produce components for both voltage levels, and suppliers would have to stock twice as
many parts for many years. It is not obvious to many stakeholders that the economic
benefits of a 42-v system would offset the costs of implementing it.
Therefore, it was recommended that DOE fund a two-phase project to clarify the
issue. The first phase would be a paper study where all of the known or estimated benefits
and costs are tabulated and compared. If the results of the paper study are positive, then a
concept vehicle should be constructed with a 42-v electrical system and the variable-
speed components that it would enable. The concept vehicle could then be used to
convince key stakeholders of the benefits.
The second most significant issue identified by the group was that of turning off
the engine when the truck is at a rest stop. It is a "no-brainer" that substantial fuel savings
would be achieved in this way. However, some power usually is required even when the
truck is at rest to maintain the cab climate and "hotel" loads and to restart the engine.
This requires either "shore power" at rest stops, which is not generally available at this
time and would be expensive to install, or an auxiliary power unit (APU) on every truck.
The latter option would add weight and cost and appears to be less efficient than the
shore-power alternative. It was felt that the time to achieve one or the other alternative
could be shortened significantly if DOE would fund a paper study to quantify the benefits
versus costs, publicize the results of the study, and support a demonstration program to
A number of other topics were recognized as having energy-saving potential, but
they were considered of lower priority, and time did not permit a detailed discussion of
each. Following are some of the comments that were made:
Shutters: In the past, shutters in front of the radiator had been widely
used, but less than 1% of new trucks have them. While they are no
longer needed for temperature control, the group speculated that they
might be useful for aerodynamic reasons. However, they need
clarification of comments made by Rose McCallen regarding the
energy loss associated with air flow through the engine compartment.
It was suggested that DOE clarify, confirm, and, if necessary, validate
Nanofluids: More efficient heat-transfer fluids hold the potential for
weight reduction because less fluid would be required. This also offers
the potential for cost reduction unless the cost of the new fluid is
proportionately higher than the weight savings.