Improving Thermochemical and Physical Properties of Cocoa Pod Shell by Torrefaction and its Potential Utilization

Untoro Budi Surono, Harwin Saptoadi, Tri Agung Rohmat


Torrefaction process is one of the solutions to produce solid fuel from a cocoa pod shell (CPS). Fuel characteristics of CPS changed after torrefaction. Effects of torrefaction temperature and holding time on physical, thermal, and chemical properties of CPS were investigated in this study. The experiments were conducted in a tubular torrefaction reactor. Three different torrefaction temperatures of 200, 250, and 300°C and four holding times of 0, 30, 60, and 90 min were considered in this investigation. It was found that the color of CPS changed from light brown to black due to the increasing content of fixed carbon and depend on the torrefaction temperature and the holding time. The decrease in the grayscale value of the torrefied CPS represented an increase in HHV. Fixed carbon content and - higher heating value (HHV) of the torrefied CPS increased up to 17.5% and 41.3% compared to the raw CPS, while the volatile matter decreased up to 19.4%. The O/C and H/C atomic ratio decreased from 0.79 and 1.68 to 0.37 and 1.01, respectively, which corresponded to the increase of carbon content and decrease of oxygen and hydrogen contents. The properties of severe torrefaction CPS resembled between lignite and peat. The grindability and hydrophobicity of CPS was improved. The CPS based biochar should be used as a substitute for solid fuel that has the same characteristic to reduce the unfavorable effects of its potassium content.


cocoa pod shell (CPS); grindability; higher heating value; hydrophobicity; torrefaction

Full Text:



Tekin K., Karagöz S., Bekta S., 2014. A review of hydrothermal biomass processing. Renewable and Sustainable Energy Review 40, 673–687. doi:10.1016/j.rser.2014.07.216.

Yang Z., Sarkar M., Kumar A., Tumuluru J.S., and Huhnke R.L., 2014. Effects of torrefaction and densification on switchgrass pyrolysis products. Bioresource Technology 174, 266–273. doi:10.1016/j.biortech.2014.10.032.

Pimchuai A., Dutta A., and Basu P., 2010. Torrefaction of agriculture residue to enhance combustible properties. Energy Fuel 24: 4638–4645. doi:10.1021/ef901168f.

Arteaga-Pérez L.E., Segura C., Espinoza D., Radovic L.R., and Jiménez R., 2015. Torrefaction of Pinus radiata and Eucalyptus globulus: A combined experimental and modeling approach to process synthesis. Energy for Sustainaible Development 29: 13–23. doi:10.1016/j.esd.2015.08.004.

Basu P., 2013. Biomass Gasification, Pyrolysis and Torrefaction (Practical Design and Theory), 2nd edition. New York: Academic Press.

Bergman P.C.A., 2005. Combined torrefaction and pelletisation, the TOP process (Report No. ECN-C-05-073). The Netherlands: Energy Research Center of The Netherlands (ECN).

Bridgeman T.G. and J.M. Jones. 2008. Torrefaction of reed canary grass, wheat straw and willow to enhance solid fuel qualities and combustion properties. Fuel 87: 844–856. doi:10.1016/j.fuel.2007.05.041.

Bach Q. and Ø. Skreiberg. 2016. Upgrading biomass fuels via wet torrefaction : A review and comparison with dry torrefaction. Renewewable and Sustainable Energy Reviews 54, 665–677. doi:10.1016/j.rser.2015.10.014.

Anggono W., Suprianto F.D., Evander J., and Gotama G.J., 2018. Biomass briquette investigation from pterocarpus indicus twigs waste as an alternative renewable energy. International Journal on Renewable Energy Resources 8, 10–12.

ICCO, 2017. Quarterly Bulletin of Cocoa Statistics. Volume XLIII, No. 1. Cote d’Ivoire: International Cocoa Organization (ICCO).

DGEC, 2017. The Estate Crop Statistics of Indonesia 2015-2017. Jakarta: Directorate General of Estate Crops (DGEC).

Nguyen V.T.. 2015. Mass proportion, proximate composition and effects of solvents and extraction parameters on pigment yield from cacao pod shell (theobroma cacao l.). Journal of Food Processing and Preservation 39: 1414–1420. doi:10.1111/jfpp.12360.

Adzimah S.K. and E.K. Asiam. 2010. Design of a Cocoa Pod Splitting Machine. Research Journal of Applied Science Engineering and Technology 2: 622–634.

Kai X., Meng Y., Yang T., Li B., and Xing W. 2019. Effect of torrefaction on rice straw physicochemical characteristics and particulate matter emission behavior during combustion. Bioresource Technology 278, 1–8. doi:10.1016/j.biortech.2019.01.032.

Cai W., Fivga A., Kaario O., and Liu R., 2017. Effects of torrefaction on the physicochemical characteristics of sawdust and rice husk and their pyrolysis behavior by thermogravimetric analysis and pyrolysis − gas chromatography / mass spectrometry. Energy and Fuel 31: 1544–1554. doi:10.1021/acs.energyfuels.6b01846.

Mei Y., Che Q., Yang Q., Draper C., Yang H., Zhang S., and Chen H., 2016. Torrefaction of different parts from a corn stalk and its effect on the characterization of products. Industrial Crops and Products 92: 26–33. doi:10.1016/j.indcrop.2016.07.021.

Liu S., Tsai W., and Li M., 2015. Effect of holding time on fuel properties of biochars prepared from the torrefaction of coffee residue. Biomass Conversion and Biorefinery 5: 209–214. doi:10.1007/s13399-014-0139-1.

Liu Z. and G. Han. 2015. Production of solid fuel biochar from waste biomass by low temperature pyrolysis. Fuel 158: 159–165. doi:10.1016/j.fuel.2015.05.032.

Chiou B., Valenzuela-medina D., Bilbao-sainz C., Klamczynski A.K., Avena-bustillos R.J., Milczarek R.R., Du W., Glenn G.M., and Orts W.J., 2015. Torrefaction of pomaces and nut shells. Bioresource Technology 177, 58–65. doi:10.1016/j.biortech.2014.11.071.

Shang L., Ahrenfeldt J., Kai J., Sanadi A.R., Barsberg S., Thomsen T., Stelte W., and Henriksen U.B., 2012. Changes of chemical and mechanical behavior of torrefied wheat straw. Biomass and Bioenergy 40: 63–70. doi:10.1016/j.biombioe.2012.01.049.

Syamsiro M., Saptoadi H., Tambunan B.H., and Pambudi N.A., 2012. A preliminary study on use of cocoa pod husk as a renewable source of energy in Indonesia. Energy for Sustainaible Development 16: 74–77. doi:10.1016/j.esd.2011.10.005.

Forero-Nuñez C.A., Jochum J., and Sierra F.E., 2015. Effect of particle size and addition of cocoa pod husk on the properties of sawdust and coal pellets. Ingeniería e Investigación 35: 17–23.

Kumar T. and K. Verma. 2010. A Theory based on conversion of RGB image to gray image. International Journal of Computer Applications 7: 5–12. doi:10.5120/1140-1493.

Güneş A., Kalkan H., and Durmuş E., 2016. Optimizing the color-to-grayscale conversion for image classification. Signal, Image Video Processing 10, 853–860. doi:10.1007/s11760-015-0828-7.

Medic D., Darr M., Shah A., and Rahn S., 2012. Effect of torrefaction on water vapor adsorption properties and resistance to microbial degradation of corn stover. Energy Fuels 26(4): 2386-2393.

Uemura Y., Omar W.N., Tsutsui T., and Bt S., 2011. Torrefaction of oil palm wastes. Fuel 90: 2585–2591. doi:10.1016/j.fuel.2011.03.021.

Gucho E.M., Shahzad K., Bramer E.A., and Akhtar N.A., 2015. Experimental study on dry torrefaction of beech wood. Energies 8: 3903–3923. doi:10.3390/en8053903.

Saito Y., Sakuragi K., Shoji T., and Otaka M., 2018. Expedient prediction of the fuel properties of carbonized woody biomass based on hue angle. Energies 11: 1–8. doi:10.3390/en11051191.

Acharya B. and A. Dutta. 2016. Fuel property enhancement of lignocellulosic and nonlignocellulosic biomass through torrefaction. Biomass Conversion and Biorefinery 6: 139–149. doi:10.1007/s13399-015-0170-x.

Thanapal S.S., Annamalai K., Ansley R.J., and Ranjan D., 2016. Co-firing carbon dioxide-torrefied woody biomass with coal on emission characteristics. Biomass Conversion and Biorefinery 6: 91–104. doi:10.1007/s13399-015-0166-6.

Correia R., Gonçalves M., Nobre C., and Mendes B., 2017. Impact of torrefaction and low-temperature carbonization on the properties of biomass wastes from Arundo donax L . and Phoenix canariensis. Bioresource Technology 223: 210–218. doi:10.1016/j.biortech.2016.10.046.

Wilk M., Magdziarz A., and Kalemba I., 2015. Characterisation of renewable fuels ’ torrefaction process with different instrumental techniques. Energy 87: 259–269. doi:10.1016/

Uemura Y., Matsumoto R., Saadon S., and Matsumura Y., 2015. A study on torrefaction of Laminaria japonica. Fuel Processing Technology 138: 133–138. doi:10.1016/j.fuproc.2015.05.016.

Wannapeera J., Fungtammasan B., and Worasuwannarak N., 2011. Effects of temperature and holding time during torrefaction on the pyrolysis behaviors of woody biomass. Journal of Analytical and Applied Pyrolysis 92: 99–105. doi:10.1016/j.jaap.2011.04.010.

Odusote J.K., Adeleke A.A., Lasode O.A., Malathi M., and Paswan D., 2019. Thermal and compositional properties of treated Tectona grandis. Biomass Conversion and Biorefinery 1–9. doi:10.1007/s13399-019-00398-1.

Supramono D., Devina Y.M., and Tristantini D., 2015. Effect of heating rate of torrefaction of sugarcane bagasse. International Journal of Technology 7: 1084–1093.

Li M., Li X., Bian J., Chen C., Yu Y., and Sun R., 2015. Effect of temperature and holding time on bamboo torrefaction. Biomass and Bioenergy 83: 366–372. doi:10.1016/j.biombioe.2015.10.016.

Chen Y., Liu B., Yang H., Yang Q., and Chen H., 2014. Evolution of functional groups and pore structure during cotton and corn stalks torrefaction and its correlation with hydrophobicity. Fuel 137: 41–49. doi:10.1016/j.fuel.2014.07.036.

Tumuluru J.S., Sokhansanj S., Hess J.R. and Wright C.T., and Boardman R.D., 2011. A review on biomass torrefaction process and product properties for energy applications. Industrial Biotechnology 7(5): 384–401. doi:10.1089/ind.2011.0014.

Bridgeman T.G., Jones J.M., Williams A., and Waldron D.J., 2010. An investigation of the grindability of two torrefied energy crops. Fuel 89: 3911–3918. doi:10.1016/j.fuel.2010.06.043.

Asadullah M., Adi A.M., Suhada N., Malek N.H., Saringat M.I., and Azdarpour A., 2014. Optimization of palm kernel shell torrefaction to produce energy densified bio-coal. Energy Conversion and Management 88: 1086–1093. doi:10.1016/j.enconman.2014.04.071.

Iroba K.L., Baik O., and Tabil L.G., 2017. Torrefaction of biomass from municipal solid waste fractions I : Temperature profiles, moisture content, energy consumption, mass yield, and thermochemical properties. Biomass and Bioenergy 105: 320–330. doi:10.1016/j.biombioe.2017.07.009.

Wang L., Barta-rajnai E., Skreiberg Ø., Khalil R., Czégény Z., Jakab E., Barta Z., and Grønli M., 2017. Effect of torrefaction on physiochemical characteristics and grindability of stem wood, stump and bark. Applied Energy doi:10.1016/j.apenergy.2017.07.024.

Chen W., Hsu H., Lu K., Lee W., and Lin T., 2011. Thermal pretreatment of wood (Lauan) block by torrefaction and its influence on the properties of the biomass. Energy 36: 3012–3021. doi:10.1016/

Arias B., Pevida C., Fermoso J., Plaza M.G., Rubiera F., and Pis J.J., 2008. Influence of torrefaction on the grindability and reactivity of woody biomass. Fuel Processing Technology 89: 169–175. doi:10.1016/j.fuproc.2007.09.002.

Gou X., Zhao X., Singh S., and Qiao D., 2019. Tri-pyrolysis: A thermo-kinetic characterisation of polyethylene, cornstalk, and anthracite coal using TGA-FTIR analysis. Fuel 252: 393–402. doi:10.1016/j.fuel.2019.03.143.

Chen X., Liu L., Zhang L., Zhao Y., and Qiu P., 2019. Gasification reactivity of co-pyrolysis char from coal blended with corn stalks. Bioresource Technology 279, 243–251. doi:10.1016/j.biortech.2019.01.108.

Zhang K., Li Y., Wang Z., Li Q., Whiddon R., He Y., and Cen K., 2016. Pyrolysis behavior of a typical Chinese sub-bituminous Zhundong coal from moderate to high temperatures. Fuel 185: 701–708. doi:10.1016/j.fuel.2016.08.038.

Amirabedin E., Pooyanfar M., Rahim M.A., and Topal H., 2014. Techno-environmental assessment of co-gasification of low-grade Turkish lignite with biomass in a trigeneration power plant. Environmental and Climate Technologies 13: 5–11. doi:10.2478/rtuect-2014-0001.

Mursito A.T., Hirajima T., and Sasaki K., 2010. Upgrading and dewatering of raw tropical peat by hydrothermal treatment. Fuel 89: 635–641. doi:10.1016/j.fuel.2009.07.004.

Tsai C., Tsai W., Liu S., and Lin Y., 2008. Thermochemical characterization of biochar from cocoa pod husk prepared at low pyrolysis temperature. Biomass Conversion and Biorefinery 8: 237–243. doi:10.1007/s13399-017-0259-5.

Martínez-Ángel J.D., Villamizar-Gallardo R.A., and Ortíz-Rodríguez O.O., 2015. Characterization and evaluation of cocoa (Theobroma cacao L.) pod husk as a renewable energy source. Agrociencia. 49: 329–345.