on. And because the only effective way to control the ganoderma fungus is to introduce its natural enemies in the form of biofungicides based on Trichoderma spp and arbuscular mycorrhizal fungi into the soil. However, there are still many parties who do not have adequate knowledge regarding the application of biochar.

Apart from boosting production, implementing best management practices is also important to meet sustainability standards amidst increasing pressure from environmental issues. And the application of biochar is very much in line with that point. In fact, regarding low carbon palm oil technology in the application of biochar, it is very relevant to the CECC (Controlled Emission Composting Chamber) and for more details on the application of biochar for composting, read here. Meanwhile, the trend of fertilization in palm oil plantations with the application of slow release fertilizer is also very relevant to biochar, for more details, read here. 

Indonesia's 2026 Palm Oil Replanting Target and Solutions for Utilizing Palm Oil Trunk Waste

Indonesia's stagnant national palm oil productivity requires an immediate solution. If this situation is not addressed promptly, Indonesian palm oil productivity will decline in the future. This is undesirable given the increasing demand for palm oil as a vegetable oil, including its use in biofuel, namely biodiesel. The launch of the B50 biodiesel program demands increased palm oil productivity. However, the question remains: why palm oil? Aren't there other crops that can produce oil with a comparable yield for biodiesel production? Nyamplung is a strong candidate for this; read more details here.

In palm oil, productivity can be increased through the use of superior seeds, replanting, and land intensification. In terms of land area, replanting palm oil plantations, with an ideal target of 5% per year, is very significant. With Indonesia's current 16.8 million hectares of oil palm plantations, that translates to 0.84 million hectares per year. Besides the high costs, the resulting biomass waste, or palm oil trunks, is also substantial. This clearly holds potential for an environmentally friendly bioeconomy-based industry, or circular economy.

With an area of Indonesia's palm oil plantations of around 16.8 million hectares, 9 million hectares are managed by private companies, 550 thousand hectares are owned by state-owned companies (PTPN), 6.1 million hectares belong to people's plantations or small farmers and the rest have not been verified. And based on data from the Central Statistics Agency (2024), recorded 10 provinces in Indonesia with the largest oil palm plantations in sequence, namely Riau province with 3.49 million ha, Central Kalimantan province with 2.03 million ha, North Sumatra province with 2.01 million ha, West Kalimantan province with 1.82 million ha, South Sumatra province with 1.40 million ha, East Kalimantan province with 1.32 million ha, Jambi province with 1.19 million ha, South Kalimantan province with 497.2 thousand ha, Aceh province with 487.5 thousand ha, and West Sumatra province with 379.6 thousand ha. And a total of 26 provinces in Indonesia as centers of palm oil plantations.

The palm oil industry, as one of the national strategic industries, receives significant government support, including the People's Palm Oil Replanting (PSR), which remains a national strategic program, although its realization has not yet reached the target. South Sumatra, as one of the national palm oil plantation centers, also recorded the highest PSR realization. PSR realization in 2025 is approximately 40,000 hectares, or 33% (one-third) of the target of 120,000 ha. This represents a slight increase compared to 2024, which was only 31% of that year's target. Specifically, South Sumatra has replanted approximately 75,000 ha of smallholder palm oil plantations from 2017 to 2025.

The government is targeting a national PSR of 50,000 ha for 2026, a much more realistic figure than in previous years, with South Sumatra province targeting 5,750 ha. However, given Indonesia's oil palm plantation area, the 2024 and 2025 targets of 120,000 ha are very low, especially for 2026, which is only 50,000 ha. Under these conditions, efforts that can be accelerated to increase national palm oil productivity are through the use of superior seeds and land intensification.

Furthermore, ganoderma can lead to the death of palm oil trees. Ganoderma, caused by the fungus Ganoderma boninense, attacks the palm oil's root system, disrupting nutrient and water transport. The process is very slow and is only detected when the infection is severe, resulting in yellowing leaves, drooping crowns, and even plant death. Waste from ganoderma-infected trunks must be removed or destroyed from the plantation to prevent further spread. Like waste from palm oil trunks from replanting, this waste must also be properly managed.

The issue of biomass waste from palm oil trees, which covers thousands of hectares, also presents a challenge. With such a large volume of old palm oil trees, utilizing them to create value-added products is crucial. With such a large volume, biomass processing plants or industries can be established and operate optimally, without worrying about raw material shortages. Products such as pellets, briquettes, and biochar are made from this waste biomass from old palm oil trunks. Old, dead palm oil trunks, often left unattended on land, should be utilized to create these useful, value-added products.

As shown in the diagram above, the potential for utilizing biomass waste, particularly oil palm trunks, is enormous. In the future, industrializing bioeconomics into various products is highly feasible. Palm oil trunk waste should not only pollute the environment and increase costs for palm oil farmers, but instead, it should become a profitable industrial raw material.