This engineering study compares direct and indirect cassava-rhizome pyrolysis in an integrated fixed-bed carboniser and cross-draft gasifier–burner, measuring time, fuel, product yields, biochar quality, pyroligneous acid and greenhouse-gas emissions.
Key findings
- Direct heating reduced time from 370 to 240 minutes and firewood from 56 to 15 kg, raising biochar productivity from 1.13 to 2.82 kg/h while yield remained 24.3–25.0%. Pyroligneous acid rose from 34.8% to 43.8%, specific emissions fell from 9.19 to 2.85 kg CO₂-eq/kg biochar, and carbon content was 76.01–77.00%.
Why this matters globally
The system could valorise cassava residues and reduce fuel demand at community scale, but net climate benefit depends on feedstock logistics, coproduct use and long-term carbon storage.
Thai researcher contribution
Nathawat Unsomsri, Songkran Wiriyasart and corresponding author Sommas Kaewluan of Srinakharinwirot University developed and tested the system using a major Thai biomass residue.
Limitations to consider
This is a configuration-specific comparison; replication and emissions uncertainty require full-text review. The boundary may not be a full life-cycle assessment. Ash exceeded cooking-charcoal requirements, and cost, durability, fine pollutants and soil performance were not tested.