FIGURE C.1 Number of vehicles in the Hydrogen Report Reference Case. SOURCE: NRC, 2008.

FIGURE C.2 Fuel economy for vehicles in the Hydrogen Report Reference Case. SOURCE: NRC, 2008.

FIGURE C.3 Number of vehicles in the ICEV Efficiency Case (Hydrogen Report Case 2). SOURCE: NRC, 2008.

much electricity and fuel are consumed over a drive cycle, both of which are influenced by three factors:

• The size of the battery. The larger the PHEV battery, the greater the fraction of the car’s energy use that can be provided by electricity. Battery size is sometimes expressed as all-electric range (AER), the distance that could be traveled on just the battery if the car is operated in CD mode without using the engine.

FIGURE C.4 Fuel economy for the ICEV Efficiency Case (Hydrogen Report Case 2). SOURCE: NRC, 2008.

FIGURE C.5 Biofuel supply for the Biofuels-Intensive Case (Hydrogen Report Case 3). SOURCE: NRC, 2008.

FIGURE C.6 Numbers of light-duty vehicles for portfolio approach, where PHEVs are combined with efficient ICEVs and HEVs.

• Pattern of driving. The fraction of miles traveled on electricity can also vary, depending on the driver’s pattern of trips. If the driver takes only short trips (less than the all-electric range of the battery), all the miles could all be traveled on electricity. For longer trips, the driver will deplete the battery and will have to use the engine.

• Control strategy of the PHEV when driven in CD mode. Some PHEVs (the PHEV-40 in this report) use an all-electric strategy, where the battery is depleted to a minimum SOC.