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2010). Table 4.2 presents a summary of some potential products, and an assessment of the parameters
above.
Table 4.2 indicates that a large scale Mallee Industry would potentially very significantly impact on
the current value of a number of products. For example, current producers of eucalyptus oil would see
a dramatic reduction in the value of their product if even a small percentage of the potential
production of mallee oil entered the market they are currently targeting. As part of an industrial
process however, even at the anticipated dramatically reduced oil value, oil extraction could be an
important component of overall economics of a larger industry.
Other high value markets are generally low product volume, such as thermal energy displacement in
local industries such as feedmills and abattoirs, and the even smaller potential market as local
electricity production utilising rapidly developing technologies such as Organic Rankine Cycle
systems to convert low grade thermal energy to electricity to displace diesel electricity generation
units.
Potential higher value uses without volume limitations include conversion utilising gasification or
pyrolysis to liquid fuels. Current technology converts the syngas and other gaseous products to heavy
oil, which can be utilised directly as a furnace fuel, or refined into more traditional products. More
recent development has been towards “reforming” the gas products over a catalyst to produce
synthetic diesel or avgas, and limited by-products. Whilst substantial research and development is
being undertaken into this technology and results are exciting, it is not yet commercialised.
Indications are that overall conversion efficiency is in the order of 55%, although higher efficiencies
are potentially achievable (Holmgren pers com, 2011). Charcoal and combustible gasses are
additional products.
Table 4.3- 4.9 analyses each potential product, including anticipated industrial product value, and
extraction/conversion costs to derive values for the crop component being utilised as feedstock for a
process.
4.4.1 Mallee oil
Available data indicates that average oil recovery from steam extraction is approximately 10 kg/green
tonne from whole trees or 18 kg/green tonne from leaf and twig components. This is nominally
consistent with minimal extractable oil in the wood component of the tree, and varies according to
leaf age, season and other agronomic parameters. The energy required for steam extraction of the oil
is typically 10 kg of saturated steam/kg of oil, however allowance must also be made for heating of
the biomass prior to extraction commencing.
The extraction process results in a leeching of much of the water-soluble alkali products from the leaf.
The resulting liquor has some potential value as a fertiliser because of this, however energy would be
required to concentrate it to reduce the product volume for cost efficient transport. More significantly,
research indicates that the oil extraction process can actually increase the value of these components
for some downstream uses such as metallurgical charcoal. The process would also be anticipated to
increase the value of these products for various thermal uses because of the reduction in specific
alkalis.
After the extraction process, the leaf and twig material would have to be dried before further use. The
use of thermal drying utilising a proportion of the material after oil extraction would consume in the
order of 35% of the product. Alternative strategies include solar drying, by spreading the product in
thin layers over a large area. This would involve a number of operations and cost to spread, turn and
collect the material.
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