Cogeneration in Palm Oil Mills with Pyrolysis, Initial Steps in Biochar Production and Implementation

The analogy is like cofiring carried out in coal-fired power plants by mixing biomass fuels with a certain ratio as an effort to decarbonize the energy sector in power plants. While in palm oil mills, cogeneration with pyrolysis is an innovative initial step to enter the carbon negative era with the application of biochar, the main product of pyrolysis. And because all palm oil mills use biomass fuel for their mill operations, they are already based on carbon neutral fuel, unlike coal-fired power plants which are based on carbon positive fuels because they come from fossils.

Unlike cofiring which mixes coal and biomass fuels with a certain ratio and then burns them together in a furnace such as pulverized combustion, cogeneration is done by producing energy separately but the energy output is for the same use or especially the same boiler. This is done because the types of fuels may be different, such as solid fuels with liquid fuels or the technology for producing the energy is different. With this cogeneration, it means that not all energy is produced from one energy source or energy from cogeneration is a secondary energy source to meet total energy needs, and in the case of cogeneration in this palm oil mill, energy from combustion is still the primary energy.

Then why not just do full pyrolysis? It is easier, gradually for palm oil mills to adopt pyrolysis technology and its characteristics. Because (slow) pyrolysis aims to maximize solid / biochar, the by-products in the form of excess energy (syngas and biooil) as a source of boiler fuel, the calorific value is not as much as combustion which is indeed intended to maximize heat. Only about 1/3 of the excess energy contributes (cogeneration) as boiler fuel. In other words, if full pyrolysis is carried out directly, the amount of biomass as raw material for pyrolysis becomes 3 times greater or the pyrolysis unit becomes very large so that all palm oil mill biomass waste is used, and the mill cannot sell its palm kernel shells.

What are the benefits obtained by palm oil mills if they carry out cogeneration with pyrolysis for biochar production? Among the biochar products, it can save fertilizer use in oil palm plantations, overcome the problem of empty oil palm bunches (EFB) so that palm oil mills can achieve zero waste, palm kernel shells (PKS) that have been used for boiler fuel can be sold to increase income, the productivity of fresh fruit bunches (FFB) of palm oil increases, the application of biochar in palm oil plantations is also a climate solution (carbon sequestration / carbon sink) so that it can get carbon credit compensation and with good waste management, even zero waste and the application of biochar in palm oil plantations, palm oil companies will get a good image in terms of the environment and sustainability.  

Biochar For Patchouli Plantation

Indonesia is famous for producing various essential oils, including patchouli oil, clove leaf oil and so on. The main use of essential oils is mainly for food, pharmaceuticals, fragrances (perfumes). The potential of this country to develop essential oils is very large due to climate factors, land area and soil fertility. World export-import statistics data show that consumption of essential oils and their derivatives has increased by around 10% from year to year. Of the 70 types of essential oils traded on the international market, citronella oil, patchouli, vetiver, ylang-ylang, cloves, pepper, and jasmine oils are supplied from Indonesia. Indonesia is the largest country in Southeast Asia producing essential oils and is among the top 10 in the world.

Patchouli production centers in Indonesia are in Bengkulu, West Sumatra, and Nangro Aceh Darussalam. The quality of Indonesian patchouli oil is known to be the best and controls 80-90% of the world's market share or the largest supplier of patchouli oil in the world. This patchouli oil comes from the distillation of dried leaves to extract the oil which is widely used in various industrial activities. Patchouli oil is used as a fixative or binder for other fragrance ingredients in perfume and cosmetic compositions. The area of patchouli planting reaches 21,716 ha spread across 11 provinces in Indonesia, and in 2008 about 2,500 tons of patchouli oil were produced.

Patchouli plants commonly cultivated in Indonesia are Aceh patchouli because the oil content is > 2% and the oil quality is patchouli alcohol (PA) > 30% higher than Java patchouli which has an oil content of <2%. Furthermore, with Aceh patchouli, there are three varieties of patchouli plants found in Aceh, namely Tapaktuan patchouli, Lhokseumawe patchouli, Sidikalang patchouli. The PA levels of the three varieties vary, namely: Tapaktuan (28.69-35.90%), Lhokseumawe (29.11-34.46%), and Sidikalang (30.21-35.20%).

Patchouli Oil Production in Sentra Province 2015-2020**)

One of the factors that support plant growth and optimal production is the availability of sufficient nutrients in the soil. The level of nutrient availability for patchouli plants must be optimal to obtain high growth and oil content. Patchouli is known to be very greedy for nutrients, especially nitrogen (N), phosphorus (P) and potassium (K). Patchouli plants are among those that require quite a lot of nutrients, so that production continues to run optimally, fertilizer application is carried out very seriously. This is so that the level of soil fertility must be maintained optimally if we expect optimal patchouli agricultural production. Therefore, in the shifting patchouli cultivation system, there will be a very rapid decrease in land fertility which will damage the land.

Patchouli can be cultivated on dry land, thus the development of patchouli plants is very relevant to the potential of dry land which is quite extensive in Indonesia compared to rice fields. In fact, dry land is the most widely distributed sub-optimal land, which is around 122.1 million ha consisting of 108.8 million ha of acidic dry land and 13.3 million ha of dry climate dry land. The development of patchouli plants has a dual purpose, in addition to increasing farmers' income, it also increases the productivity of dry land which is widely spread in Indonesia.

To improve land quality, namely by applying biochar. The application of biochar to agricultural land functions as a soil amendment that can improve the chemical properties of the soil (pH, cation exchange capacity, total N, and available P), the physical properties of the soil (bulk density, porosity and the ability of the soil to hold water). Improvement in the quality of the chemical and physical properties of the soil has an impact on the availability of nutrients and water through the ability of biochar to retain nutrients and water. Ultimately, the addition of biochar has implications for increasing the productivity of patchouli plants. In the future, it is hoped that with the application of biochar, more suboptimal and degraded lands which can be restored and plants productivity increased.

Optimizing the use of dry land for food crop cultivation needs to begin with land rehabilitation efforts so that plants can produce optimally. Soil amendments that are cheap, readily available and can last a long time in the soil are expected to be able to trigger the rate of increase in dry land productivity. The potential for agricultural waste to be converted into soil amendments (biochar) in Indonesia is quite large. Biochar applications have been proven to improve the quality of physical and chemical properties of the soil, as well as increase water availability. Crop productivity also increases in line with the recovery of land quality.

Biochar can also be added during composting so that more nitrogen (N) content can be absorbed in the biochar. The higher the nitrogen (N), the better the compost quality will be. Total N is one of the macro elements needed by plants in large quantities, accounting for 1.5% of the dry weight of the plant. Nitrogen is useful in the formation of protein, a component of plant chlorophyll, and if morphologically N plays a role in the formation of leaves and stems of plants or the vegetative formation of plants. Phosphorus is an absolute nutrient needed by plants after nitrogen. Symptoms of phosphorus (P) nutrient deficiency are seen as the color of the plant becomes dark green or purplish green which is then followed by older leaves turning purplish. The addition of biochar and compost, in addition to increasing the productivity of patchouli leaves, can even increase the yield of patchouli oil from an average of 2% to 4% and the patchouli alcohol content of patchouli oil from an average of 32% to 40%.

Why is There No Biochar Production for The Palm Oil Industry Yet?

Even though biomass waste is abundant in the palm oil industry, both in the plantation area and in the palm oil mill area, most of the biomass waste, especially empty fruit bunches or EFB, is still not utilized or is simply piled up or thrown away. In fact, if the palm oil industry has a strong vision about maximizing profits by minimizing the occurrence of waste, especially biomass, and maximizing environmental sustainability as well as being part of the climate solution, then biomass waste, especially empty fruit bunches or EFB, is a big opportunity.  Currently, special department in the palm oil industry that specifically deal with sustainability issues are starting to be created by palm oil companies. Waste management issues including the utilization of EFB, reducing soil and water pollution due to fertilizers and increasing fertilizer efficiency are the concerns of the sustainability department. 

The empty fruit bunches or EFB can be used as fuel so that most or all of the palm kernel shells or PKS can be sold directly and even exported. Palm oil mill boiler fuel currently uses fuel in the form of palm fiber (mesocarp fiber) and some palm kernel shells / PKS, which can be replaced using empty fruit bunches (EFB) and palm fiber (mesocarp fiber) and without palm kernel shells / PKS. Palm kernel shells / PKS are a very popular biomass fuel in the global market that competes fiercely with wood pellets. By being able to sell all palm kernel shells / PKS and at the same time utilize empty fruit bunch / EFB waste, the palm oil industry will provide many economic benefits.

The use of empty fruit bunches / EFB and mesocarp fiber as a heat source for the boiler is not burned as usual or as is done by all palm oil mills today but must be gasified or pyrolyzed so that another product is produced in the form of biochar. Although gasification can be used to produce biochar, pyrolysis is more recommended because the quality and quantity of biochar will be better. The biochar can later be used for the palm oil plantation itself. The use of biochar in palm oil plantations will significantly save on fertilizer use as well as reducing water and soil pollution due to inefficient use of fertilizer. The biggest cost in operating a palm oil plantation is fertilizer, so by using biochar these operational costs can automatically be reduced. Biochar will become a slow release agent so that fertilizer use will be more efficient or increase NUE (Nutrients Use Efficiency).

Empty fruit bunches / EFB and mesocarp fiber are solid waste from palm oil mills so the waste is located around the palm oil mill, while biochar is used for palm oil plantations. In palm oil companies, management is generally separated between the plantation and mill departments. The use of biochar in palm oil plantations while the raw material comes from palm oil mills requires special arrangements regarding this matter. This could be, for example, trucks transporting fresh fruit bunch / FFB from the plantation to the palm oil mill, then after the FFB is unloaded at the mill, they then go to the plantation again carrying biochar from the palm oil mill.

Currently, no one is utilizing empty fruit bunches / EFB and palm mesocarp fiber as a source of boiler heat and biochar production. The main factor causing this is the main orientation or vision of the palm oil company itself as described above. This is predicted to change soon as awareness of climate issues increases and reaches all levels, especially in sectors related to energy and sustainibility. Moreover, when biochar is applied to plantation land, it also gets carbon credit as carbon sequestration. The smoke coming out of the boiler furnace will also be cleaner as seen from its opacity. The use of gas and liquid fuels from pyrolysis by-products will produce better combustion quality as well as smoke from the chimney. And even the liquid products from pyrolysis can also be used as biopesticides and organic fertilizers. Boiler efficiency will also increase because it uses boiler feed water (BFW) in the form of hot water from the condenser output of the pyrolysis unit.

Apart from old palm oil mills which really want to upgrade their industrial energy systems and fertilizer efficiency in their plantations including sustaibility according to this vision, new palm oil mills whose status is in the development stage should be able to apply this concept more easily. New palm oil mills can immediately follow developments and demands of the times so that they become trend setters with this vision. Being a pioneer and trend setter is indeed more difficult and even risky than just being a follower, but this will raise the reputation and become a leader in the industry so it should also have a positive impact on the company's business performance. A worthy effort.