1.         INDICATOR

(a)                Name:  Intensity of Energy Use in Transportation.  

(b)               Brief Definition:  Energy consumption for transportation relative to the amount of freight or passengers carried and the distance traveled.  

(c)                Unit of Measurement:  Magajoules per tonne-kilometer (mJ/tonne-km) for freight, and Megajoules per passenger-kilometer (mJ/passenger-km) for passengers.  

(d)               Placement in the CSD Indicator Set:  Economic/Consumption and Production Patterns/ Energy Use.  

2.         POLICY RELEVANCE

(a)                Purpose:  Transportation is a major consumer of energy, mostly in the form of fossil fuels, and the share of transportation in energy consumption is generally increasing. The indicator is a measure of how efficiently energy is used for moving goods and people. The indicator can be used to monitor trends in energy consumption for transportation and for international comparisons. Separation of freight and passenger travel is essential.  

(b)               Relevance to Sustainable/Unsustainable Development (theme-sub-theme):  Transportation serves economic and social development through distribution of goods and services and through personal mobility.  However, energy consumption for transportation also leads to air pollution and climate change.  Reducing energy intensity (increasing energy efficiency) in transportation can reduce the environmental impacts of transportation while maintaining the economic and social benefits. 

(c)        International Conventions and Agreements:  UNFCCC and its Kyoto Protocol.  The European Union voluntary agreement on greenhouse gas (GHG) emissions from automobiles (to which Japanese and Korean producers have also agreed) require reductions in GHG emissions per kilometer from new automobiles.  

(d)               International Targets/Recommended Standards:  Many industrialized countries have targets for reducing energy use and carbon emissions from transportation, for which these energy intensities are key indicators. 

(e)                Linkages to Other Indicators:  This indicator is one of a set for energy intensity in different sectors (manufacturing, transportation, commercial/services and residential), with the indicator for energy use per unit of GDP as an aggregate energy intensity indicator.  These indicators are also linked to indicators for total energy consumption, greenhouse gas emissions, and air pollution emissions.  This indicator is also linked to the indicator for distance traveled per capita by means of transport.      

3.         METHODOLOGICAL DESCRIPTION

(a)                Underlying Definitions and Concepts:  Energy consumption per unit of transportation activity is a key measure of how efficiently transportation systems convert energy into human mobility and goods distribution. Because it is not meaningful to add freight and passenger travel, these types of transportation must be disaggregated. Separating the two activity measures is generally not difficult, but separating the energy consumption is often complicated.

(b)               Measurement Methods:

§         Energy Use:  Energy consumption should be measured for each kind of vehicle, including two-wheelers, automobiles, busses, small trucks, heavy trucks, and miscellaneous road vehicles, as well as trains, ships and aircraft for domestic transport, and even pipelines.  In general, however, national energy balances are only disaggregated by fuel and broad traffic type: road, rail, water, and air.  Considerable work is required to disaggregate road fuels consumed by vehicle type.  It is important to take into account the different energy content and carbon emissions in different fuels and not simply add the weights or volumes of different fuels consumed (e.g., tonnes, or cubic metres in the case of natural gas).  Some of the difficulties in disaggregating road fuels consumed by vehicle type are explained in Schipper et al. (1993). International air or marine transportation should not be included. Electric power consumption for rail, subway and trams, as well as electric road vehicles, should be converted to primary energy consumption, although there is no standard method for such conversion.

Unit:  Preferable energy units are multiples of joules, usually terajoules (1012J), petajoules (1015J), or exajoules(1018J), converted from weights or volumes of fuels at net heating values.  

·        Output or Activity:  There are two different measures of activity. Vehicular activity, in vehicle-km, provides a measure of traffic that is important for transport policy and road and infrastructure planning.  Most often, these data can be divided further into basic vehicle types. However, economic and human activity is better measured in passenger-km and tonne-km, taking into account utilisation or load factors.  A bus carrying 20 passengers for 10 km (200 passenger-km) is less energy intensive (more energy efficient) than the same bus carrying 5 passengers for the same distance (50 passenger-km). Similarly, a fully-loaded truck is less energy intensive than the same truck carrying a partial load.  

·        Indicators:   

(i)      Vehicle Intensities:  Energy consumption per vehicle-km by vehicle and fuel type is an important indicator, as many standards for air pollution (and more recently, goals for CO2 emissions reduction) are expressed in terms of vehicle characteristics, i.e., emissions per vehicle-km.

(ii)    Modal Intensities:  Energy use per passenger-km or tonne-km should be disaggregated by vehicle type, i.e., two-wheeler, car/van, bus, air, local and long-distance rail, subway, tram, ship or ferry for passengers; and truck, rail, ship, air for freight.  

Note:  Aggregate energy intensity for travel or freight is a meaningful summary indicator, the value of which depends on both the mix of vehicles and the energy intensities of particular types of vehicles.  The energy intensities of train and bus transportation per passenger-km are commonly 60 to 80 per cent less than the energy intensities for cars or air transportation.  For freight, rail and ship transportation are commonly 65 to 90 per cent less than the energy intensive for trucking per tonne-km. These differences between modes are of the same order of magnitude as the differences between the lowest and highest energy intensities of transportation within each mode. It should also be noted that fuel consumption per vehicle-km also depends on traffic conditions as well as vehicle characteristics. 

The energy intensity for a vehicle type depends on both capacity and capacity utilisation.  A large vehicle that is fully loaded generally has a lower energy intensity per tonne-km than a fully-loaded smaller vehicle, but a small vehicle fully loaded will have a lower energy intensity than a large vehicle with the same load.  Typical load factors for private cars are 1.5 people per car.  Typical load factors for rail and bus vary from well below 10 per cent (e.g., United States city busses on average) to over 100 per cent of nominal capacity at peak times, and in many developing countries during most of the day.  Typical load factors for trucking might be 60 to 80 per cent of weight capacity when loaded, but trucks commonly run 20 to 45 per cent of their kilometers empty, yielding a relatively low overall load factor.  Under-utilized transport capacity means more pollution and road damage (and other impacts) per unit of transport service delivered, hence capacity utilisation itself is an important indicator of sustainable transportation.  

(c)                Limitations of the Indicator:  Data availability may limit the disaggregation of the indicator to the desired level.  Considerable work is often required to disaggregate energy balances into various modes of transportation. 

Some countries’ transportation energy statistics include fuel consumed by domestic airlines or shipping lines in international transportation. Efforts should be made to exclude such transportation and energy consumption from the indicators.   

(d)               Status of the Methodology:  The methodology is in use in many developed countries. 

(e)        Alternative Definitions/Indicators:  An alternative, simpler, broad measure of energy intensity for transportation could be average fuel consumption per vehicle for all vehicles, but the results would be strongly influenced by the mix of vehicles, which varies enormously among countries and over time.  In particular, it would be influenced by the number of two- and three-wheelers.  

4.         ASSESSMENT OF THE DATA  

(a)                Data Needed to Compile the Indicator:  

(i)      Energy consumption by mode of transportation, vehicle type and fuel;

(ii)    Distance traveled by vehicles, passengers and freight, including load factors.  

(b)               National and International Data Availability and Sources:  

Energy use by fuel type in each branch of road transport, rail, ship, and air transport is published by most transport ministries in OECD countries. National energy balances (as well as present IEA/OECD Energy Statistics) do not disaggregate road transport by mode.  Few sources of energy data separate fuel consumption for rail or shipping into that for passengers and that for freight, but national or private rail and shipping organizations often do this.  Energy consumption for local electric transport (commuter rail, subways, trams) is often published separately by national authorities. 

Eurostat is a lead agency for collecting data on vehicle, passenger, and tonne-kilometers in Europe.  Ministries of Transport in the United States, Canada, Japan, Australia and other countries, often through their statistical agencies, publish similar data.  In developing countries, fewer data are available.  

(c)                Data References:  

Eurostat:  Transport Annual Statistics 

5.         AGENCIES INVOLVED IN THE DEVELOPMENT OF THE INDICATOR

(a)                Lead Agency:  The lead agency is the International Energy Agency (IEA).  

(b)               Other Contributing Organizations:  None.  

6.         REFERENCES  

(a)                Readings:  

Schipper, L. and Marie-Lilliu, C., 1999.  Carbon Dioxide Emissions from Transport in IEA countries: Recent lessons and long-term Challenges. KFB Meddelande 1999:11.  Stockholm.  

Schipper, L., Figueroa. M.J., Price, L., and Espey. M., 1993. “Mind the Gap: The Viscious Circle of measuring automobile fuel use”.  Energy Policy (October).  

Samaras. Z., et al. 1999. Study on Transport Related Parameters of the European Road Vehicle Stock.  Prepared for Eurostat and DG-7.  Thessalonikai: Laboratory of Applied Thermodynamics, Aristotle University. 

Schipper, L., and Tax, W., 1994. “Mind the Gap”. Transport Policy.  

(b)               Internet site:  IEA:  http://www.iea.org