Emissions Regulations, An Integral Part of A Larger Policy Toolkit

The car driven sprawl of the Americas’ largest metropolis, Mexico City. Photo by Pablo Pozo.

Aiga Stokenberga, the author of this blog post, completed this research as an intern in EMBARQ in Summer 2011.  Her research product is one of the last articles co-authored by the late Dr. Lee Schipper. EMBARQ encourages young researchers working in energy and transport to apply to the Lee Schipper Memorial Scholarship

Last week, a study co-authored by this blogger with the late Lee Schipper – the founder of EMBARQ- analyzing energy usage by mode per activity, modal energy intensity, using ASIF (a methodology which unpacks transport energy use by activity, modal share, energy and carbon intensities) was published in the Transportation Research Board’s (TRB) Transportation Research Record.  The 2,287th issue of the prestigious technical journal reflects the work that was presented at the 91st annual Transportation Research Board conference this January in Washington, D.C.

The research focuses on the transport sector’s is increasing contribution to Mexico’s carbon footprint as well as its associated externalities, including congestion and increasing energy supply costs. Schipper and I examined the above  in terms of transport activity, energy use, and emissions with publicly available data, to identify trends in Mexico City level. We developed, using the most recent (2007) Origin, Destination survey data for Mexico City,  scenarios of future CO2 emissions based on several alternative assumptions about the modal share of mass transport versus private transport. In applying these scenarios, we conclude that measures promoting a shift toward non-motorized transport and mass transit will both be essential complements to increased fuel economy standards if Mexico City’s recent shift toward high capacity modes -with lower energy intensity- is to be maintained.

This bottom-up approach relying on national data, first applied in the early 1990s ,  has been used in numerous previous studies on transport energy use and emissions in developed countries, including a relatively recent analysis by Kamakate & Schipper that looked at trends in truck freight energy use and carbon emissions in OECD countries. In a related study “peak travel” energy use in a number of industrialized nations is examined using similar methods. In one of the most recent papers on the topic, published in 2011 in Transport Policy, Schipper examined trends in automobile use, fuel economy and CO2 emissions in the European Union, United States, and Japan.

Similar to the analysis of Mexico’s urban transport energy use and emissions, the study concluded that vehicle on-road fuel intensity in the analyzed countries had improved and that reductions in transport carbon emissions might result from recent strengthening of emissions targets for new vehicles. On the other hand, when also accounting for trends in vehicle size and power, one of the key take-aways from the 2011 study – similarly to the present one specific to Mexico – was that fuel economy technology, while important, is not the only factor driving changes in on-road fuel economy, vehicle efficiency and transport emissions across countries.


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