Environmental Engineering Reference
In-Depth Information
Fig. 4.2 U.S. petroleum product demand and supply (millions of barrels per day)
Source: DOE 2006 annual energy outlook [1]
Considering the uncertainties of long-range predictions and judging solely by lowest
life-cycle energy use and greenhouse (GHG) releases, there is no current basis for
preferring either fuel cell (FC) or ICE hybrid power plants for mid-size automobiles
over the next 20 years or so using fuels derived from petroleum or natural gas. That
conclusion applies even with optimistic assumptions about the pace of future FC
development. Hybrid vehicles are superior to their nonhybrid counterparts and their
advantages are greater for ICE than for FC designs.
In other words, advanced hybrid powertrains incorporating ICEs are
expected to be competitive with FC vehicles in 2020, and beyond, even with
optimal advancements assumed for FC and hydrogen processing technologies.
In all cases, these predictions assume aggressive technological advances in
electric drivetrain components, the ICE and the coordinated design, control
and manufacture of the drivetrain. Substantial improvements in ICEs are also
required and are possible [3]:
...historical trends showing the ratio of gasoline engine power to displaced volume
determined by Chon and Heywood [4] show a nearly linear improvement of about
0.5% per year. Future technological improvements such as increasing use of variable
valve timing, gasoline direct-injection, improved turbocharger performance for diesels,
and reduced engine friction, are expected to continue this trend. Hence for 2020, the
wide-open-throttle (WOT) torque for these engines is increased by 10% overall.
In other words, novel combustion strategies, including low temperature
combustion (LTC), yield promise for cleaner and more efficient powertrains.
4.1.2 Opportunities for Leveraging Novel ICE Technologies
Residual-affected LTC and other novel combustion strategies represent signif-
icant advances for ICEs. As noted in Section 4.1.1, hybrid powertrains
