The present study investigates the quality changes of wood bio-briquette fuel after the addition of spent coffee ground (SCG) into the initial feedstock materials (sawdust, shavings) in different mass ratios (1:1, 1:3). Analysis of SCGs fuel parameter proved great potential for energy generation by a process of direct combustion. Namely, level of calorific value (GCV = 21.58 MJ·kg −1 ), of ash content (Ac = 1.49%) and elementary composition (C = 55.49%, H = 7.07%, N = 2.38%, O = 33.41%) supports such statement. A comparison with results of initial feedstock materials exhibited better results of SCG in case of its calorific value and elementary composition. Bulk density ρ (kg·m −3 ) and mechanical durability DU (%) of bio-briquette samples from initial feedstock materials were following for sawdust: ρ = 1026.39 kg·m −3 , DU = 98.44% and shavings: ρ = 1036.53 kg·m −3 , DU = 96.70%. The level of such mechanical quality indicators changed after the addition of SCG. Specifically, SCG+sawdust mixtures achieved ρ = 1077.49 kg·m −3 and DU = 90.09%, while SCG + shavings mixtures achieved ρ = 899.44 kg·m −3 and DU = 46.50%. The addition of SCG increased wood bio-briquettes energy potential but decreased its mechanical quality. Consequently, the addition of SCG in wood bio-briquette has advantages, but its mass ratio plays an important key role.Energies 2020, 13, 54 2 of 15 economics, politics, and the trade of many developing countries. The coffee production industry, i.e., plant cultivation, cherries harvest, bean processing, product packaging, sale marketing, and final product transportation, offers job opportunities for millions of people [5].Brazil belongs to the top countries in coffee production, as well as Vietnam, Indonesia, and Colombia. Together those countries generate more than 50% of the world's coffee production. Specific statistical data provided by the Food and Agriculture Organization of the United Nations (FAO) and by the International Coffee Organization (ICO) related to the coffee industry in the last years are expressed in Table 1.

The wood processing industry produces a significant amount of wood waste. Biomass valorization through pyrolysis has the potential to increase the added value of wood wastes. Pyrolysis is an important thermochemical process that can produce solid, liquid, and gas products. This paper aims to review the pyrolysis of wood wastes from Indonesia, including teak wood (Tectona grandis), meranti (Shorea sp.), sengon (Paraserianthes falcataria (L) Nielsen), and rubberwood (Hevea brasiliensis). The review is based on an in-depth study of reliable literatures, statistical data from government agencies, and direct field observations. The results showed that pyrolysis could be a suitable process to increase the added value of wood waste. Currently, slow pyrolysis is the most feasible for Indonesia, with the main product of charcoal. The efficiency of the slow pyrolysis process can be increased by harvesting also liquid and gaseous products. The use of the main product of pyrolysis in the form of charcoal needs to be developed and diversified. Charcoal is not only used for fuel purposes but also as a potential soil improvement agent.

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The present research describes an application of high-pressure briquetting technology to the waste management of sugarcane processing in Vietnam. The amount of generated sugarcane bagasse was monitored during sugarcane processing within the street juice production in Hue city, Vietnam. Generated sugarcane bagasse was subjected to fuel parameters analysis within its suitability for direct combustion. The obtained sugarcane bagasse was converted into bio-briquette fuel by a high-pressure briquetting press and its mechanical quality was determined. Results proved that the proportion of generated sugarcane bagasse from whole sugarcane stem mass was equal to 35.45%. This indicated generation of an abundant amount of sugarcane bagasse worldwide in general. Fuel parameters analysis proved high quality level of low ash content = 0.97% and high calorific values (gross calorific value = 18.35 MJ·kg-1, net calorific value = 17.06 MJ·kg-1), which indicated good suitability for direct combustion processes. Indicators of mechanical quality proved the following observations: mechanical durability = 99.29%, compressive strength = 150.82 N∙mm-1 and bulk density = 1022.44 kg·m-3, with all these indicators representing positive results. In general, the observed results indicated suitability of sugarcane bagasse valorization within the production of bio-briquette fuel by using high-pressure briquetting technology. Finally, analysis of such waste biomass proved its great potential for energy recovery, thus, the advantage of its valorization within the sustainable technologies.

Palm oil (Elaeis guineensis) is one of the agricultural biomass. Palm oil solid waste that is relatively easy to find is empty fruit bunches (EFB). EFB biomass is converted into pellets to get a uniform size, then heated through torrefaction into bioenergy so that its utilization is more optimal and can increase economic value. Torrefaction is slow heating of biomass with a temperature range of 200oC-300oC with a state of little oxygen or without oxygen. Torrefaction was carried out using an electric furnace with a target temperature of 280oC and a duration of 20 minutes. The purpose of this paper is to determine the effect of torrefaction on the chemical properties of EFB pellets. The results of this study are hemicellulose and cellulose decreased by 0,58% - 0,77%, this happens because hemicellulose and cellulose are degraded with increasing temperature and time of torrefaction. This is confirmed by changes in the line spectrum for FT-IR analysis where C-O, C=C, C-H, and O-H experience changes in the line spectrum that indicate changes in chemical composition. while lignin increased after torrefaction by 2,71%. Water content in EFB pellets decreased by 0,65%, while EFB pellets without treatment (control) by 14,95% after torrefaction became 22,70%. The volatile content of EFB control pellets was 69,55% after torrefaction to 61,21% so that the fixed carbon content of EFB control pellets was 10,03% and EFB pellets after torrefaction became 14,23%. The heat value of EFB pellets before torrefaction is 15,82 MJ/kg, and after torrefaction, the heating value increases to 18,28 MJ/kg so that it reaches the standard requirements of SNI 8675: 2018 as biomass pellets. Torrefaction pellets from EFB can provide a large increase in the quality of the bioenergy chemical properties. Biomass torrefaction is very suitable for combustion in power plants and home industries. Keywords:Chemical composition, FTIR,oil palm empty fruit bunches, torrefaction ABSTRAK Kelapa sawit (Elaeis guineensis) merupakan salah satu biomassa hasil pertanian. Limbah padat perkebunan sawit yang relatif mudah dijumpai ialah tandan kosong kelapa sawit (TKKS). Biomassa TKKS dikonversikan menjadi pelet untuk mendapatkan ukuran yang seragam, kemudian ditorefaksi untuk digunakan sebagai bioenergi sehingga pemanfaatannya lebih optimal dan dapat meningkatkan nilai ekonomi. Torefaksi merupakan pemanasan biomassa secara perlahan dengan kisaran suhu 200oC – 300oC dengan keadaan sedikit oksigen bahkan tanpa oksigen. Torefaksi dilakukan menggunakan electric furnace dengan target suhu 280oC dan durasi selama 20 menit. Tujuan dari penelitian ini ialah untuk mengetahui pengaruh torefaksi terhadap sifat kimia pelet TKKS. Hasil dari penelitian ini ialah kadar hemiselulosa dan selulosa menurun sebesar 0,58% - 0,77% hal tersebut terjadi karena hemiselulosa dan selulosa terdegradasi seiring dengan peningkatan suhu dan waktu torefaksi. Hal tersebut diperkuat dengan perubahan gugus fungsi terhadap analisis FT-IR dimana gugus C-O, C=C, C-H, dan O-H mengalami perubahan spektrum garis pita yang menandakan adanya perubahan komposisi kimia. Sedangkan kadar lignin meningkat setelah torefaksi sebesar 2,71%. Kadar air pada pelet TKKS menurun sebesar 0,65 %, sedangkan abu pelet TKKS tanpa perlakuan (kontrol) sebesar 14,95% setelah tertorefaksi menjadi 22,70. Zat terbang pelet TKKS kontrol sebesar 69,55% setelah tertorefaksi menjadi 61,21% sehingga diperoleh nilai karbon terikat pelet TKKS kontrol sebesar 10,03% dan pelet TKKS yang tertorefaksi sebesar 14,23%. Nilai kalor pelet TKKS sebelum torefaksi sebesar 15,82 MJ/kg, dan setelah torefaksi nilai kalor meningkat menjadi 18,28 MJ/kg sehingga memenuhi SNI 8675:2018 pelet biomassa. Pelet TKKS yang tertorefaksi dapat memberikan peningkatan besar dalam kualitas sifat kimia bioenergi. Biomassa yang tortorefaksi sangat cocok untuk pembakaran di pembangkit listrik dan industri.  Kata Kunci:  FTIR,komposisi kimia,tandan kosong kelapa sawit, torefaksi

Oil palm (Elaeis guineensis) empty fruit bunches (EFB) have not been utilized optimally. Currently, it is considered as a resource with low economic value. This biomass can be converted into bioenergy through a torrefaction process. Torrefaction is a mild pyrolysis at temperatures ranging between 200 and 300 °C, and it is generally performed under an inert atmosphere. The objective of this study was to evaluate the effects of torrefaction using Counter-Flow Multi Baffle (COMB) on the properties of oil palm EFB pellets. Torrefaction was conducted at 280 °C temperature with a residence time of 4 minutes. The results showed a decrease in the equilibrium moisture content and an increase in hydrophobicity after torrefaction using the COMB reactor. The change in the hygroscopic property could make the oil palm EFB pellet more stable against chemical oxidation and microbial degradation, hence self-heating and auto-ignition during storage could be prevented. The heating value of biomass increased after torrefaction. Torrefaction with the COMB reactor resulted in a heating value of 17.90 MJ/kg, which is comparable with the results of oxidative torrefaction (with longer residence time) of 18.28 MJ/kg. The results suggested that torrefaction using the COMB reactor could provide a great improvement in the quality of the bioenergetic properties of oil palm EFB pellets. However, the high ash content of the EFB pellets implied that the EFB pellets suitable for a small-scale application, but not yet for cofiring in power plants or as a feedstock for gasification.Keywords: Counter-Flow Multi Baffle; oil palm empty fruit bunches; renewable; torrefactionA B S T R A KTandan kosong kelapa sawit (Elaeis guineensis) belum dimanfaatkan secara optimal. Saat ini bahan tersebut masih dianggap sebagai sumber daya bernilai ekonomi rendah. Tandan kosong kelapa sawit (TKKS) dapat dikonversi menjadi bioenergi melalui proses torefaksi. Torefaksi merupakan proses pirolisis ringan pada suhu berkisar antara 200 dan 300 °C dan umumnya dilakukan di bawah kondisi inert. Penelitian ini bertujuan untuk mengetahui pengaruh torefaksi dengan reaktor Counter-Flow Multi Baffle (COMB) terhadap sifat-sifat pelet TKKS. Torefaksi dilakukan pada suhu 280 °C dengan waktu tinggal 4 menit. Hasil penelitian menunjukkan bahwa torefaksi menyebabkan penurunan kadar air kesetimbangan dan menjadi hidrofobik setelah torefaksi dengan reaktor COMB. Perbaikan sifat higroskopis dapat membuat pelet TKKS lebih stabil terhadap oksidasi kimia dan degradasi mikroba, sehingga pemanasan sendiri dan pembakaran spontan selama penyimpanan dapat dicegah. Nilai kalor biomassa meningkat setelah torefaksi. Torefaksi dengan reaktor COMB menghasilkan nilai kalor 17,90 MJ/kg, yang sebanding dengan hasil torefaksi oksidatif dengan waktu tinggal lebih lama, sebesar 18,28 MJ/kg. Hasil penelitian menunjukkan bahwa torefaksi dengan reaktor COMB dapat meningkatkan kualitas energi pelet TKKS. Tetapi pelet TKKS masih memiliki kadar abu yang tinggi sehingga biomassa hasil torefaksi belum sesuai untuk cofiring di pembangkit listrik atau sebagai bahan baku untuk gasifikasi.Kata kunci: Counter-Flow Multi Baffle; tandan kosong kelapa sawit; terbarukan; torefaksi

Sugarcane bagasse, the solid waste material produced in the sugar industry, was subjected to treatment in hot compressed water. The experiments were performed in a batch-type reactor containing slurry of 10 ml of water and 1.2 g of solids. The reactor was heated to temperatures ranging between 200 • C and 300 • C for reaction times of 3 to 30 min. The product was separated into liquid and solid fractions. Each fraction was analyzed to investigate the alteration of the main lignocellulosic polymers by hot compressed water. Results for the liquid fractions showed that increased temperatures and reaction times completely dissolved hemicellulose and cellulose in the water, leaving lignin in the solid product. During treatment, hemicellulose and cellulose gradually decomposed into simple sugars, which were then degraded and decomposed into furfural, 5-(hydroxymethyl)furfural (5-HMF) and organic acids. However, the yield of furans and some organic acids decreased and became undetectable at 300 • C and with increasing reaction time. The solid fraction was also characterized before and after treatment. Results showed that the hydrogen and oxygen content of the solids decreased with increased reaction conditions, due to dehydration and decarboxylation reactions. The reactions also increased the carbon content of the treatment products by 1.2-1.6 times that in the raw material, suggesting that the hot compressed water treatment of sugarcane bagasse can be considered for the provision of valuable chemicals for biofuel and high-carbon-content material (biochar).