higher-carbon EIA grid, the GHG reduction with PHEV-10s (PHEV-40s) is about 55 percent (59 percent), about the same as for efficiency + biofuels.
GHG and oil reductions for PHEVs are small before 2025 because of the time needed for vehicles to penetrate the market.
PHEV GHG benefits depend on the grid mix:
PHEV benefits are small compared with HEVs for the EIA grid.
With a low-carbon grid (EPRI/NRDC mix), introduction of PHEV-40s could significantly lower GHG emissions relative to HEVs.
Increasing conventional vehicle efficiency alone (without PHEVs) can reduce oil use by about 40 percent in 2050 compared with the Reference Case. Adding PHEV-10s at the Maximum Practical rate can reduce oil use an additional 7 percent, while PHEV-40s can reduce it an additional 23 percent.
Implementing efficiency plus biofuels reduces gasoline use by about 65 percent compared with the Reference Case. Adding PHEV-10s at the Maximum Practical rate can reduce oil use an additional 7 percent, while PHEV-40s can reduce it 23 percent.
A portfolio approach incorporating efficiency, more use of HEVs and biofuels, as well as PHEVs, yields greater reductions in oil use and GHG.
Long-term GHG and oil-use reductions are greater with HFCVs than PHEVs for similar levels of energy supply decarbonization (NRC Hydrogen scenario; EPRI/NRDC grid). If PHEVs are charged from the EIA grid, GHG emission reductions with PHEVs will be much less than with HFCVs.
Transition costs and timing to breakeven are similar for HFCVs and PHEV-10s, i.e., tens of billions of dollars total, spent over a 10-20 year period. This is less than the current corn ethanol subsidy of about $10 billion per year.
Majority of transition cost (more than 80 percent) is for vehicle buydown. Average price subsidy needed for HFCVs and PHEV-10s over a 10-15 year transition period is similar, about $5000 to $6000 per car for PHEV-10s, and $7,000 to $9,000 per car for HFCVs.
Transition costs for PHEV-40s are significantly higher than for PHEV-10s, because of higher vehicle first cost. Break-even year for the PHEV-40 is 2040 in the Optimistic Technology Case, but not until 2047 for the Probable Case, unless the oil price is high or the cost of batteries can be reduced rapidly.
Slower Probable Case transition strategies sometimes have a lower overall transition cost than the Maximum Practical Case. This is true because the Maximum Practical Case buys large numbers of expensive early PHEVs.
Transition costs are sensitive to oil prices and to vehicle cost increment, which depends on battery cost assumptions, but are not very sensitive to electricity price.
Infrastructure costs for PHEVs might average $1000 per car for residential charging.
Total infrastructure capital costs to breakeven are the same order of magnitude for PHEV-10s and HFCVs, although early infrastructure logistics are less complex with PHEVs.
Bringing PHEVs to cost-competitiveness will take several decades and require many billions of dollars in support. Transition costs for PHEV-40s are significantly larger than for PHEV-10s, but the reduction in gasoline consumption is greater also.
GHG benefits of PHEVs depend on the grid mix. With a business-as-usual EIA grid mix, the benefits of PHEVs are similar to those for efficient gasoline HEVs. With a substantially decarbonized grid, PHEVs can save 4-16 percent more GHG emissions than efficient HEVs.
The PHEV transition cost and timing results are sensitive to the oil price and the battery cost. But even with relatively high oil prices (AEO high oil price case $80-$120 per barrel) and achievement of aggressive battery goals (similar to the DOE goals), it will take 15-20 years and tens to hundreds of billions of dollars to bring PHEV-40s to commercial success.