June 9, 2009

WE'RE GONNA NEED A BIGGER DIG...:

Train can be worse for climate than plane (Catherine Brahic, 6/08/09, New Scientist)

True or false: taking the commuter train across Boston results in lower greenhouse gas emissions than travelling the same distance in a jumbo jet. Perhaps surprisingly, the answer is false.

A new study compares the "full life-cycle" emissions generated by 11 different modes of transportation in the US. Unlike previous studies on transport emissions, Mikhail Chester and Arpad Horvath of the University of California, Berkeley, looked beyond what is emitted by different types of car, train, bus or plane while their engines are running and includes emissions from building and maintaining the vehicles and their infrastructure, as well as generating the fuel to run them. (Table 1 on page 3 has a complete list of components that were considered).

Transport studies expert Abigail Bristow of Loughborough University, UK, who was not involved in the study, says it is valuable because it attempts to compare transport on equal terms. To do this, Chester and Horvath calculated how many passengers each train, plane, bus or car would carry in its lifetime and how many kilometres it would cover. The pair took into account how much each infrastructure component – such as tracks, roads and airports – is used in its lifetime.

Including these additional sources of pollution more than doubles the greenhouse gas emissions of train travel. The emissions generated by car travel increase by nearly one third when manufacturing and infrastructure are taken into account. In comparison to cars on roads and trains on tracks, air travel requires little infrastructure. As a result, full life-cycle emissions are between 10 and 20 per cent higher than "tailpipe" emissions.

Cars emitted more than any other form of transport with the notable exception of off-peak buses, which often carry few passengers. The researchers found that travelling 1 kilometre on a nearly empty bus during off-peak hours emits eight times more per person than taking the same bus at rush hour – suggesting peak-time commuters may suffer, but they do less harm to the environment.


Can't you just see the lines of jumbo jets driving commuters across the city?

Posted by Orrin Judd at June 9, 2009 7:04 PM
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