The 2050 petroleum reduction goal is easier to meet than the 2050 GHG goal because more options can be employed. In fact, reducing GHGs by 80 percent is likely to require reducing petroleum use by at least 80 percent. Petroleum use by the light duty fleet was 125 billion gallons gasoline in 2005 (EIA, 2011), so the targets are 62.5 billion gallons in 2030 and 25 billion in 2050.

GHG emissions from the LDV fleet in 2005 were 1,514 million metric tons of CO2 equivalent (MMTCO2e) on a well-to-wheels basis (EPA, 2012). An 80 percent reduction from that level means that whatever fleet is on the road in 2050 can be responsible for only 303 MMTCO2e/year. That is the budget within which the fleet must operate to meet the goal.

Achieving an 80 percent reduction in LDV-related emissions is only possible with a very high degree of net GHG reduction in whatever energy supply sectors are used to provide fuel for the vehicles. In short, it is not possible to greatly “de-carbonize” LDVs without greatly de-carbonizing the major energy supply sectors of the economy.

The committee determined potential costs and performance levels for the vehicle and fuel options. Because of the great uncertainty in estimating vehicle cost and performance in 2050, the committee considered two levels, midrange and optimistic. Midrange goals for cost and performance are ambitious but plausible in the committee’s opinion. Meeting this level will require successful research and development and no insurmountable barriers, such as reliance on critical materials that may not be available in sufficient quantities. The more optimistic goals are stretch goals: possible without fundamental technology breakthroughs, but requiring greater R&D and vehicle design success. All the vehicle and fuel cost and performance levels are based on what is achievable for the technology.

Other factors also will be very important in determining what is actually achieved. In particular, government policy will be necessary to help some new and initially costly technologies into the market, consumer attitudes will be critical in determining what technologies are successful, and of course, the price and availability of gasoline will be important in determining the competitiveness of alternative vehicles and fuels.

1.1 APPROACH AND CONTENT

To analyze all these issues, the committee constructed and analyzed various scenarios, combining options under the midrange and optimistic cost and performance levels to see

BOX 1.1
Analytical Techniques Used in This Report

The committee relied on four models to help form its estimates of future vehicle characteristics, their penetration into the market, and the impact on petroleum consumption and GHG emissions. Chapter 2 and Appendix F describe two of the models. One is an ICEV model developed by a consultant that projects vehicle efficiency out to 2050 by focusing on reduction of energy losses, rather than the usual technique of adding efficiency technologies until the desired level is reached. The committee’s approach avoids the highly uncertain predictions of which technologies will be employed several decades from now and ensures that efficiency projections are physically achievable and that synergies between technologies are appropriately accounted for. The second is a spreadsheet model of technology costs developed by the committee, which focused on applying consistent assumptions across all of the different powertrain types. The analytical approach for both models is fully documented and the data are available in Appendix F. The methodology and results for both of these models were intensively reviewed by the committee, the committee staff, another consultant, and experts from FEV, Inc., an engineering services company. Reviewers of this report were also selected for their ability to understand this approach, which they endorsed.

The VISION and LAVE-Trans models are described in Chapter 5 and Appendix H. VISION is a standard model for analyzing transportation scenarios for fuel use and emissions. It is freely available through the U.S. Department of Energy. The committee modified it for consistency with the committee’s assumptions such as on vehicle efficiencies and usage and fuel availability. The committee carefully monitored the modifications and reviewed the results, which are consistent with other analyses.

LAVE-Trans is a new model developed by a committee member for an analysis of California’s energy future and expanded to the entire nation by the committee. It is unique among models in that it explicitly addresses market responses to factors such as vehicle cost and range, aversion to new technology, and fuel availability. It analyzes the effectiveness of policies in light of these market responses. The committee and staff spent considerable time reviewing LAVE-Trans and its results. In addition to presentations and discussions at committee meetings, one committee member and the study director spent a day going over the model with the developer and his associates. Another committee member examined intermediate calculations as well as model outputs. The results were also compared to VISION results for identical inputs and assumptions. These examinations led to recalibrations and changes in model assumptions. Reviewers of this report were also selected for their ability to understand the model, and they confirmed its validity.



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