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Environmental sciences, Transport engineering, Energy and fuels
This paper applies a life cycle methodology to estimate activity-related contributions of transport modes to GHG emissions. The methodology uses national input-output tables, environmental accounts, household budget data and nutritional data to derive food-sector GHG coefficients of consumption for ten European countries. The food energy requirements for each mode of transport are estimated taking account of the modal activity level and energy requirements. Walking, cycling, driving and bus travel are considered. Typical national food energy-related emissions for walking, cycling, and driving ranged from 25.6 - 77.3 gCO2-eq/pass.km, 10.4 - 31.4 gCO2-eq/pass.km and 1.7 - 5.2 gCO2-eq/pass.km; passenger transport was found to result in no food-related emissions above those for a resting individual. Emissions vary between countries and depend on the emissions intensities of their energy sectors as well as food prices and average body weights. A life cycle assessment of modal emissions in the UK was undertaken using the food-energy emissions intensities estimated. UK car travel was found to have the highest emissions intensity, followed by bus travel, cycling and walking.
Duffy, A. & Crawford, R. (2013) The effects of physical activity on greenhouse gas emissions for common transport modes in European countries. Transportation Research Part D: Transport and Environment, vol. 19, March 2013, pp. 13-19. doi:10.1016/j.trd.2012.09.005.