Drying Palm Kernel Shells (PKS) by Utilizing Waste Heat from Palm Oil Mills and POME Biogas Units

The need for palm kernel shells or PKS is getting bigger because its use is increasing and diversifying. PKS can be used as boiler fuel in industry and in power plants. In addition, it can also be used as a raw material for activated carbon whose needs are also increasing, for more details, read here. The global trend to decarbonize or replace fossil fuels with renewable energy including biomass fuels, especially PKS is the main driving force for the increasing demand for PKS. Even oil-rich countries with economies driven from oil (petrodollars) are also gradually implementing the decarbonization program.

To be used as fuel or further processed into a number of derivative products such as torrified PKS, PKSC or palm kernel shell charcoal and activated carbon, the PKS must be dried first. The process of drying or reducing the moisture content to a certain level requires energy. PKS, which are palm oil mill waste, are generally just piled up in the backyard of the palm oil mill, so they are usually dirty and wet, resulting in a low selling price. If the palm oil mill can dry and clean its PKS, the selling price will also increase, so that there is added value as well as additional income for the palm oil mill. A number of energy sources from waste heat from palm oil mills can be used for the drying process.

Heat is an energy source that can be used for various purposes, either heat generated directly from the combustion process or from waste heat which is the residual heat from the combustion or other sources such as electricity and so on. In palm oil mill operations there is a certain amount of waste heat that can be extracted or harvested or recovered as a heat source for drying such as heat from combustion in the boiler, heat from steam turbine and heat from the FFB sterilization process. If the palm oil mill also processes its liquid waste for electricity production, the waste heat from burning biogas in the generator can also be used as a heat source for drying the PKS. A number of heat sources which are waste heat when integrated, the amount is large so that it can be sufficient for drying the PKS.

In addition to producing CPO (Crude Palm Oil) as the main product, palm oil mills generally also produce palm kernel. Currently, there are still a few palm oil mills (CPO mills) that also have PKO (Palm Kernel Oil) mills , meaning that there are palm oil mills that process fiber for CPO production and palm kernel for PKO production. The palm kernel is produced from the separation of palm kernel with its shell (PKS). Separation is done by breaking the palm kernel shell in a nut cracker drum, then it can be separated between the palm kernel shell and the kernel or core based on differences in specific gravity. If the palm oil mill wants to get added value from its palm kernel shells (PKS), then as soon as it leaves the palm oil mill it goes straight into the dryer (with waste heat as the heat source) after which it is cleaned with a sieve (screening) so that it becomes the final product in the form of dry and clean PKS, so that higher sale value. The size of the shell and fibers that pass the sieve (undersize), can also be used as boiler fuel. Palm oil mill boilers currently operate using fiber fuel (mesocarp fiber) and part of the palm kernel shell (PKS). The rejected material in the form of undersize can be used as boiler fuel so that less PKS are used.

Post Mining Land Reclamation With Bamboo

Bamboo is a tree that is easy to grow, tall quickly and has many benefits. One of them is the use of bamboo trees for post-mining land reclamation. Damaged and barren post-mining land is indeed not easy to plant directly. Certain treatments or efforts are needed so that the land can be planted with certain plants. When the land has become fertile soil, of course almost all plants can be planted on the land. And to achieve these conditions it takes time and a process that is not short.

Soil improvement efforts in the sense of improving soil fertility are the first thing to do so that plants can grow well on the land. Plants that can be planted at this stage are also only certain types of plants such as pioneer plants in the form of fast growing plants such as legumes. And bamboo as a group of grass plants is also easy to plant and grow on marginal lands such as post-mining land. Availability of water, adequate nutrients, pH or adequate soil acidity are some of the things needed to achieve optimal growth.

As an illustration, sand is a bad planting medium because there are almost no nutrients in it and this is almost the same as the condition of post-mining land in general. Substances or organic materials need to be added so that they become fertilizers or nutrients for the land. Animal dung is the best organic material for this, so integration with livestock is the best concept for post-mining land reclamation. Biochar with its various advantages also needs to be added to the land. Biochar can be produced from biomass wastes from plantations, agriculture and forestry for this purpose. The use of biochar on a wide scale can also provide income in the form of carbon credits because biochar is applied to the soil as a carbon sink with carbon sequestration.

Bamboo trees as a type of grass plant have fibrous roots. Large bamboo clumps have a large network of fibrous roots as well. The success of bamboo roots is one of the keys to bamboo growth. The use of biochar in bamboo nurseries will also improve the roots of the bamboo seedlings produced. While in bamboo plantations, the use of biochar also has many benefits, especially on post-mining land the results will look more real, such as maintaining moisture, more available nutrients, not acidic soil pH and so on. Biochar is useful for improving soil fertility, so it can be used in nurseries and plantations.

Currently a number of mining companies have carried out land reclamation with these trees, but most of them are still testing and do not yet have a comprehensive concept. Post-mining land reclamation with bamboo in Indonesia is estimated to start in 2010 or has been going on for about 12 years until now. A number of bamboo species have also been identified as suitable for the post-mining area. Scale up or capacity enlargement is an important and current challenge, especially when it is supported by information on 12 years of reclamation with these bamboo trees. With this capacity expansion, besides bamboo production, commercial production can also be achieved, the application of biochar will also find its optimum benefits, namely improving soil fertility and carbon sinks (carbon sequenstration).

The use of bamboo in particular is an aspect that has not received serious attention in these reclamation projects. Whereas only with the use of bamboo which is a plantation product can the reclamation effort be known to provide economic benefits or not. The lack of serious attention to the use of bamboo is thought to be because the bamboo reclamation is still in the experimental stage with a small area. But if it has been pursued professionally, the economic aspect will become an important concern.

The use of bamboo, for example, is to make people's houses around the mine. With bamboo treated first and also using the art of building architecture, the bamboo house produced will be of high quality, in the sense of being sturdy and beautiful and far from being cheap. This will reduce the use of certain wood for houses, some of which have limited types, such as ironwood in Kalimantan. Indeed, there are many ways to use the bamboo, but it is necessary to choose the best one based on the related conditions and situations. Ruminant farming, especially for the production of organic matter or land fertilizers, will also require cages or in rotational grazing, poles for paddock will also be required. The cages and poles can also be made with these bamboo products.

And when bamboo production is used for biomass production and then used for biochar production, it is also technically possible. But economically, it is necessary to study whether it also provides benefits, both from the effect of improving soil fertility and carbon credit. In this case, the most important thing is the production of the biomass itself so that the bamboo species that produce the most biomass are selected. The more soils that can be repaired with biochar treatment, the more land that can be recovered so that it becomes productive land. When the soil is fertile again, various food crops are also very possible to be planted on the land. The increasing population also demands more food needs, so food production needs to be increased, including the use of these recoverable lands.

Wood Pellet Production from Acacia Industrial Plantation Forest (HTI) Waste

Acacia forests or plantations in Indonesia are estimated to reach 2 million hectares and almost all of these acacia forests are used to supply pulp and paper mills. Every pulp and paper mill always has acacia forest with an area of ​​​​thousands of hectares to meet the pulp and paper mill. Acacia wood with a minimum diameter of 8 cm is used as the raw material, while those with a diameter smaller than that are only used as waste. After the tree is cut down, then a new planting is carried out (replanting). If every one hectare produces 20 tons of acacia wood waste, then with an area of ​​20,000 hectares, 400,000 tons of acacia wood waste is produced. The area of ​​20,000 hectares of acacia plantations is not too big, this is because there are a number of HTI (industrial plantation forest) concession holders which cover an area of ​​hundreds of thousands of hectares, so the volume of wood waste produced is also very large. The wood waste is very potential for the production of wood pellets. The need for wood pellets is also increasing along with the decarbonization program or fossil fuel substitution.

Wood products come from different parts of the tree, each tree has a unique potential, depending on a number of factors including the diameter and straightness of the trunk. In acacia trees trunk diameter is the main parameter.

For the production of wood pellets, you can use raw materials from wood waste or wood that worth of waste wood. This is why wood that is valuable or has a high economy is not suitable for the production of wood pellets (from an economic point of view). Users of wood pellets are mainly for power plants so that the volume of their needs is large. Waste wood such as from acacia plantations is very potential and suitable for the production of large capacity wood pellets. In addition to Japan and Korea as the largest wood pellet market in Asia, currently Europe is also increasingly being encouraged to use wood pellets. The occurrence of the Russia-Ukraine war was one of the driving forces. The dependence on fossil fuels from Russia has become a concern for European countries in particular, so that the urge to use renewable energy is getting bigger. Biomass, especially wood pellets, also has a large portion in the plan to use renewable energy in Europe, especially in the RED (Renewable Energy Directive) II. Even in the current war conditions, the need for wood pellets for space heating is also getting bigger, although for this segment, especially firewood is their main fuel. With the disruption of energy supply from Russia, it is predicted that this winter will be a tough winter in Europe.

PKSC For Activated Carbon Production

The production of palm kernel shells (PKS) in Indonesia and Malaysia is very large, with more than 15 million tons annually which comes from palm oil mill waste. There are about 20 million hectares of palm oil plantation from these two countries (Indonesia and Malaysia) as sources of crude palm oil and are the largest in the world today. Utilization of PKS can be optimized for the production of activated carbon. The demand for activated carbon is predicted to increase by around 10% per year and the demand will reach nearly 4 million tons in 2021 worth 8.12 billion USD, while data in 2015 recorded global activated carbon production of around 2.7 million tons worth 4.74 billion USD. Powdered activated carbon (PAC) has the largest market share followed by granular activated carbon (GAC). The high demand for PAC is mainly driven by the need in a number of industries such as chemical, petrochemical, food and beverage for decolorizarion and deodorization applications. More specifically, the use in the liquid phase has the largest portion.

However, it is recognized that coconut shell is the current favorite material for activated charcoal production, and PKS is likely to be the next priority. The area of ​​Indonesian coconut plantations is estimated at around 3.7 million hectares so that the number of coconut shells that can be used as activated carbon is also not as much as PKS because the area of Indonesian palm oil plantations has also reached approximately 15 million hectares. With a coconut plantation area of 3.7 million hectares, coconut shells have a composition of 12% of coconuts so that the total coconut shells that can be produced are around 23,000 tons/year. This is in stark contrast to PKS which have the potential to reach tens of millions of tons every year.

The characteristics of coconut shells are also almost the same as PKS. Likewise for the use of activated carbon which emphasizes factors such as hardness and ash content. The harder the material and the smaller the ash content, the better the quality of activated carbon produced. Currently there is a need for palm kernel shell charcoal / PKSC  of 20,000 tons / year for the raw material for the production of activated carbon. Groups of palm oil companies that have a number of palm oil mills (1 group of palm oil companies having 5 palm oil mills is common in Indonesia) or other private parties by taking raw material for PKS from these palm oil mills to be able to produce PKSC to be exported as raw material for the activated production. The use of a large capacity carbonization (pyrolysis) equipment that works continuously is needed to meet these needs. This will be a business development for the palm oil companies and will be more environmentally friendly because less solid biomass waste is produced.

Complete Pellet Production Line (Fuel and Feed) Small Capacity For Research and Experiment

Laboratory equipment as a production unit or as a small factory (mini-mill) is needed both for learning (research and experiment) and as a production stage before reaching the commercial stage of a business. By observing and conducting trials on the mini-mill, in addition to getting a complete understanding of the production process from A to Z, we can also make detailed and in-depth observations of each stage of production in an easy and inexpensive way and provide a more complete picture for the commercial production process later. It is also easy to do research and experimentation on various kinds of raw materials, both single material and a mixture of several raw materials. Currently, there are many researchers and practitioners who want to try a raw material to make pellets but have difficulty finding partners or companies that can do it. Setting up equipment with mini-mill facilities is also much easier, in contrast to large factories. This is why in general large factories do not want to accept trials of making pellets from a certain material, because their focus is on production targets, unless they have R & D facilities for these trials.

Meanwhile, if the laboratory equipment is only in the form of functional tools such as cutting tools, crushing tools and so on but is not integrated into a production unit (even though the capacity is small), it will be difficult to imagine even more accurately designing an industrial or commercial factory. Even if a number of functional tools in the laboratory are integrated, which usually come from a number of manufacturers and have different capacities, operating the assembled mini mill is also not easy. That is why it is important to establish a complete line for the production of these pellets. The resulting pellet production can also be of two kinds, namely fuel pellets such as wood pellets and feed pellets such as leaf pellets, depending on the raw materials used.

And indeed on a commercial scale or large factory the pelletiser specification for fuel pellets such as wood pellets is different from the pelletiser for feed pellets. Pelletisers for fuel pellets such as in wood pellet production have a greater electric motor power about 3 times than a pelletiser for feed pellet production, for example for 1 ton/hour wood pellets need 150 KW while for feed pellets it is only 50 KW. In addition, the quality of the metal used for the production of the pelletiser is usually also different because the level of hardness of the raw materials is also different. Pelletiser is the main equipment or the heart of the process in pellet production, both fuel pellets (wood pellets) and feed pellets. Based on experience in the field, it turns out that there are many cases of failure of commercial wood pellet production due to errors in the selection of this pelletiser, namely the pelletiser for feed is used for wood pellets besides being not optimal, the machine life is short, even in a number of cases wood pellets are not formed so that the target production is not achieved. The main reason why this happened is because of being tempted by the price issue, namely the feed pelletiser is cheaper and in appearance it is also difficult to distinguish (especially the common people).

In this small capacity pellet production, only one type of pelletiser is used, because the main purpose is more on the qualitative aspect, not on the quantitative aspect. A number of process stages in the production of fuel pellets (wood pellets) are also very similar to the production of feed pellets, so the equipment used is also similar or even the same. This is mainly so that the price of the production unit is not too expensive. In commercial pellet production, ring die pelletisers are more widely and commonly used than flat die types. However, because the ring die pelletiser is more expensive even though it is close to the real conditions of the pellet industry, the flat die pelletiser is also sufficient for the purpose at this stage.

Feed pellets have a longer history than fuel pellets, especially wood pellets, namely in the 1920s when Purina Animal Nutrition, one of the largest animal feed producers in the world today. With this pelletization, the material is in powder form, unpalatable by livestock , different densities become easier to use and increase uniformity. This pelletization technique was quickly in great demand by many feed producers, so that in 1930 there were a number of feed factories specializing in the production of these feed pellets. World feed pellet production also far exceeds fuel pellets (wood pellets), which is in the range of 1 billion tons per year, while wood pellets are in the range of 50 million tons per year. Both have strategic functions in human life. Feed pellets as a food chain for humans are needed and their production continues to be increased. 

It is estimated that protein needs in 2050 need an additional 250 million tons per year, an increase of 50% compared to today. This is because according to the United Nations, the global human population is predicted to reach 9 billion people by 2050. The food sector is looking for a solution to the protein deficit due to protein demand per capita and population growth. Meanwhile, fuel pellets (wood pellets) are needed to save the earth from climate change. Wood pellets as carbon neutral fuel make it not increase the concentration of CO2 in the atmosphere which is a greenhouse gas that heats the earth's temperature. Decarbonization programs or substitution of fossil fuels for renewable energy, especially biomass fuel or wood pellets, continue to be improved throughout the world, as a reference you can read here and here. Energy plantations or legume plantations will be the solution to this problem, read in more detail here. 

 

In addition to pellet production (both fuel pellets and feed pellets) with a slight modification, namely replacing the pelletiser with a briquette machine, it can also be used for briquette production. This is because the production process is almost the same, the two technologies are the same, namely the biomass densification technology group. The use of these briquettes is also for fuel the same as wood pellets, but these briquettes can also be charred (carbonized) so that they become charcoal briquettes. The production of charcoal briquettes in this way produces better quality than the production of charcoal briquettes with charcoal as raw material and then added adhesive and pressed. This charcoal briquette product is commonly known in the market as sawdust charcoal briquette, the production of which does not require additional adhesive (binderless briquette).

Mini Palm Oil Mill Solution to Maximize FFB Processing

It is estimated that around 40% of palm oil plantations in Indonesia are owned by the people, this means that with the current area of palm oil plantations reaching around 15 million hectares, smallholder palm oil plantations reach about 6 million hectares with a total of 16 million smallholders. Of course the amount is not small, so if the palm fruit produced (Fresh Fruit Bunch / FFB) from the plantation can be processed optimally, it will increase the national production of crude palm oil or CPO. The area of ​6 million hectares itself is larger than Malaysia's palm oil plantation, which is the second largest producer of palm oil in the world, after Indonesia.

A number of FFB production from smallholder palm oil plantations are often constrained to supply to palm oil mills related to infrastructure and distance. This makes it take a long time or even too late to supply to the nearest palm oil mill, thus reducing the quality of palm fruit / FFB, automatically producing the crude palm oil. Low quality makes FFB prices cheap and even rejected by palm oil mills because they do not meet the required quality standards. This is certainly detrimental to farmers so that efforts are needed to overcome them.

Palm oil mills usually have a capacity of between 30 tons of FFB/hour to 120 tons of FFB/hour or it can be said that the average capacity is 60 tons of FFB/hour. The palm oil mill is owned by a palm oil company and with this capacity is very large for smallholders with limited palm oil plantation area. A mini palm oil mill with a capacity of 1 - 4 tons of FFB/hour is likely to be suitable for these smallholders. With this capacity, besides being cheaper, it requires narrower land and simpler production techniques so that FFB production from remote locations can be processed easily.

The palm oil production process can also be simplified or simplified so that it can be safe and easy to operate, for example in a large factory that uses high pressure steam, it can be simplified to only use low pressure steam. In large factories, high pressure steam is used to drive a steam turbine which is connected to a generator so as to generate electricity for the palm oil mill operation itself and the steam output from a low-pressure steam turbine is used for FFB sterilization. Meanwhile, if the mini mill has low pressure steam or only atmospheric steam, the steam is directly used for FFB sterilization, while the electricity for the operation of the mini palm oil mill comes from outside (external). With this mini capacity, the need for electricity for these operations is also not big.

The high quality of the palm oil produced can be obtained due to the quality of the raw materials and processes carried out. Good equipment performance also makes the process carried out according to the desired operating conditions. With the capacity of small palm oil mills, the volume of products produced is also small, so to achieve large volumes, it must be collected from a number of these mini palm oil mills. With more and more mini palm oil mills scattered in various locations, less FFB is wasted and quality palm oil products can be maintained. Cheap or falling FFB prices at the farmer level can also be overcome by mini palm oil mills that have good market access for their palm oil products.

Cocopeat and Biochar

Both cocopeat and biochar have uses in agriculture, but there are a number of differences between the two. Cocopeat is mainly used as a planting medium because of its water holding capacity, while biochar in addition to having the ability to hold water like cocopeat also raises soil pH, holds or makes nutrients more available (nutrient retention), and also becomes a colony of soil microbes so that organic matter becomes rapidly decomposed and absorbed by plants. Cocopeat will also decompose in a not too long time like compost while biochar can exist and not decompose for hundreds of years. Under these conditions, biochar is also used to store CO2 (carbon sequenstration) and obtain carbon credits with a carbon sink mechanism.

 

Choose Biochar or Cocopeat?
With these advantages, choosing biochar would be better. Moreover, the cocopeat can also be used for biochar production. The carbon removal program to reduce the concentration of CO2 in the atmosphere is also in line with the application of the biochar. Increasing global awareness of climate change and global warming makes carbon removal programs that also provide economic benefits from carbon credits likely to continue to increase in the near future. This cannot be done with cocopeat.

Converting cocopeat into biochar is also not difficult, even with a variety of simple (low tech) equipments it can be done. But for a large capacity so that the carbon credit program can run, it requires modern pyrolysis equipment with a large capacity. With this equipment, in addition to biochar production, there is also a number of excess energy that can be used for various purposes, one of which is drying cocopeat before it becomes raw material for biochar with such pyrolysis equipment.