Co-optimization of Heavy-Duty Fuels and Engines: Cost Benefit Analysis and Implications

Heavy-duty vehicles
require expensive aftertreatment systems for
control of emissions such as particulate matter (PM) and nitrogen
oxides (NOx) to comply with stringent
emission standards. Reduced engine-out emissions could potentially
alleviate the emission control burden, and thus bring about reductions
in the cost associated with aftertreatment systems, which translates
into savings in vehicle ownership. This study evaluates potential
reductions in manufacturing and operating costs of redesigned emission
aftertreatment systems of line-haul heavy-duty diesel vehicles (HDDVs)
with reduced engine-out emissions brought about by co-optimized fuel
and engine technologies. Three emissions reduction cases representing
conservative, medium, and optimistic engine-out emission reduction
benefits are analyzed, compared to a reference case: the total costs
of aftertreatment systems (TCA) of the three cases are reduced to
$11,400­(1.63 ¢/km), $9,100 (1.30 ¢/km), and $8,800 (1.26
¢/km), respectively, compared to $12,000 (1.71 ¢/km) for
the reference case. The largest potential reductions result from reduced
diesel exhaust fluid (DEF) usage due to lower NOx emissions. Downsizing aftertreatment devices is not likely,
because the sizes of devices are dependent on not only engine-out
emissions, but also other factors such as engine displacement. Sensitivity
analysis indicates that the price and usage of DEF have the largest
impacts on TCA reduction.