What Factors Influence Charcoal Quality?
100C -> Wood drying 19 MJ/kg
220C -> Wood becomes brown
250-270C-> Torrefaction 28% fixed carbon, 72% volatile 23.9 MJ/kg
280C -> Wood becomes deep brown-black
300C -> 68% char 32% volatile 40% yield soft, brown, friable
400C FAO ->the process stops and the temperature reaches a maximum of about 400°C. This charcoal, however, will still contain appreciable amounts of tarry residue, together with the ash of the original wood. The ash content of the charcoal is about 3-5%; the tarry residue may amount to about 30% by weight and the balance is fixed carbon about 65-70%.
400-450C -> 80% char 20% volatile
500C- > 86% char 13% volatile, 33% yield 32 MJ/kg
700C -> 93% char 7% volatile 30% yield hard and brittle
FAO: Low carbonization temperatures give a higher yield of charcoal but this charcoal is low grade, is corrosive due to its content of acidic tars, and does not burn with a clean smoke-free flame. Good commercial charcoal should have a fixed carbon content of about 75% and this calls for a final carbonising temperature of around 500°C.
FAO Simple technologies for Charcoal Making #41 Rome 1987 M-37 ISBN 92-5-101328-1
FAO Chapter 4 Carbonization Processes
FAP Chapter 10 Using Charcoal Efficiently
10.1 The Quality of Charcoal
10.1.5 Typical Charcoal Analyses
10.2 Burning Charcoal Efficiently
Introduction to Bamboo Charcoal China
Bamboo Charcoal StandardAnnex 1
Hibajene, S. H. 1994. Assessment of Earth Kiln Charcoal Production Technology Zambia, SEI EE&D 39 p. ISBN: 91-88714-01-2.
Evaluation of Woody Biomass Torrefaction Jingge Li and John Gifford Forest Research, Rotorua, New Zealand September 2001
Testing of Barbecue Coal and Barbeque Coal Briquettes Force Technology, Denmark.
A Social and Technical Analysis of Charcoal Production in the Narok District of Kenya RAEL
Industrial Charcoal Production" Appendix B Sustainable Steelmaking Using Renewable Forest Energy NSW Sustainable Energy Research and Development Fund (SERDF)
Effect of Final Pyrolysis Temperature on Charcoal Yield Table 2. Cookstove.net
>From the Phyllis database
Reed and Guar (ID 1954): 34390 kJ/kg at 1% ash and 9.4% volatiles.
Gliricida, Nigeria (ID 2118): 33100 kJ/kg at 2.2% ash and 48% volatiles
Oak Wood, Antal, flash carbonization: 31600 kJ/kg 20% volatile, 0.5% ash
Pine, Di Blasi, (ID1725): 31107 kJ/kg 0.3% ash
Eucalyptus, Reed and Guar (ID1956): 27600 kJ/kg,
10.4% ash. 19.2% volatiles
Casuarina, Reed and Guar (ID 1953): 27120 kJ/kg 13.2% ash and 15.2%
Willow char ECN (ID 2716): 26700 kJ/kg 4.1% ash, 34.4% volatile.
Charcoal, EPA India (600R00052AppF), LHV (NCV) 25715 at 7.4% ash
Char Briquette , EPA India (600R00052AppF), LHV (NCV) 15298 at 40% ash
Oak, Reed and Guar (ID 1958): 24800 kJ/kg 14.9% ash and 25.8% volatile
Oak, Reed and Guar (ID 1957) 23050 kJ/kg 17.3% ash and 27.1% volatiles.
Char, ECN measured (ID 2111): 20120 kJ/kg with 20.9% ash and 32.3%
SNV Nepal S. Nienhuy Beehive Briquette Stove; Charcoal mixed with clay = 18 MJ/kg.
Tom Reed Nov 29 2001:
"Cooking charcoal typically retains 20% of the volatiles and is more like 24
kJ/g. (Other species along the pyrolysis
trail are: torrefied wood (240-280C) ~23 kJ/g; Sea Sweep, our oil
absorbent. . .at 350C, higher; then cooking charcoal ~25
kJ/g; metallurgical charcoal, ~ 600 C; activated charcoal, ~800 C with
steam, CO2 or chemicals."