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Table 4.5 Value of feedstock components for Metallurgical Charcoal
Product Value ($/t)
Component Used
Extraction cost ($/t)
$198 high volume sales
Woodchip / log and “extracted” leaf and twig
$50/t charcoal
Product Value ($/t) $148.00
Product yield (% of freshweight) 20-30%
Value/gt freshweight separated woodchip/log $ 36.00-$54.00
Value/gt freshweight whole tree including extracted leaf $ 36.00-$54.00
Residual and co-products
Co-Product value
Heat & syngas/ bio-crude.
App 60% of initial energy content as heat and
combustables/feedstock.
As with the production of activated charcoal, the production of metallurgical charcoal results in
significant heat production and production of syngas. Whilst a greater proportion of the initial energy
is lost to the charcoal product stream, significant energy is still available for downstream use as heat
or for the production of bio-crude.
4.3.4 Bio-Char
Bio-char is a relatively newly commercialised product, with a range of uses. Bio-char has high value
use as a fertiliser component, whilst a lower value use is as a soil physical ameliorant. Biochar can
also be used as a vehicle for carbon sequestration, and a value can be derived based on the value
assumed for a carbon tax of nominally $50/tonne CO 2 .
As with other thermal conversion processes, the recovery of bio-char is dependent on the time and
temperature in the reactor, with low temperatures preferred for maximising char recoveries, with
overall recoveries of approximately 30% (char : freshweight) being reported as typical. The process
consumes the syngases and bio-crude, however the combustion of these products maximises the
exothermic nature of the reaction.
These lower temperature processes reduce the potential for efficient use of the liberated heat in
“steam cycle” conversion processes, however the exhaust heat temperature matches some processes
such as Organic Rankine Cycle units for electricity production.
Bio-Char as an industrial feedstock for the fertiliser industry has a very significantly higher value than
for its use for carbon sequestration, however the value as an industrial product will be dependent on
supply. The current price is in the order of $500/tonne (J Joyce, Pers Com, 2011). For this application,
pre-extraction of oil from leaf material would reduce its value because of the value of alkalis and
other inorganics in the leaf material when used as a fertiliser component.
Syngas and heat are by-products of the production of bio-char production, and these can be used
directly in downstream processes, e.g thermal applications.
Table 4.6 Value of feedstock components for Bio-Char for various uses.
Bio Char Fertiliser Additive CO 2 Sequestration
Product Value ($/t) $ 500 $50/t CO 2
Component Used whole tree whole tree
Extraction cost ($/t) $25 $25
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