reductions in U.S. oil consumption and greenhouse gas emissions that could be expected in this scenario. HFCVs can yield large and sustained reductions in U.S. oil consumption and greenhouse gas emissions, but several decades will be needed to realize those potential long-term benefits. Figure 5.9 (on facing page) compares the oil consumption that would be required in this scenario with a reference case based on Energy Information Administration high oil-price projections, which include the recent increases in corporate average fuel economy standards. By 2050, HFCVs could reduce oil consumption by two-thirds. Greenhouse gas emissions would follow a similar trajectory if hydrogen produced from coal in large central stations were accompanied by carbon separation and sequestration.

The study then compared those reductions with the potential impact of alternative vehicle technologies (including conventional hybrid-electric vehicles) and biofuels oil consumption and greenhouse gas emissions. Over the next two decades, those approaches could deliver much greater reductions in U.S. oil use and greenhouse gas emissions than could HFCVs, but hydrogen offers greater longer-term potential. Thus, the greatest benefits will come from a portfolio of research and development in technologies that would allow the United States to nearly eliminate oil use in LDVs by 2050 (see Figure 5.10 on facing page). Achieving that goal would require substantial new energy-security and environmental-policy actions in addition to technological developments. Broad policies aimed at reducing oil use and greenhouse gas emissions will be useful, but they are unlikely to be adequate to facilitate the rapid introduction of HFCVs.

REFERENCES

Agrawal, R., N.R. Singh, F.H. Ribeiro, and W.N. Delgass. 2007. Sustainable fuel for the transportation sector. Proceedings of the National Academy of Sciences USA 104: 4828-4833.

Arcoumanis, C., C. Bae, R. Crookes, and E. Kinoshita. 2008. The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review. Fuel 87:1014-1030.

Chase, R. 2006. DuPont, BP join to make butanol: They say it outperforms ethanol as a fuel additive. USA Today, June 26.

DOE (U.S. Department of Energy). 2007. DOE selects six cellulosic ethanol plants for up to $385 million in federal funding. Available at http://www.energy.gov/print/4827.htm. Accessed October 16, 2008.



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