19
could reduce revenues by as much as 0.6%. For trucks that are volume-limited ("cube out"), there
would be no such penalty.
would be no such penalty.
If idling uses 1 gal/h of diesel fuel and an alternative uses only 0.20 gal/h, at the current
price of about $1.75/gal, the immediate savings in operating cost is $1.40/h, for an annual dollar
savings equal to the number of idling hours avoided per year times 1.4. If there were no other
savings, a $6,000 unit would then have a 17-month payback time, if 3,000 hours of idling were
avoided per year. But fuel savings are not the only cost savings attributable to the reduction of
truck idling. Idling causes engine wear, and reducing idling allows an increase in the interval
between expensive oil changes and lengthens the actual mileage traveled before a truck engine is
likely to need an overhaul. The Truck Maintenance Council (TMC) published a bulletin to enable
estimation of the monetary value of these increases. Using the TMC's method, we estimate
approximately $0.07 savings on preventive maintenance (oil changes) and $0.07 savings by
increasing the time until overhaul, per hour of idling avoided. These savings are relatively small,
but not insignificant.
savings equal to the number of idling hours avoided per year times 1.4. If there were no other
savings, a $6,000 unit would then have a 17-month payback time, if 3,000 hours of idling were
avoided per year. But fuel savings are not the only cost savings attributable to the reduction of
truck idling. Idling causes engine wear, and reducing idling allows an increase in the interval
between expensive oil changes and lengthens the actual mileage traveled before a truck engine is
likely to need an overhaul. The Truck Maintenance Council (TMC) published a bulletin to enable
estimation of the monetary value of these increases. Using the TMC's method, we estimate
approximately $0.07 savings on preventive maintenance (oil changes) and $0.07 savings by
increasing the time until overhaul, per hour of idling avoided. These savings are relatively small,
but not insignificant.
4
The issue of payback time is an important consideration when examining equipment
purchases. The ATA (1997) has reported that truck owners are only interested in items with a
payback time of under two years. One reason for that is the rapid replacement rates in fleet
trucks. Because reliability is considered so critical, a typical small-fleet owner replaces his or her
trucks every three to four years, which is around the time when warranties expire. In addition, if
all trucks are under warranty, the fleet operation is simplified because the owner does not need a
complete maintenance shop. Larger fleets may be replaced even more often (every two to three
years); taking advantage of volume discounts offered by dealers. With such rapid fleet turnover,
factory-installed units, which are likely to be available at lower cost, could be a more promising
market than retrofits. Retrofits might be attractive for owner-operators who keep their trucks
longer, but small operators often follow larger ones in adoption of any innovation (Riemer 1999).
payback time of under two years. One reason for that is the rapid replacement rates in fleet
trucks. Because reliability is considered so critical, a typical small-fleet owner replaces his or her
trucks every three to four years, which is around the time when warranties expire. In addition, if
all trucks are under warranty, the fleet operation is simplified because the owner does not need a
complete maintenance shop. Larger fleets may be replaced even more often (every two to three
years); taking advantage of volume discounts offered by dealers. With such rapid fleet turnover,
factory-installed units, which are likely to be available at lower cost, could be a more promising
market than retrofits. Retrofits might be attractive for owner-operators who keep their trucks
longer, but small operators often follow larger ones in adoption of any innovation (Riemer 1999).
A simple economic analysis of several options to reduce truck idling is presented in Table 5,
with payback time estimated as a function of hours idled per year, on the basis of the expected
fuel costs for each unit. Savings from reduced maintenance and wear are included. Using this
table requires some caveats. First, as with the emissions data, some of the numbers are projected
because there is no real experience with these options. For instance, the cost for thermal storage
is a target that has not been achieved, and the electrification costs are quite uncertain. Second,
heaters and APUs from different manufacturers have different costs and energy requirements.
Third, the cost of additional fuel to operate the truck on the road if the thermal storage medium
must be heated or cooled has not been included because it is unknown. And finally, for the units
that supply heating only, the number of idling hours includes those occurring during the winter
fuel costs for each unit. Savings from reduced maintenance and wear are included. Using this
table requires some caveats. First, as with the emissions data, some of the numbers are projected
because there is no real experience with these options. For instance, the cost for thermal storage
is a target that has not been achieved, and the electrification costs are quite uncertain. Second,
heaters and APUs from different manufacturers have different costs and energy requirements.
Third, the cost of additional fuel to operate the truck on the road if the thermal storage medium
must be heated or cooled has not been included because it is unknown. And finally, for the units
that supply heating only, the number of idling hours includes those occurring during the winter
4
Note that previous estimates of maintenance savings were considerably higher. The difference is in the
number of miles to which one hour of idling is equivalent. The TMC bulletin assesses engine wear
proportional to fuel consumed, so 1 h of idling = 7 mi if the truck gets 7 mpg on the road. Older estimates
equated 1 h to 80 mi, which is twice the wear per hour as driving. Reduction in fuel sulfur (which caused
significant damage to the engine) and change in idling revolutions per minute both contributed to the
change.
proportional to fuel consumed, so 1 h of idling = 7 mi if the truck gets 7 mpg on the road. Older estimates
equated 1 h to 80 mi, which is twice the wear per hour as driving. Reduction in fuel sulfur (which caused
significant damage to the engine) and change in idling revolutions per minute both contributed to the
change.