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.  

Which is Better, Efficient Boiler or Pyrolysis System ?

Fiber and palm kernel shells (PKS) are palm oil mill solid wastes that are produced in CPO production in that mill. The amount of fiber and PKS waste is quite a lot, which is around 20% of each fresh fruit bunch (FFB) or almost the same as the CPO produced. A palm oil mill with a capacity of 60 tons / hour FFB can produce fiber as much as 8.1 tons per hour or 194.4 tons per day and PKS of 3.3 tons / hour per hour or 79.2 tons per day. And because both of them are waste, generally the utilization of the waste is not initially considered, including for use as fuel in boilers in palm oil mills for the production of electricity and steam. The use of fiber and PKS for boiler fuel generally uses 100% fiber and about 30% of the PKS. Under these conditions the remaining 70% of the PKS can be used for other things including being sold or even exported.

When the shell becomes a commercial commodity and demand is greater, palm oil mills replace their old inefficient boilers with new boilers that have a high level of efficiency. In this way, 100% of the PKS is no longer used to boiler fuel and only requires fiber as fuel. In this condition a paradigm shift in thinking begins to occur, that is when the solid waste is almost unnoticed and tends to be considered a problem, then it becomes an important part of earning additional income and it can even be estimated that if the shell is successfully sold then it is sufficient to cover the operational costs of the palm oil mill. Certainly something interesting if the production of CPO (crude palm oil) with 0% operational costs so that profit is increasingly attractive especially amid the recent decline in CPO prices.

Another thing that can be done is to use a pyrolysis unit, to run the boiler. With pyrolysis, not only fiber is used but also the empty fruit bunch (EFB). EFB are solid palm oil mill waste which to date have generally not been utilized. Besides producing energy, pyrolysis also produces products in the form of charcoal (biochar). Although charcoal (biochar) can also be used for energy sources, but in the business of palm oil companies the use of biochar for plantations can be more compatible. The use of biochar in palm oil plantations is mainly to  fertilizer saving, which is one of the major cost components (around 30%) in the CPO production business. With an area of ​​20 thousand hectares of oil palm plantations, fertilizer costs are estimated to reach Rp. 71.50 billion (around US$ 5 million) per year or Rp. 35.75 billion (around US$ 2.5 million) per year for every 10,000 hectares, for more details, please read here. Palm oil mills with big vision certainly try to maximize their potential with the aim of maximizing profits from upstream to downstream production activities. With Biochar can also target the increase in productivity of FFB, for more details, please read here.

The application of biochar will be easier to do in Indonesia than in Malaysia, this is because almost all palm oil mills in Indonesia also have palm oil plantations while in Malaysia the mills generally do not have their own palm oil plantations. The palm oil industry also has an important role for the two countries because Indonesia and Malaysia are the largest CPO producers and owners of biggest palm oil plantations in the world today. The palm oil industry contributes around 7% of Malaysian GDP and 3% of Indonesian GDP, so its role cannot be ignored. Both with pyrolysis and high efficient boilers, biomass waste can be used as an energy source and 100% of the PKS can be commercialized, but with pyrolysis is better because waste of EFB can also be processed, there are biochar product (while only ash if only with regular combustion) for Fertilizers saving in the palm oil plantations and the exhaust gases from the palm oil mill boilers are also clean because they burn gas (syngas) produced from the pyrolysis process.

Palm Kernel Shell Continuous Pyrolysis For Multipurpose Production

Production of palm kernel shells (PKS) which is palm oil mill waste in Indonesia approximately 9 million tons. Current utilization of 20% (1.8 million tons) for export, 15% (1.35 million tons) for internal use, 10% (0.9 million tons) for domestic (local) use, and the remaining 55% (4.95 million tons) yet used or become waste. Meanwhile, Indonesia's CPO production currently reaches 35.2 million tons, or 20% of FFB (Fresh Fruit Bunch), so the number of FFB (Fresh Fruit Bunch) produced in Indonesia currently ranges from 176 million tons. With an average productivity of 20 tons / hectare of FFB, so the FFB is generated from 8.8 million hectares. While the total area of ​​oil palm plantations in Indonesia is currently estimated to have almost 12 million hectares including unfruitful and unproductive age or need to be replanting. Another influential factor is the low level of productivity of oil palm plantations. Palm kernel shells are only about 6% of the FFB produced, and after is used for the internal CPO production process in the mill  with mesocarp, only about 4.5% of the palm kernel shell is the waste of the palm factory. From there it can also be calculated that every hectare of oil palm plantation will produce 1.2 tons or three quarters namely 0.9 tons of waste. With the current expansion of oil palm plantations up to 12 million hectares, the potential of palm kernel shells that become waste in the palm oil plant around 10.8 million tons or the amount of 10.8 million tons that can be used for export, fuel and production of various other products or external use.

Currently, there are a number of parties who have utilized the palm kernel shells for electricity production and boilers of some industries that are estimated to be less than 10% of the total produced palm shells. Some converting technologies into heat and electricity are used for processing such palm kernel shells. Combustion and gasification are technologies commonly used to convert or extract palm kernel shells into heat and electricity. Combustion technology in the furnace then combined ORC (Organic Rankine Cycle) and Stirling engine to convert it into electricity. While the gas from gasification is then used as fuel in gas engine to generate electricity. Are there any other options for processing the palm kernel shell so that it has bigger added value or more profitable?

Palm kernel shells are not suitable for biogas production because the lignoselulose material or rich lignin content material making it difficult to biologically decompose. The choice is pyrolysis or thermal decomposition with absence of oxygen. Pyrolysis is a technology that can to produce charcoal, biooil, pyro acid and syngas. This is what makes it possible for multipurpose production. Palm kernel shells such as rice husks, sawdust and the like are bulk materials also so will be suitable for continuous pyrolysis. How come? The answer is because there are several options for using the continuous pyrolysis:

1. Production of electricity and charcoal 

2. Production of electricity and activated charcoal

3. Production of electricity and charcoal briquettes

4. Production of charcoal and bio-chemicals

5. Production of charcoal and biofuel

6. Production of Charcoal and heat

At the production of electricity and charcoal, the process of excess syngas is used for electricity production, and charcoal is also produced as a solid product of pyrolysis. The charcoal can also be made briquette so it will be efficient during transportation and its use. As for the production of electricity and activated carbon, then excess syngas is used for the process of activation of the charcoal produced, with a more detailed explanation can be read here. In addition to charcoal, bio-chemicals such as acetic acid, methanol and phenol can also be produced by processing further byproducts namely pyro acid and syngas. Biofuels namely, biooil and syngas can also be additional products besides charcoal. Syngas can also be packed in a tube for ease of distribution and usage. Meanwhile, if syngas and biooil are burned it will generate heat, so if the business of charcoal production in combination with agriculture such as the use of green house or also farms that require a warm certain temperature the continuous pyrolysis unit becomes also very effective to be used. 

Charcoal production from palm kernel shells can also be a solution to the high export tax of palm kernel shells. By processing it into finished product then the tax should be decreased even eliminated because there has been industrialization which also absorb labor and encourage economic growth. In private power producers or IPP (Independent Power Producer), the additional product namely of charcoal will provide an increase business revenue, so that their business becomes more attractive business. In addition to charcoal production, if you want the production of high quality solid fuel (solid biomass fuel) namely by upgrading or processing it with torrefaction, can be done also with pyrolysis technology.

Upgrade PKS with Torrefaction

Application of the tax on PKS (Palm Kernel Shell) based on the Minister of Finance Indonesia No 67/2010 on stipulation of export goods subject duties (Bea Keluar/ BK) has made the selling price in the international market or the export market to be high. The amount of export duties and export taxes which value is currently around US $ 15 / ton, making a number of parties thought to do the processing of the PKS. Enforcement of the above regulations is also intended to encourage the growth of domestic industry. PKS categorized as raw materials, thus further processing into a solution to it. The selling price of PKS from Indonesia less competitive, when compared before, because it becomes much more expensive.

The use of palm shells (PKS) today especially for fuel of large scale power plant. And in particular Japan and Korea are much in need of the PKS. The need also tends greater for the next few years. Japan, especially in the next 1-2 years the need is predicted to increase sharply as the operation of power plants using biomass and part of PKS as a mixture (co-firing) with coal.

 Torrefaction is biomass processing to increase the calorific value and improve its characteristics. With torrefaction the energy content in biomass increased by 20% and conversion rate reached 70%, or nearly three times the carbonization conversion were an average of 25%.  In addition to the torrefaction then torrefied PKS product will be hydrophobic so that it does not absorb water / moisture.  This will make it easier in terms of handling and storage. Furthermore, by compaction (densification) into pellets torrified PKS, the density also will increase, as well as the energy content per volume of it. Pelleting torrified PKS will save significant transportation costs from the manufacturer to the user. JFBC technology is able to perform continuous torrefaction process, with a production capacity up to 140 tonnes per day of torrified PKS.