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30 1.8 7.0 12.3 17.5
50 1.1 4.3 7.6 10.8
70 0.8 3.3 5.8 8.2
1 Two or three harvesters required
7.5 Conclusion and Recommendations
A desktop assessment of mallee harvest haul logistics has been undertaken for Western Australian
alley plantings. The modelling was based on the approach widely used in the sugar industry (Sandell
and Prestwich, 2004).
The analysis indicates that harvester pour rate has the largest impact on the cost of harvest. High pour
rates equate to more income for each unit of fuel, wages and all other costs.
Tonnes harvested per season also have a large effect on the cost of harvest. Higher annual tonnes
equate to better capital utilisation.
Road haul distance has the next largest effect on cost of harvest: - the further the wood chip is carted,
the more it costs. With haul distances of 100km haulage costs are likely to be around $15/green
tonne.
Capital cost has some impact on the cost of harvest but is less critical. The selection of capital
equipment is important as it can bring inherent efficiencies. It is also important that in-field
equipment be suited to the adverse conditions found in mallee harvesting.
Row spacing has a small impact on the cost of harvest because the harvester spends most of the time
harvesting due to relatively low ground speeds and large row lengths.
For small scale industry development (14,400 green tonnes/yr of biomass chip delivery which is
equivalent to a 2MW power generation capacity) and current prototype harvester performance (30
green tonnes/hr pour rate) harvesting costs are shown to be around $29.60/green tonne. Combined
with road haulage costs of $15/green tonne this would equate to a delivered cost to a processor of
$44.6/green tonne. To this one would need to add a return to the grower (stumpage cost). This needs
to be compared against the value of product to the processor and the fee the processor is prepared to
pay. A harvester would be underutilised under this scenario.
For large scale industry development (144,000 green tonnes/yr of wood chip delivery which is
equivalent to a 20MW power generation capacity) and future harvester performance (50t/hr pour rate)
harvesting costs are shown to be around $13.50/green tonne. Combined with road haulage costs of
$15/green tonne this would equate to a delivered cost to a processor of $28.50/green tonne. This
would provide a more appropriate cost of supply when compared with the fee the processor is likely to
be prepared to pay. A harvester would be required to work an average 11 hours per day to process this
tonnage.
Table 7.7 compares likely harvesting costs of alley based mallee systems in Western Australia to
whole crop sugar systems in NSW. Sugarcane systems have a much lower harvesting cost
($6.40/green tonne) based on the large scale of the industry (good capital utilisation), high crop yields
(170t/ha) and high delivery rates. Despite higher harvester field efficiency rates under mallee systems
(owing to the large proportion of time spent cutting in the row) the delivery rate to the road haulage
vehicle is relatively low. This results in a high harvest cost which is approximately twice that for
170