FIGURE C.8 National VMT fraction available for substitution by a PHEV using 100 percent electric charge-depleting mode. SOURCE: Elgowainy et al., 2009.

FIGURE C.8 National VMT fraction available for substitution by a PHEV using 100 percent electric charge-depleting mode. SOURCE: Elgowainy et al., 2009.

FIGURE C.9 Tank-to-wheels energy use in advanced vehicles, assuming 44 percent blending during charge-depleting operation. SOURCE: Kromer and Heywood, 2007.

FIGURE C.9 Tank-to-wheels energy use in advanced vehicles, assuming 44 percent blending during charge-depleting operation. SOURCE: Kromer and Heywood, 2007.

FIGURE C.10 Energy consumption in a PHEV-30 as electricity and gasoline for different blending strategies in CD mode. SOURCE: Kromer and Heywood, 2007.

FIGURE C.10 Energy consumption in a PHEV-30 as electricity and gasoline for different blending strategies in CD mode. SOURCE: Kromer and Heywood, 2007.

Step 4.
Estimate PHEV Gasoline and Electricity Use over Time

The committee reasoned that PHEV engine and vehicle technologies (e.g., aerodynamics and rolling resistance) would improve at the same rate as fuel economy technologies in the ICEV Efficiency Case: 2.7 percent per year from 2010 to 2025; 1.5 percent per year from 2026 to 2035; and 0.5 percent per year from 2036 to 2050. Combining these improvement rates and the derived energy-use ratios in Table C.1, the committee then developed assumed values for gasoline and electricity use vs. time for the PHEV-10 and PHEV-40 from 2010 to 2050.

Figure C.11 shows the resulting gasoline use for PHEV-10 and PHEV-40 vehicles for the Optimistic technology case. Gasoline ICEV and HEV gasoline use in the Reference Case and high-efficiency cases are shown for comparison. Figure C.12 shows the estimated electricity use for both the PHEV-10 and the PHEV-40.

TABLE C.1 Ratio of Energy Use in PHEVs Compared to Energy Use in Gasoline HEVs

Ratio

Energy Use in PHEVs vs. Gasoline Use in HEVs

PHEV-10 (Blended CD)

PHEV-40 (All-Electric CD)

Gasoline use in PHEVs: gasoline use in HEVs

0.81

0.45

Electric energy use in PHEVs: gasoline energy use in HEVs

0.09

0.24

NOTE: The PHEV-10 is assumed to operate in blended mode and the PHEV-40 in all-electric mode during CD operation. As a check, the committee also calculated ratios for PHEV electrical energy use and gasoline use as compared to a hybrid vehicle for two other PHEV modeling studies (Elgowainy et al., 2009; Simpson, 2006). The results were broadly similar for the PHEV-10 (gasoline use was 85-88 percent of HEV gasoline use and electricity energy use was 4-5 percent of HEV gasoline energy use). For the PHEV-40, these two studies estimated gasoline consumption ratios of 55-60 percent, and electricity use 12-15 percent (higher gasoline use and lower electricity use than Kromer and Heywood). Part of the difference may be because Elgowainy et al. (2009) and Simpson (2006) simulated only blended-mode CD operation, while Kromer and Heywood (2007) considered all-electric mode.

SOURCE: Adapted from Kromer and Heywood (2007).



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