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Mallee system
Most of the mallee biomass appears to be destined for use as an energy resource. Energy is a
commodity required, at one extreme, continuously 365 days a year, through to about 2,000 hours a
year, for example during the daylight operations of a rural business operating a small boiler for
process heat. There will be no seasonal demand for the energy.
The benefit of biomass as a primary fuel source is that, with appropriate storage and handling
systems, it is easy to stockpile. However the difference between efficient and appropriate on one hand
and dysfunctional and unaffordable stockpiling on the other depends upon the details of handling a
relatively complex product. Wood chip handling is significantly different from handling whole-tree
biomass, because the whole-tree material contains long pieces from the top of the branches. Some
form of screening and upgrading is essential, and it may even be justified to convert the biomass to
fuel pellets, because the high cost of pellet manufacture may be more than recovered by efficiency in
fuel handling and boiler management further along the supply chain.
To cover for times when field operations are interrupted, it will be essential to stockpile biomass at
some point along the supply chain. Interruptions may occur due to seasonal factors including unstable
soils in wet seasons, mallee regeneration problems when harvesting sites where soil moisture is
exhausted and the mallees are under moisture stress, or vehicle movement bans during days of high
fire risk. Before stockpiling, the minimum level of processing required will be:
• Screening to remove oversize particles that are inevitable when chipping, and especially
when chipping whole trees. Overs should be re-chipped back onto the screen to avoid the
accumulation of a waste material that is difficult to handle and has no value.
• Separation of the wood from the rest of the biomass, because wood chip and the mixture of
leaf, bark and fines will dry out and store differently.
Clean wood chip can be stockpiled green. The leaf, bark and fines mixture will need to be dried
before stockpiling, and this may be easier if the eucalyptus oil is distilled from the green mass
Sugar system
Seasonal supply volumes are determined using a combination of methods. Determining mill opening
and closing date and the length of milling season (typically around 20 weeks) is critical to ensure
optimum use of crushing and processing capacity and to target the optimal harvesting window, which
captures peak sucrose and cane quality. Stockpiling of cane as a buffer is not possible owing to
deterioration of quality and harvest to crush delays of less than 12 hours are required.
Long term historical data from cane supply and associated quality records are available on a field by
field basis and are used to determine anticipated seasonal supply volumes. Sugarcane crop production
modeling has also been used in the industry to forecast seasonal supply volumes based on prevailing
and future weather scenarios. Satellite imagery is also used in some cases to assess infield crop
variability, area under sugarcane and incremental proportion of the supply area harvested as the
season progresses. This provides a sound basis for estimating remaining area to be harvested and
volume of cane to be delivered.
Information on tonnes cane delivered from each block of land is available from records of bin weight
at the weighbridge. Each delivery bin can be referenced by RFID tag to the field of harvest and each
harvester can be tracked by GPS to monitor, on a daily basis, the area harvested and delivery area
supplying each bin. These systems allow users to manage the production and harvest progress and
interpret remaining harvest areas and remaining supply volumes for the season. Section 6.5 of this
report provides further detail on these methods.
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