The stationary power sector could serve the transportation market in another way by providing electric power to charge batteries. These could then power electric vehicles (EVs) or plug-in hybrid vehicles (PHEVs). In this case, electric power, generally off peak at attractive prices, would be used to recharge batteries, normally at the vehicle’s long-term “parked” location (home of a residential customer, garage for a fleet vehicle, etc.). PHEVs might have a range of about 20-40 miles. When the battery charge is depleted, a regular gasoline engine would start to operate the vehicle. PHEVs are described in Chapter 4.
Either type of electric vehicle would be much easier to implement than HFCVs, especially the PHEV. Little new infrastructure would be needed for the introduction of PHEVs, although new generating capacity and possibly transmission lines would be needed eventually. Infrastructure and logistics are much bigger problems for the introduction of HFCVs. EVs might require the construction of public charging stations to permit long-distance operation. The viability of both EVs and PHEVs depends on significant improvements in battery capability.
Two types of PHEVs are under consideration: the AER (all-electric range) and the “blended” PHEV. The AER has a large electric motor that provides all the traction power and a large battery to allow considerable all-electric vehicle operation. It also has a small engine that acts as a range extender when the battery is depleted. The blended PHEV has a larger engine and a smaller electric motor which operate in parallel to drive the wheels. The blended configuration is similar to current hybrids but with a larger battery to allow some operation on just electric power though less than the AER.
The use of off-peak power is particularly attractive. If off-peak power is available for $0.07/kWh, it is equivalent to gasoline at $0.77 per gallon after taking into account the differences in efficiency (Pratt et al., 2007).2 As this example demonstrates, time-of-day pricing would have to be available to make off-peak power economical. This is an excellent example of how an electric utility, with the approval of its state PUC, could help make electric vehicles financially attractive. Similar incentives could be put in place for any plug-in or hydrogen-based concept.
The near-term focus should be on the blended version since the AER approach essentially has the same problems as full electric vehicles—namely, the need for a large, advanced battery and the need for rapid growth of charging stations. In a blended PHEV, the advanced batteries will be closer in size to those found in today’s hybrid vehicles. With currently envisioned technologies, it would take an AER PHEV up to 6.5 hours to recharge (at 110 V) for a 40-mile battery range, whereas a blended PHEV would require only 2 hours (at 110 V) for a 5-mile battery range (Kawai, 2007).3 It should be emphasized that the critical path developmental item for PHEVs is the advanced battery (e.g., lithium ion) that either the AER or the blended version will require.
The stationary power sector itself could supply the needs of about 40 percent of the current light-duty fleet for an average 30+ miles/day using off-peak power from current power