Biomass residue from palm oil industry are attractive renewable energy fuel in Southeast Asia. The abundance of these biomass resources is increasing with the fast development of palm oil industry in Malaysia, Indonesia and Thailand. In the Palm Oil value chain there is an overall surplus of by-products and the utilisation rate of these by-products is low.
Palm kernel shells (or PKS) are the shell fractions left after the nut has been removed after crushing in the palm oil mill. Palm kernel shells are a fibrous material and can be easily handled in bulk directly from the product line to the end use. Large and small shell fractions are mixed with dust-like fractions and small fibres.
Moisture content in kernel shells is low compared to other biomass residues with different sources suggesting values between 11% and 13%. Palm kernel shells contain residues of Palm Oil, which accounts for its slightly higher heating value than average lignocellulosic biomass. Compared to other residues from the industry, palm kernel shells are a good quality biomass fuel with uniform size distribution, easy handling, easy crushing, and limited biological activity due to low moisture content.
Press fibre and kernel shell generated by the palm oil mills are traditionally used as solid fuels for steam boilers. The steam generated is used to run turbines for electricity production. These two solid fuels alone are able to generate more than enough energy to meet the energy demands of a palm oil mill.
Most palm oil mills in the region are self-sufficient in terms of energy by making use of kernel shells and mesocarp fibers in cogeneration. The demand for palm kernel shells has increased considerably in Malaysia, Indonesia and Thailand resulting in price close to that of coal. Nowadays, cement industries are using palm kernel shells to replace coal mainly because of CDM benefits.
PKS has also emerged as a hot biomass commodity in the Asia-Pacific region, especially in South Korea and Japan, where PKS is being used to power huge biomass power plants. PKS is also getting traction in Europe as an attractive alternative fuel.
The problems associated with the burning of these solid fuels are the emissions of dark smoke and the carry-over of partially carbonized fibrous particulates due to incomplete combustion of the fuels can be tackled by commercially-proven technologies in the form of high-pressure boilers.
Dual-fired boilers capable of burning either diesel oil or natural gas are the most suitable for burning palm Oil waste since they could also facilitate the use of POME-derived biogas as a supplementary fuel. However, there is a great scope for introduction of high-efficiency CHP systems in the industry which will result in substantial supply of excess power to the public grid.
Malaysia is located in a region where biomass productivity is high which means that the country can capitalize on this renewable energy resource to supplements limited petroleum and coal reserves. Malaysia, as a major player in the palm oil and sago starch industries, produces a substantial amount of agricultural biomass waste which present a great opportunity for harnessing biomass energy in an eco-friendly and commercially-viable manner.
Peninsular Malaysia generates large amounts of wood and’ agricultural residues, the bulk of which are not being currently utilised for any further downstream operations. The major agricultural crops grown in Malaysia are rubber (39.67%), oil palm (34.56%), cocoa (6.75%), rice (12.68%) and coconut (6.34%). Out of the total quantity of residues generated, only 27.0% is used either as fuel for the kiln drying of timber, for the manufacture of bricks, the curing of tobacco leaves, the drying rubber-sheets and for the manufacture of products such as particleboard and fibreboard. The rest has to be disposed of by burning.
Palm Oil Industry
Oil palm is one of the world’s most important fruit crops. Malaysia is one of the largest producers and exporter of palm oil in the world, accounting for 30% of the world’s traded edible oils and fats supply. Palm oil industries in Malaysia have good potential for high pressure modern power plants and the annual power generation potential is about 8,000 GWh. Malaysia produced more than 20 million tonnes of palm oil in 2012 over 5 million hectares of land.
The palm oil industry is a significant branch in Malaysian agriculture. Almost 70% of the volume from the processing of fresh fruit bunch is removed as biomass waste in the form of empty fruit bunches (EFBs), fibers and shells, as well as liquid effluent. Fibres and shells are traditionally used as fuels to generate power and steam. Palm oil mill effluent, commonly known as POME, are sometimes converted into biogas that can be used in gas-fired gensets.
The cultivation of sugarcane in Malaysia is surprisingly small. Production is concentrated in the Northwest extremity of peninsular Malaysia in the states of Perlis and Kedah. This area has a distinct dry season needed for cost-efficient sugarcane production. Plantings in the states of Perak and Negri Sembilan were unsuccessful due to high unit costs as producing conditions were less suitable.
The lack of growth in cane areas largely reflects the higher remuneration received by farmers for other crops, especially oil palm. Over the past 20 years while the sugarcane area has remained at around 20000 hectares, that planted to oil palm has expanded from 600 000 hectares to 5 million hectares.
Other leading crops in terms of planted areas are rubber with 2.8 million hectares, rice with 670 000 hectares and cocoa with 380 000 hectares. Malaysia, the world’s third largest rubber producer, accounted for 1 million tons of natural rubber production in 2012. Like oil palm industry, the rubber industry produces a variety of biomass wastes whose energy potential is largely untapped until now.
Malaysia is gifted with conventional energy resources such as oil and gas as well as renewables like hydro, biomass and solar energy. As far as biomass resources in Malaysia are concerned, Malaysia has tremendous agricultural biomass and wood waste resources available for immediate exploitation. This energy potential of biomass resource is yet to be exploited properly in the country.
Taking into account the growing energy consumption and domestic energy supply constraints, Malaysia has set sustainable development and diversification of energy sources, as the economy’s main energy policy goals. The Five-Fuel Strategy recognises renewable energy resources as the economy’s fifth fuel after oil, coal, natural gas and hydro. Being a major agricultural commodity producer in the region Malaysia is well positioned amongst the ASEAN countries to promote the use of biomass as a source of renewable energy.
Major Biomass Resources in Malaysia
Agricultural crops e.g. sugarcane, cassava, corn
Agricultural residues e.g. rice straw, cassava rhizome, corncobs
Woody biomass e.g. fast-growing trees, wood waste from wood mill, sawdust
Malaysia is the world’s leading exporter of palm oil, exporting more than 19.9 million tonnes of palm oil in 2017. The extraction of palm oil from palm fruits results in a large quantity of waste in the form of palm kernel shells, empty fruit bunches and mesocarp fibres. In 2011, more than 80 million tons of oil palm biomass was generated across the country.
13MW biomass power plant at a palm oil mill in Sandakan, Sabah (Malaysia)
Processing crude palm oil generates a foul-smelling effluent, called Palm Oil Mill Effluent or POME, which when treated using anaerobic processes, releases biogas. Around 58 million tons of POME is produced in Malaysia annually, which has the potential to produce an estimated 15 billion m3 of biogas.
Rice husk is another important agricultural biomass resource in Malaysia with very good energy potential for biomass cogeneration. An example of its attractive energy potential is biomass power plant in the state of Perlis which uses rice husk as the main source of fuel and generates 10 MW power to meet the requirements of 30,000 households.
Municipal Solid Wastes
The per capita generation of solid waste in Malaysia varies from 0.45 to 1.44kg/day depending on the economic status of an area. Malaysian solid wastes contain very high organic waste and consequently high moisture content and bulk density of above 200kg/m3. The high rate of population growth is the country has resulted in rapid increase in solid waste generation which is usually dumped in landfills.
Biomass resources have long been identified as sustainable source of renewable energy particularly in countries where there is abundant agricultural activities. Intensive use of biomass as renewable energy source in Malaysia could reduce dependency on fossil fuels and significant advantage lies in reduction of net carbon dioxide emissions to atmosphere leading to less greenhouse effect. However, increased competitiveness will require large-scale investment and advances in technologies for converting this biomass to energy efficiently and economically.
During the production of crude palm oil, large amount of waste and by-products are generated. The solid waste streams consist of empty fruit bunch (EFB), mesocarp fruit fibers (MF) and palm kernel shells (PKS). Reuse of these waste streams in applications for heat, steam, compost and to lesser extent power generation are practised widely across Southeast Asia.
POME or Palm Oil Mill Effluent is an underutilized liquid waste stream from palm oil mills which is generated during the palm oil extraction/decanting process and often seen as a serious environmental issue but it is a very good source for biomethane production. Therefore, discharge of POME is subject to increasingly stringent regulations in many palm oil-producing nations.
Anaerobic Digestion of POME
POME is an attractive feedstock for biomethane production and is abundantly available in all palm oil mills. Hence, it ensures continuous supply of substrates at no or low cost for biogas production, positioning it as a great potential source for biomethane production. (Chin May Ji, 2013).
Palm oil mill effluent is a colloidal suspension containing 95-96% water, 0.6-0.7% oil and 4-5% total solids, which include 2-4% suspended solids. Biological Oxygen Demand (BOD) generally ranges between 25,000 and 65,714 mg/L, Chemical Oxygen Demand (COD) ranges between 44,300 and 102,696 mg/L.
Most palm oil mills and refineries have their own treatment systems for POME, which is easily amenable to biodegradation due to its high organic content. The treatment system usually consists of anaerobic and aerobic ponds. (Sulaiman, 2013).
Open pond systems are still commonly applied. Although relatively cheap to install, these system often fail to meet discharge requirements (due to lack of operational control, long retention time, silting and short circuiting issues).
Moreover, the biogas produced during the anaerobic decomposition of POME in open pond systems is not recovered for utilization. The produced gas dissipates into the atmosphere where it causes adverse environment effects (due to the fact that CH4 is a twenty times stronger greenhouse gas then CO2 (Chin May Ji, 2013).
Biogas from POME can be carried out using a number of various technologies ranging in cost and complexity. The closed-tank anaerobic digester system with continuous stirred-tank reactor (CSTR), the methane fermentation system employing special microorganisms and the reversible flow anaerobic baffled reactor (RABR) system are among the technologies offered by technology providers. (Malaysian Palm Oil Board, 2015).
Biogas production largely depends on the method deployed for biomass conversion and capture of the biogas, and can, therefore, approximately range from 5.8 to 12.75 kg of CH4 per cubic meter of POME. Application of enclosed anaerobic digestion will significantly increase the quality of the effluent/ discharge stream as well as the biogas composition, as mentioned in table below.
Table: Performance comparison between open and closed digester systems
Open digester system
Closed anaerobic digester
COD removal efficiency (%)
Released to atmosphere
Methane yield (kg CH4/kg COD removed)
Methane content (%)
Solid discharge (g/L)
*This table has been reproduced from (Alawi Sulaiman, 2007)
A closed anaerobic system is capable of producing and collecting consistently high quality of methane rich biogas from POME. Typical raw biogas composition will be: 50-60 % CH4, 40-50 % CO2, saturated with water and with trace amounts of contaminants (H2S, NH3, volatiles, etc.).
Biomethane Potential in Southeast Asia
The amount of biomethane (defined as methane produced from biomass, with properties close to natural gas) that can be potentially produced from POME (within the Southeast Asian region) exceeds 2.25 billion cubic meter of biomethane (on a yearly basis).
Especially Indonesia and Malaysia, as key producers within the palm oil industry, could generate significant quantities of biomethane. An impression of the biomethane potential of these countries including other feedstock sources is being highlighted below (VIV Asia, 2015).
Indonesia (4.35 billion m3 of biomethane):
25 billion m3 of biomethane from Palm Oil Mill Effluent (POME).
The Asian Pacific Biogas Alliance estimates that the potential of conversion of biomass to biomethane is sufficient to replace 25 percent of the natural gas demand by renewable biogas (Asian Pacific Biogas Alliance, 2015).
To sum up, due to the high fraction of organic materials, POME has a large energetic potential. By unlocking the energetic potential of these streams through conversion/ digesting and capture of biomethane, plant owners have the opportunity to combine waste management with a profitable business model.
Co-Authors: H. Dekker and E.H.M. Dirkse (DMT Environmental Technology)
Alawi Sulaiman, Z. B. (2007). Biomethane production from pal oil mill effluent (POME) in a semi-commercial closed anaerobic digester. Seminar on Sustainable Palm Biomass initiatives. Japan Society on Promotion of Science (JSPS).
Asia Biogas Group. (2015, 08 15). Retrieved from Asia Biogas : http://www.asiabiogas.com
Asian Pacific Biogas Alliance. (2015). Biogas Opportunities in South East Asia. Asian Pacific Biogas Alliance/ICESN.
Chin May Ji, P. P. (2013). Biogas from palm oil mill effluent (POME): Opportunities and challenges from Malysia’s perspective. Renewable and Sustainable Energy Reviews , 717-726.
Malaysian Palm Oil Board. (2015, 08 26). Biogas capture and CMD project implementation for palm oil mills. Retrieved from Official Portal Of Malaysian Palm Oild Board:
Sulaiman, N. A. (2013). The Oil Palm Wastes in Malaysia. In M. D. Matovic, “Biomass Now – Sustainable Growth and Use”. InTech.
VIV Asia. (2015, 08 26). The international platform from feed to food in Asia. Retrieved from http://www.vivasia.nl
Note: This is the first article in the special series on ‘Sustainable Utilization of POME-based Biomethane’ by Langerak et al of DMT Environmental Technology (Holland)
Southeast Asia, with its abundant bioenergy resources, holds a strategic position in the global biomass energy atlas. There is immense biomass energy potential in Southeast Asian countries due to plentiful supply of diverse forms of biomass wastes, such as agricultural residues, woody biomass, animal wastes, municipal solid waste, etc. The rapid economic growth and industrialization in the region has accelerated the drive to implement the latest waste-to-energy technologies to tap the unharnessed potential of biomass resources.
Southeast Asia is a big producer of agricultural and wood products which, when processed in industries, produces large amounts of biomass residues. According to conservative estimates, the amount of biomass residues generated from sugar, rice and palm oil mills is more than 200-230 million tons per year which corresponds to cogeneration potential of 16-19 GW.
Rice mills in the region produce 38 million tonnes of rice husk as solid residue which is a good fuel for producing heat and power. Sugar industry is an integral part of the industrial scenario in Southeast Asia accounting for 7% of sugar production worldwide. Sugar mills in Thailand, Indonesia, Philippines and Vietnam generate 34 million tonnes of bagasse every year. Malaysia, Indonesia and Thailand account for 90% of global palm oil production leading to the generation of 27 million tonnes of waste per annum in the form of empty fruit bunches (EFBs), fibers and shells, as well as liquid effluent.
Woody biomass is a good energy resource due to presence of large number of forests in Southeast Asia. Apart from natural forests, non-industrial plantations of different types (e.g. coconut, rubber and oil palm plantations, fruit orchards, and trees in homesteads and gardens) have gained recognition as important sources of biomass. In addition, the presence of a large number of wood processing industries also generates significant quantity of wood wastes. The annual production of wood wastes in the region is estimated to be more than 30 million m3.
The prospects of biogas power generation are also high in the region, thanks to presence of well-established food-processing and dairy industries. Another important biomass resource is contributed by municipal solid wastes in heavily populated urban areas. In addition, there are increasing efforts both commercially and promoted by governments to develop biomass energy systems for efficient biofuel production, e.g. bio-diesel from palm oil.
Biomass resources, particularly residues from forests, wood processing, agricultural crops and agro-processing, are under-utilised in Southeast Asian countries. There is an urgent need to utilize biomass wastes for commercial electricity and heat production to cater to the needs of the industries as well as urban and rural communities.
Southeast Asian countries are yet to make optimum use of the additional power generation potential from biomass waste resources which could help them to partially overcome the long-term problem of energy supply. Technologies for biomass utilization which are at present widely used in Southeast counties need to be improved towards best practice by making use of the latest trends in the biomass energy sector.
Malaysia is blessed with abundant renewable sources of energy, especially biomass and solar. Under the Eighth Malaysian Plan, renewable energy was added in the energy mix to unveil a Five-Fuel Strategy to achieve 5 percent contribution by 2005.
Among the various sources of renewable energy, bioenergy seems to be the most promising option for Malaysia. The National Biofuel Policy, launched in 2006 encourages the use of environmentally friendly, sustainable and viable sources of biomass energy. Under the Five Fuel Policy, the government of Malaysia has identified biomass as one of the potential renewable energy.
Malaysia produces atleast 168 million tonnes of biomass, including timber and oil palm waste, rice husks, coconut trunk fibres, municipal waste and sugar cane waste annually. Being a major agricultural commodity producer in the region Malaysia is well positioned amongst the ASEAN countries to promote the use of biomass as a renewable energy source.
Malaysia has been one of the world’s largest producers and exporters of palm oil for the last forty years. The Palm Oil industry, besides producing Crude Palm Oil (CPO) and Palm Kernel Oil, produces Palm Shell, Press Fibre, Empty Fruit Bunches (EFB), Palm Oil Mill Effluent (POME), Palm Trunk (during replanting) and Palm Fronds (during pruning).
Malaysia has approximately 4 million hectares of land under oil palm plantation. Over 75% of total area planted is located in just four states, Sabah, Johor, Pahang and Sarawak, each of which has over half a million hectares under cultivation. The total amount of processed FFB (Fresh Fruit Bunches) was estimated to be 75 million tons while the total amount of EFB produced was estimated to be 16.6 million tons. Around 58 million tons of POME is produced in Malaysia annually, which has the potential to produce an estimated 15 billion m3 of biogas can be produced each year.
Malaysia is the world’s second largest producer of crude palm oil. Almost 70% of the volume from the processing of fresh fruit bunch is removed as wastes in the form of empty fruit bunches, palm kernel shells, palm oil mill effluent etc. With more than 451 mills in Malaysia, this palm oil industry generate around 100 million dry tonnes of biomass. Malaysia has more than 2400 MW of biomass and 410 MW of biogas potential, out of which only a fraction has been harnessed until now.
Rice husk is another important agricultural biomass resource in Malaysia with good potential for power cogeneration. An example of its attractive energy potential is biomass power plant in the state of Perlis which uses rice husk as the main source of fuel and generates 10 MW power to meet the requirements of 30,000 households. The US$15 million project has been undertaken by Bio-Renewable Power Sdn Bhd in collaboration with the Perlis state government, while technology provider is Finland’s Foster Wheeler Energia Oy.
Under the EC-ASEAN Cogeneration Program, there are three ongoing Full Scale Demonstration Projects (FSDPs) – Titi Serong, Sungai Dingin Palm Oil Mill and TSH Bioenergy – to promote biomass energy systems in Malaysia. The 1.5MW Titi Serong power plant, located at Parit Buntar (Perak), is based on rice husk while the 2MW Sungai Dingin Palm Oil Mill project make use of palm kernel shell and fibre to generate steam and electricity. The 14MW TSH Bioenergy Sdn Bhd, located at Tawau (Sabah), is the biggest biomass power plant in Malaysia and utilizes empty fruit bunches, palm oil fibre and palm kernel shell as fuel resources.
Palm Oil processing gives rise to highly polluting wastewater, known as Palm Oil Mill Effluent (POME), which is often discarded in disposal ponds, resulting in the leaching of contaminants that pollute the groundwater and soil, and in the release of methane gas into the atmosphere. POME is an oily wastewater generated by palm oil processing mills and consists of various suspended components. This liquid waste combined with the wastes from steriliser condensate and cooling water is called palm oil mill effluent.
On average, for each ton of FFB (fresh fruit bunches) processed, a standard palm oil mill generate about 1 tonne of liquid waste with biochemical oxygen demand 27 kg, chemical oxygen demand 62 kg, suspended solids (SS) 35 kg and oil and grease 6 kg. POME has a very high BOD and COD, which is 100 times more than the municipal sewage.
POME is a non-toxic waste, as no chemical is added during the oil extraction process, but will pose environmental issues due to large oxygen depleting capability in aquatic system due to organic and nutrient contents. The high organic matter is due to the presence of different sugars such as arabinose, xylose, glucose, galactose and manose. The suspended solids in the POME are mainly oil-bearing cellulosic materials from the fruits. Since the POME is non-toxic as no chemical is added in the oil extraction process, it is a good source of nutrients for microorganisms.
Biogas Potential of POME
POME is always regarded as a highly polluting wastewater generated from palm oil mills. However, reutilization of POME to generate renewable energies in commercial scale has great potential. Anaerobic digestion is widely adopted in the industry as a primary treatment for POME. Biogas is produced in the process in the amount of 20 m3 per ton FFB. This effluent could be used for biogas production through anaerobic digestion. At many palm oil mills this process is already in place to meet water quality standards for industrial effluent. The gas, however, is flared off.
Palm oil mills, being one of the largest industries in Malaysia and Indonesia, effluents from these mills can be anaerobically converted into biogas which in turn can be used to generate power through CHP systems such as gas turbines or gas-fired engines. A cost effective way to recover biogas from POME is to replace the existing ponding/lagoon system with a closed digester system which can be achieved by installing floating plastic membranes on the open ponds.
As per conservative estimates, potential POME produced from all Palm Oil Mills in Indonesia and Malaysia is more than 50 million m3 each year which is equivalent to power generation capacity of more than 800 GW.
Recovery of organic-based product is a new approach in managing POME which is aimed at getting by-products such as volatile fatty acid, biogas and poly-hydroxyalkanoates to promote sustainability of the palm oil industry. It is envisaged that POME can be sustainably reused as a fermentation substrate in production of various metabolites through biotechnological advances. In addition, POME consists of high organic acids and is suitable to be used as a carbon source.
POME has emerged as an alternative option as a chemical remediation to grow microalgae for biomass production and simultaneously act as part of wastewater treatment process. POME contains hemicelluloses and lignocelluloses material (complex carbohydrate polymers) which result in high COD value (15,000–100,000 mg/L).
Utilizing POME as nutrients source to culture microalgae is not a new scenario, especially in Malaysia. Most palm oil millers favor the culture of microalgae as a tertiary treatment before POME is discharged due to practically low cost and high efficiency. Therefore, most of the nutrients such as nitrate and ortho-phosphate that are not removed during anaerobic digestion will be further treated in a microalgae pond. Consequently, the cultured microalgae will be used as a diet supplement for live feed culture.
In recent years, POME is also gaining prominence as a feedstock for biodiesel production, especially in the European Union. The use of POME as a feedstock in biodiesel plants requires that the plant has an esterification unit in the back-end to prepare the feedstock and to breakdown the FFA. In recent years, biomethane production from POME is also getting traction in Indonesia and Malaysia.
Europe is targeting an ambitious renewable energy program aimed at 20% renewable energy in the energy mix by 2020 with biomass energy being key renewable energy resource across the continent. However, the lack of locally-available biomass resources has hampered the progress of biomass energy industry in Europe as compared with solar and wind energy industries. The European biomass industry is largely dependent on wood pellets and crop residues.
Europe is the largest producer of wood pellets, which is currently estimated at 13.5 million tons per year while its consumption is 18.8 million tons per year. The biggest wood pellet producing countries in Europe are Germany and Sweden. Europe relies on America and Canada to meet its wood pellet requirements and there is an urgent need to explore alternative biomass resources. In recent years, palm kernel shells (popularly known as PKS) from Southeast Asia and Africa has emerged as an attractive biomass resources which can replace wood pellets in biomass power plants across Europe.
What are Palm Kernel Shells
Palm kernel shells are the shell fractions left after the nut has been removed after crushing in the Palm Oil Mill. Kernel shells are a fibrous material and can be easily handled in bulk directly from the product line to the end use. Large and small shell fractions are mixed with dust-like fractions and small fibres.
Moisture content in kernel shells is low compared to other biomass residues with different sources suggesting values between 11% and 13%. Palm kernel shells contain residues of Palm Oil, which accounts for its slightly higher heating value than average lignocellulosic biomass. Compared to other residues from the industry, it is a good quality biomass fuel with uniform size distribution, easy handling, easy crushing, and limited biological activity due to low moisture content.
Press fibre and shell generated by the palm oil mills are traditionally used as solid fuels for steam boilers. The steam generated is used to run turbines for electricity production. These two solid fuels alone are able to generate more than enough energy to meet the energy demands of a palm oil mill.
Advantages of Palm Kernel Shells
PKS has almost the same combustion characteristics as wood pellets, abundantly available are and are cheap. Indonesia and Malaysia are the two main producers of PKS. Indonesian oil palm plantations cover 12 million hectares in Indonesia and 5 million hectares in Malaysia, the number of PKS produced from both countries has exceeded 15 million tons per year. Infact, the quantity of PKS generated in both countries exceeds the production of wood pellets from the United States and Canada, or the two largest producers of wood pellets today.
Interestingly, United States and Canada cannot produce PKS, because they do not have oil palm plantations, but Indonesia and Malaysia can also produce wood pellets because they have large forests. The production of wood pellets in Indonesia and Malaysia is still small today, which is less than 1 million tons per year, but the production of PKS is much higher which can power biomass power plants across Europe and protect forests which are being cut down to produce wood pellets in North America and other parts of the world.
PKS as a Boiler Fuel
Although most power plants currently use pulverized coal boiler technology which reaches around 50% of the world’s electricity generation, the use of grate combustion boiler technology and fluidized bed boilers is also increasing. Pulverized coal boiler is mainly used for very large capacity plants (> 100 MW), while for ordinary medium capacity uses fluidized bed technology (between 20-100 MW) and for smaller capacity with combustor grate (<20 MW). The advantage of boiler combustion and fluidized bed technology is fuel flexibility including tolerance to particle size.
When the pulverized coal boiler requires a small particle size (1-2 cm) like sawdust so that it can be atomized on the pulverizer nozzle, the combustor grate and fluidized bed the particle size of gravel (max. 8 cm) can be accepted. Based on these conditions, palm kernel shells has a great opportunity to be used as a boiler fuel in large-scale power plants.
Use of PKS in pulverized coal boiler
There are several things that need to be considered for the use of PKS in pulverized coal boilers. The first thing that can be done is to reduce PKS particle size to a maximum of 2 cm so that it can be atomized in a pulverized system. The second thing to note is the percentage of PKS in coal, or the term cofiring. Unlike a grate and a fluidized bed combustion that can be flexible with various types of fuel, pulverized coal boilers use coal only. There are specific things that distinguish biomass and coal fuels, namely ash content and ash chemistry, both of which greatly influence the combustion characteristics in the pulverized system.
PKS has emerged as an attractive biomass commodity in Japan
Coal ash content is generally greater than biomass, and coal ash chemistry is very different from biomass ash chemistry. Biomass ash has lower inorganic content than coal, but the alkali content in biomass can change the properties of coal ash, especially aluminosilicate ash.
Biomass cofiring with coal in small portions for example 3-5% does not require modification of the pulverized coal power plant. For example, Shinci in Japan with a capacity of 2 x 1,000 MW of supercritical pulverized fuel with 3% cofiring requires 16,000 tons per year of biomass and no modification. Similarly, Korea Southeast Power (KOSEP) 5,000 MW with 5% cofiring requires 600,000 tons per year of biomass without modification.
PKS cofiring in coal-based power plants
Pulverized coal-based power plants are the predominant method of large-scale electricity production worldwide including Europe. If pulverised fuel power plants make a switch to co-firing of biomass fuels, it will make a huge impact on reducing coal usage, reducing carbon emissions and making a transition to renewable energy. Additionally, the cheapest and most effective way for big coal-based power plants to enter renewable energy sector is biomass cofiring. Palm kernel shells can be pyrolyzed to produce charcoal while coal will produce coke if it is pyrolyzed. Charcoal can be used for fuel, briquette production and activated charcoal.
The palm oil industry is particularly involved in the development of sustainability standards. Driven by growing global demand, palm oil production has expanded rapidly in the last few years. Palm oil is the most widely consumed vegetable oil in the world, and its popularity has grown even more with the emergence of new market opportunities in the biofuels sector, in addition to its traditional food and oleochemical uses.
This strong growth has unquestionably contributed to the economic development of the main producer countries – Indonesia and Malaysia – which account for 87% of global production. Palm oil cultivation provides income for many smallholders, whose produce accounts for around 40% of world palm oil output.
Environmental and Socio-economic Concerns
However, the expansion of palm oil cultivation has also generated serious environmental concerns. It results in tropical deforestation and thus has a major impact on biodiversity loss, with the decline of emblematic species such as orangutan in Southeast Asia. It contributes to climate change through deforestation, but also through the conversion of peatlands, which are of vital importance in soil carbon sequestration.
The huge forest and bush fires in recent years in Indonesia which are associated with clearing lands for agricultural or forestry plantations caused severe air pollution and public health problems across the sub-region. In addition, industrial plantations are sometimes responsible for polluting waterways, into which chemical inputs and processing plant waste are dumped.
Moreover, this expansion has sometimes resulted in social abuses and human rights violations, in the form of land grabbing by plantation companies at the expense of local and indigenous communities or of the exploitation of plantation workers.
Sustainability Standards in Oil Palm Industry
Condemnation of these abuses by NGOs and growing consumer awareness of the adverse impacts of the expansion of palm oil plantation have driven the development of sustainability standards. Such standards are aimed at transforming production practices in order to mitigate their adverse environmental and social effects.
The expansion of palm oil cultivation in Southeast Asia has also generated serious environmental concerns.
In 2001, representatives of the food processing and distribution sector launched a dialogue with WWF and plantation companies, leading to the creation in 2004 of the first voluntary sustainability standard in the sector, the Roundtable on Sustainable Palm Oil (RSPO).
There are now 2.41 million hectares of RSPO-certified plantations, while sustainable palm oil accounted for 20% of world trade in this product. Meanwhile, several other initiatives proposing a vision of palm oil sustainability have emerged, positioning themselves as either a complement or an alternative to RSPO.
New Challenges to Overcome
The development of these initiatives demonstrates the growing awareness among producers, the industry and the public authorities of the need to transform the sector to enable it to contribute to the Sustainable Development Goals (SDGs). But this proliferation of sustainability standards itself poses new challenges, even though the environmental and social problems that motivated their emergence remain unresolved.
At the institutional level, the proliferation of sustainability initiatives since the creation of RSPO reflects a real fragmentation of the regulatory framework. This proliferation also raises the question of the articulation of these voluntary standards with the public regulations and national sustainability standards that producer countries have adopted.
Finally, measures to ensure the sustainability of palm oil cultivation need to bolster their credibility by guaranteeing better inclusion of the millions of smallholders, and by contributing in an effective, measurable way to mitigating the adverse social and environmental impacts of growth in palm oil cultivation. In this field, the role of collaborative and multidisciplinary research in providing strong evidence-based impact evaluation of standards is crucial.