Assessment of the use of biochar from the slow pyrolysis of walnut and almond shells as an energy carrier

Anabel Fernandez, Daniela Zalazar-García, Erick Torres, Rodrigo Torres-Sciancalepore, Prakash Parthasarathy, Gordon McKay, Gastón Fouga, Germán Mazza*, Rosa Rodriguez*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This study explores the energy applications and combustion kinetics of biochar produced from walnut and almond shells through pyrolysis. Using macro-thermogravimetric analysis at heating rates of 10, 15, and 20 K min−1, a multi-step mechanism involving two parallel reactions was used to model thermal decomposition. Bioenergy indices revealed that walnut shell-based biochar (WSB) produced at 773 K and 873 K displayed superior biofuel potential due to its high energy density and low ash content, while almond shell-based biochar (ASB) at 673 K demonstrated the best overall bioenergy performance. Among the tested heating rates, 15 K min−1 provided optimal results for ignition, combustion, and burnout indices, with WSB showing the highest overall combustion performance. Kinetic analysis using the Coats-Redfern method demonstrated the highest R2 values and minimized RMSE and SSE. The activation energy for the first pseudo-component ranged from 54.91 to 129.84 kJ mol−1 for ASB and from 61.71 to 141.85 kJ mol−1 for WSB. For the second pseudo-component, the activation energy ranged from 25.21 to 159.32 kJ mol−1 for ASB and 25.63 to 96.25 kJ mol−1 for WSB. These findings emphasize the potential of WSB and ASB biochar for bioenergy applications, with WSB exhibiting the best combustion characteristics.

Original languageEnglish
Pages (from-to)15379-15394
Number of pages16
JournalEnergy Sources, Part A: Recovery, Utilization and Environmental Effects
Volume46
Issue number1
DOIs
Publication statusPublished - 2024
Externally publishedYes

Keywords

  • Biochar
  • Biofuel properties
  • combustion performance
  • multi-step mechanism

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