Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportations Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
conventional diesel HDVs are provided truck class group in Table 3.3L (Frey and Kuo,
2007; Schubert and Kromer, 2008; Vyas et al., 2002; CARB, 2008a; NESCCAF/ICCT, 2009).
Unit costs for trailer treatments are multiplied by 2.5 to account for the ratio of trailers to
tractors.
Table 3.3G
Incremental Costs of HDV Resistance and Powertrain
Technologies (Dollars per Vehicle)
Class 4-7 Class 8
Technology Minimum Maximum Minimum Maximum
Basic cab aero 750 750 750 750
Enhanced cab aero 800 800 1,500 1,500
Trailer edge curvatures - - 1,250 1,250
Advanced integrated aerodynamics - - 24,500 24,500
Low-rolling resistance tires & aluminum
wheels 1,680 1,680 3,920 3,920
Auxiliary electrification 1,000 1,000 1,000 1,000
Lubricants and bearings 500 500 500 500
Peak cylinder pressure - - 1,000 1,000
Improved injection/combustion 2,000 2,000 1,500 1,500
Turbocompounding (mechanical) - - 2,650 2,650
Bottoming cycle - - 15,100 15,100
Hybridization 20,500 26,000 20,500 26,000
Weight reduction 1,000 2,000 1,000 2,000
Boat tails - - 1,250 5,600
Load profile improvement - - 0 a 0 a
Front fairings 2,000 2,500 2,000 2,500
a
Does not include operator labor.
Cobenefits
As noted, many of the engine system improvements described above raise combustion
temperatures and therefore engine-out NO x emissions. The increase in NO x formation is
generally more of a limiting factor to increases in engine efficiency than PM emissions.
Selective catalytic reduction (SCR) technologies being adopted to meet the upcoming 2010
NO x standards can be designed to lessen the energy requirements associated with exhaust
gas recirculation (EGR) systems by permitting greater engine-out NO x levels, in turn
reducing fuel consumption (Greszler, 2008).
Certain powertrain improvements also can improve engine driveability by increasing
available torque at a wide range of engine speeds. Improved fuel injection also can result
in reduced formation of NO x and PM, although reductions in tailpipe PM may be
negligible due to the great effectiveness of DPFs in 2007 and later diesels.
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