Freight Energy Use Disaggregated by Commodity: Comparisons and Discussion

The analysis of energy consumption in freight transportation is almost always approached by disaggregating overall energy consumption by mode, which then provides a basis for understanding trends and underlying factors that influence them and for developing conservation policies. Another important approach is to disaggregate by commodity, because it is commodity flows that generate the modal vehicle flows and hence the modal energy consumption in transportation. Thus changes in energy use by commodity are important factors in understanding trends in energy consumption and may provide a basis for energy conservation policies centered on industries using transportation. Total freight energy consumption is estimated for a range of commodity groups using an activitybased approach to energy consumption, where total freight activity is decomposed into components by mode and by commodity group, and then each component is multiplied by an intensity estimate to calculate total energy use for that commodity group. Two important findings are discussed: (a) commodity groups with high energy growth between 1972 and 1993 had a combination of substantial ton-mile growth and modal shift to truck, and (b) commodity groups of finished products with a high average value per ton in general have a much higher average freight energy intensity than raw materials with a low average value per ton.