Civil Engineering Reference
In-Depth Information
Test runs were then done with the calculator, and the results were plotted
to establish a relationship between the size of the station and its cost. A linear
trendline was then fitted to these lines, and equations were derived to represent
the best relationship between a station's size and cost. The trendlines are
shown in Figure 1, and their matching equations were entered in the VICE
model to derive station cost.
It should be noted that the school station is less expensive for the practical
range of a school fleet, yet its costs rise at a steeper rate than the others
because it uses equipment that cannot be scaled up as efficiently. The school
station is only charted up to 65,000 DGEs per month because school fleets use
less fuel, so no scenarios were modeled that involved a school fleet using more
than this amount of fuel. Refuse stations achieve greater economies of scale
than transit stations—presumably because their larger refueling window
allows for greater increase of throughput without a corresponding increase in
equipment.
Figure 1. The relationship between the size of a CNG station and its cost. It should be
noted that the upper end of the station throughput range (300,000 DGE) is uncommon.
Fleet Scenarios
The VICE model considers seven different fleets with the following
parameters:
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