travel range are expected to drop by a factor of about 5. However, even these costs are unlikely to create a mass market for BEVs, because a battery large enough for a 300-mile real-world range would still present significant weight and volume penalties and probably could not be recharged in much less than 30 minutes. Therefore, BEVs may be used mainly for local travel rather than as all-purpose vehicles.

  • BEVs and PHEVs are likely to use lithium-ion batteries for the foreseeable future. Several advanced battery technologies (e.g., lithium-air) are being developed that would address some of the drawbacks of lithium-ion batteries, but their potential for commercialization by 2050 is highly uncertain, and they may have their own disadvantages.
  • PHEVs offer substantial amounts of electric-only driving while avoiding the range and recharge-time limitations of BEVs. However, their larger battery will always entail a significant cost premium over similar HEVs, and their incremental fuel savings will decrease as the efficiency of HEVs improves.
  • The technical hurdles that must be surmounted to develop an all-purpose vehicle acceptable to consumers appear lower for FCEVs than for BEVs. However, the infrastructure and policy barriers appear larger. Well before 2050 the cost of FCEVs could actually be lower than the cost of an equivalent ICEV, and operating costs should also be lower. FCEVs are expected to be equivalent in range and refueling time to ICEVs.
  • If CNGVs can be made competitive (with respect to both vehicle cost and refueling opportunities), they will offer a quick and economical way to reduce petroleum use, but as shown in Figure S.2, the reductions in GHG emissions are insufficient for CNGVs to be a large part of a fleet that meets the 2050 GHG goal.
  • Although fundamental technology breakthroughs are not essential to reach the mpg, performance, and cost estimates in Chapter 2, new technology developments would substantially reduce the development cost and lead time. In particular, continued research to reduce the costs of advanced materials and battery concepts will be critical to the success of electric vehicles.

Fuels (Chapter 3)

  • Meeting the GHG and petroleum reduction goals requires a massive restructuring of the fuel mix used for transportation. The use of petroleum must be greatly reduced, implying retirement of crude oil production and distribution infrastructure. Depending on the progress in drop-in biofuels versus non-liquid fuels, refineries, pipelines, and filling stations might also become obsolete. For BEVs to operate with low GHG emissions, coal- and natural gas-fired electricity generation might have to be greatly reduced unless CCS proves cost-effective. Reliance on natural gas or hydrogen for transportation would require additional infrastructure. With currently envisioned technology, sufficient biofuels could be produced by 2050 to meet the goal of 80 percent reduction in petroleum use if the committee’s vehicle efficiency estimates are attained.
  • With increasing economic natural gas reserves and growing domestic natural gas production mostly from shale gas, there is enough domestic natural gas to greatly increase its use for the transportation sector without significantly affecting the traditional natural gas markets. Currently the cost of natural gas is very low ($2.5 to $3.5/million Btu) and could remain low for several decades. Environmental issues associated with shale gas extraction (fracking) must be resolved, including leakage of natural gas, itself a powerful GHG, and potential contamination of groundwater. There are several opportunities, direct and indirect, to use natural gas in LDVs, including producing electricity for PEVs and producing hydrogen for FCEVs. The fastest way to reduce petroleum use is probably by direct combustion in CNGVs coupled with efficiency improvements, but that approach is likely to interfere with achieving the GHG goal in 2050.
  • Making hydrogen from fossil fuels, especially natural gas, is a low-cost option for meeting future demand from FCEVs, but such methods, by themselves, will not reduce GHG emissions enough to meet the 2050 goal. Making hydrogen with low GHG emissions is more costly (e.g., renewable electricity electrolysis) or requires new production methods (e.g., photoelectrochemical, nuclear cycles, and biological methods) or CCS to manage emissions. Continued R&D is needed on low-GHG hydrogen production methods and CCS to demonstrate that large amounts of low-cost and low-GHG hydrogen can be produced.
  • Natural gas and coal conversion to liquid fuel (GTL, CTL) can be used as a direct replacement for petroleum gasoline, but the GHG emissions from these fuels are slightly greater than those from petroleum-based fuels even when CCS is employed at the production plant. Therefore, these fuels will play a small role in reducing petroleum use if GHG emissions are to be reduced simultaneously.
  • Carbon capture and sequestration is a key technology for meeting the 2050 goal for GHG emissions reductions. Insofar as fossil fuels are used as a source of electricity or hydrogen to power LDVs, CCS will

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