Stratified downdraft gasification of wood chips with a significant bark content

Angelika Michaela Zachl*, Antonio Soria-Verdugo, Markus Buchmayr, Johann Gruber, Andres Anca-Couce, Robert Scharler, Christoph Hochenauer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The strict fuel quality limitations are amongst the main barriers preventing the success of small-scale downdraft gasification. In a first step towards alternative fuels, the application of wood chips with bark content must be investigated. Therefore, this paper presents the results of thermogravimetric analyses (TGA) and the gasification of wood chips with a significant larch bark content (up to 50%) in a stratified downdraft gasifier. The TGA revealed, that bark generated twice as much char as wood during pyrolysis. The gasification zones in the downdraft reactor did not shift when the fuel was switched, which allows its utilization in the same setup as pure wood chips. The concentrations of CO, H2 and CO2 were also almost unaffected at approximately 21.5 vol%, 14.6 vol% and 9.1 vol%, respectively. The highest gasification efficiency was achieved with 20% fuel bark content. The most significant effect was the reduction of the non-methane hydrocarbon content by up to 80% when bark was in the fuel, due to reduced tar generation and enhanced cracking. Therefore, the addition of bark up to a certain level even improved the gas quality and performance. These novel results predict a bright future for forestry residues in downdraft gasification.
Original languageEnglish
Article number125323
Issue numberB
Early online date1 Sept 2022
Publication statusPublished - 15 Dec 2022


  • Bark
  • Biomass downdraft gasification
  • Tar reduction
  • Thermogravimetric analysis
  • Wood chips

ASJC Scopus subject areas

  • Mechanical Engineering
  • Pollution
  • Energy Engineering and Power Technology
  • Energy(all)
  • Electrical and Electronic Engineering
  • Management, Monitoring, Policy and Law
  • Industrial and Manufacturing Engineering
  • Building and Construction
  • Fuel Technology
  • Renewable Energy, Sustainability and the Environment
  • Civil and Structural Engineering
  • Modelling and Simulation

Fields of Expertise

  • Sustainable Systems

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