Multi-objective operation optimization of spent coffee ground torrefaction for carbon-neutral biochar production

Chen WH 1 , Lee KT 2 , Ho KY 2 , Culaba AB 3 , Ashokkumar V 4 , Juan CJ 5

Affiliations 

  • 1 Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan. Electronic address: weihsinchen@gmail.com
  • 2 Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan
  • 3 Department of Mechanical Engineering, De La Salle University, 2401 Taft Avenue, 0922 Manila, Philippines; Center for Engineering Sustainable Development Research, De La Salle University, 2401 Taft Avenue, 0922 Manila, Philippines
  • 4 Biorefineries for Biofuels & Bioproducts Laboratory (BBBL), Center for Trandisciplinary Research, Department of Pharmacology, SDC, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai 600077, India
  • 5 Nanotechnology & Catalysis Research Centre (NanoCat), Institute of Postgraduate Studies, University Malaya, 50603 Kuala Lumpur, Malaysia
Bioresour Technol, 2023 Feb;370:128584.
PMID: 36610482 DOI: 10.1016/j.biortech.2023.128584

Abstract

Many energy-intensive processes are employed to enhance biomass fuel properties to overcome the difficulties in utilizing biomass as fuel. Therefore, energy conservation during these processes is crucial for realizing a circular bioeconomy. This study develops a newly devised method to evaluate SCG biochars' higher heating value (HHV) and predict moisture content from power consumption. It is found that the increasing rates of HHV immediately follow decreases in power consumption, which could be used to determine the pretreatment time for energy conservation. The non-dominated sorting genetic algorithm II (NSGA-II) maximizes SCG biochar's HHV while minimizing energy consumption. The results show that producing SCG biochar with 23.98 MJ∙kg-1 HHV requires 20.042 MJ∙kg-1, using a torrefaction temperature of 244 °C and torrefaction time of 27 min and 43 sec. Every kilogram of biochar with an energy yield of 85.93 % is estimated to cost NT$ 12.21.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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