A comparison of greenhouse gas emissions and local area pollution of highspeed rail and air travel between Los Angeles and Las Vegas
Global warming is one of the most discussed global environmental issues in the world today. Global warming is driven by fossil fuel combustion emissions known as Green-house Gases (GHG). One of the major contributors to GHG emissions is the transport sector, emitting approximately 30% of total U.S. CO 2 emissions in 2010. Air travel contributed approximately 3.5% of total U.S. CO2 in 2008. High-speed Rail (HSR) is often touted as cleaner, more sustainable mode of transport than air travel. HSR is one of few modes of transport capable of competing with air travel for short to medium-haul distances. There has been considerable study of GHG emissions of each independently. Research has also been carried out into the economics and competition of these transport modes. However, there has been very limited study of the comparative emissions of each, apart from one study in Europe (Givoni, 2007). The current study was undertaken with the goal of quantifying potential emission savings due to mode substitution from air travel to HSR in the Los Angeles to Las Vegas corridor. This study only considered the emissions which occurred from the combustion of the relevant fuels, either in power plants or the engines of an aircraft. Emissions from fuel production/refining or transport of fuels were not considered. Another issue compared was Local Area Pollution (LAP), which is a measure of the severity of emissions effect on the environment. This was examined because all emissions from HSR occur close to the surface of the earth, and hence effect the local environment, while only a portion of aircraft emissions do.^ This study was carried out using internationally recognized emission inventory methodologies. For the air travel emission estimate methodologies and data published by the Intergovernmental Panel on Climate Change (IPCC) and the International Civil Aviation Organization (ICAO) were used. The HSR energy use was estimated from energy use data from currently running HSR programs, in France, UK and Spain (Alvarez, 2007; Kemp, 2007). The emissions were then estimated using an adjusted tier 3 method. For aviation emissions a tier three method was also used. ^ The findings of this research are mixed. HSR would emit 66% less GHG emissions using today's energy mixes for California and Nevada. Using California's 2020 target energy mix HSR would emit 80% less GHG emissions. However, using today's energy mix HSR would cause 33% more LAP than air travel. Using California's 2020 mix the HSR would cause 22% less LAP the air travel. However this 20% improvement would likely be eroded by aircraft emissions improvement between now and 2020. ^ To conclude, this research found that HSR does offer significant GHG emission reductions, when compared to air travel between Los Angeles and Las Vegas. However is less clear regarding LAP, though HSR has the potential to create savings here in the future as well. For other corridors around the U.S.A., earmarked for HSR, similar studies should be carried out to examine the benefits of such mode transfer.^
Michael J. Dyrenfurth, Purdue University.
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