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2.3.5 Fuel consumption
Sugar System
Typically, harvester fuel usage is expressed as fuel used, divided by the total tonnes cut over an
extended period. A potentially more useful approach is to calculate fuel efficiency as the harvester
operates. However, simple calculations of estimated operating fuel consumption versus pour rate
result in very low fuel usage figures per tonne harvested, which the industry would consider
nonsensically low. The discrepancy is primarily because of the percentage of time the engine is
operating but the harvester is not actually processing cane, e.g. when turning at ends of rows, waiting
for haulouts with the engine operating etc.
The engine size of harvesters has increased from about 240 Hp (176 kW) in the early 1990’s up to
375 Hp (275 kW) in today’s models.
The high power availability and hence high fuel usage demand high productivity. This translates into
high machine pour rates. In addition, high parasitic losses (e.g. cooling losses, component no load
power consumption) reduce overall machine efficiency. Improved machine component-crop
interaction (e.g. improved feeding) and minimising weight can reduce the need for high power
requirements.
The field efficiency or the time sugarcane harvesters are actually processing cane is about 50% of the
engine operating hours. Further data on field efficiency is can be found in Section 2.4.3
When turning at ends of rows or for short waits for haulouts, operators typically maintain the engine
at full power setting, and throttle back for extended periods when waiting for bins etc. Clearly,
factors such as row length, haulout waiting time and a range of external factors dramatically impact
on fuel consumption/tonne harvested.
Instantaneous fuel consumption allows realistic estimates of relative fuel consumption as key factors
such as harvesting mode (burnt, green, shredding and whole-crop) crop size and pour rates change.
Willcox et al. (2004) measured the average harvester fuel usage under green cane and burnt cane
conditions in the Maryborough, Mackay and Ingham regions in Queensland over a two year period.
They measured total fuel used per day and divided it by the total tonnes cut for the day. Table 2.5
shows the effect of crop yield on harvester fuel usage for green and burnt cane conditions. Harvesting
crops green consume about 40% more fuel per tonne than harvesting burnt cane due to material
processing and cleaning.
Whole-of-crop harvesting fuel consumption estimates are about 15-20% higher than required for
burnt cane. The increased power to the choppers and basecutters is compensated for by the reduced
power for the extractors (Norris et al. 2000).
NSWSMC has measured fuel usage of 0.89 L/tonne to 1.19 L/tonne in NSW two-year-old crops (M
Inderbitzin pers com 2010).
Table 2.5 Effect of yield on harvester fuel use (Willcox 2004)
Crop Size Fuel use Fuel Use
T/Ha Green Cane Burnt Cane
53