The potential for energy-efficient technologies to reduce carbon emissions in the United States: transport sector

This paper presents the results of an assessment of the potential for cost-effective technological changes to reduce greenhouse gas emissions from the US transportation sector by the year 2010. US transportation energy use stood at 24.4 quadrillion Btu (Quads) in 1996, up 2 percent over 1995 (US DOE/EIA, 1997, table 2.5). Transportation sector carbon dioxide emissions amounted to 457.2 million metric tons of carbon (MmtC) in 1995, almost one third of total US greenhouse gas emissions (US DOE/EIA, 1996a, p.12). Transport's energy use and CO/sub 2/ emissions are growing, apparently at accelerating rates as energy efficiency improvements appear to be slowing to a halt. Cost-effective and nearly cost-effective technologies have enormous potential to slow and even reverse the growth of transport's CO/sub 2/ emissions, but technological changes will take time and are not likely to occur without significant, new public policy initiatives. Absent new initiatives, we project that CO/sub 2/ emissions from transport are likely to grow to 616 MmtC by 2010, and 646 MmtC by 2015. An aggressive effort to develop and implement cost-effective technologies that are more efficient and fuels that are lower in carbon could reduce emissions by about 12% in 2010 and 18% in 2015, versus the business-as-usual projection. With substantial luck, leading to breakthroughs in key areas, reductions over the BAU case of 17% in 2010 and 25% in 2015, might be possible. In none of these case are CO/sub 2/ emissions reduced to 1990 levels by 2015.