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

The world is searching for a meaningful answer to the likelihood that the continued build-up of greenhouse gases in the atmosphere will cause significant changes in the earth's climate. If there is to be a solution, technology must play a central role. This paper presents the results of an assessment of the potential for cost-effective technological changes to reduce greenhouse gas emissions from the U.S. transportation sector by the year 2010. Other papers in this session address the same-topic for buildings and industry. U.S. transportation energy use stood at 24.4 quadrillion Btu (Quads) in 1996, up 2 percent over 1995 (U.S. 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 U.S. greenhouse gas emissions (U.S. DOE/EIA, 1986a, p. 12). Transport's energy use and CO2 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 CO2 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 CO2 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: emissions reduced to 1990 levels by 2015.