Energy efficiency

Page Last modified 19 Apr 2016
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Indicator 20: Energy and CO2 intensity

Energy intensity (and therefore CO2 intensity) of passenger and freight transport has not improved during the past three decades. Rail is the most energy-efficient mode of passenger transport. Despite improvements during the 1970s, aviation continues to be the least efficient mode. For freight transport, trucks consume significantly more energy per tonne-km than rail or ship transport.

Figure 6.2: Energy intensity of passenger and freight transport (8 EU countries)

Source: International Energy Studies, Lawrence Berkeley Laboratory, as compiled from recognised national sources


Reduce energy use per transport unit (passenger-km or tonne-km)


  • Energy intensity of passenger and freight transport, i.e. energy consumption per unit of transport activity (MJ/passenger-km and MJ/tonne-km), and by mode.
  • Fuel efficiency of new cars and of total car fleet, i.e. fuel use per km (litre/100 km)

Note: The average energy intensity of passenger and freight transport is determined by the fleet composition (number and type of vehicle), the vehicle utilisation (occupancy rates and load factors) and driving characteristics (speeds, distances).

Policy and targets

Reduction of energy (and CO2) intensity is a key measure for reducing total (fossil) energy consumption and CO2 emissions in the transport sector. The Auto-Oil Programme aims to improve the energy and emission efficiency of road transport and to improve the quality of fuels (see Group 1). A voluntary agreement with the car industry has been reached to reduce CO2 emissions from new passenger cars by 25 % (to an average of 140 g/km) from 1995 levels by 2008. The European Commission has also recently put forward a proposal for an energy-labelling scheme for new passenger cars (CEC, 1998).

However, improvements in energy efficiency lead to a decrease in the fuel price per km, which generally induces more transport use and may therefore result in increased overall energy consumption. Improvements in fuel efficiency can be further undermined by decreases in occupancy rates and load factors and by people buying larger and less fuel-efficient cars. Making full use of improvements in energy efficiency therefore requires the use of tax or other policy instruments, to avoid the improvements being counteracted by increases in vehicle-km or by the introduction of newer but heavier vehicles.

Currently, most energy policies are aimed at reducing fuel use per vehicle-km. Some EU policies (Auto-Oil Programme, Citizens' Network) and demonstration programmes (SAVE II and THERMIE) also aim, with mixed success, at boosting the shares of public transport and rail.

At the Member State level, several countries have targets for reducing fuel consumption. For example, the target in Austria is to reduce the average fuel consumption of newly registered cars by 40 % by 2010 and 60 % by 2020.


Passenger transport energy intensity

The fuel efficiency of new vehicles has improved for all modes. However, changes in the vehicle fleet (more powerful and heavier cars) and in vehicle utilisation (decreasing occupancy rates) have absorbed much of the impact in most countries. As a result, the energy intensity of road and rail passenger transport has not improved since the beginning of the 1970s (Figure 6.2). This trend is demonstrated for passenger cars in Box 6.1.

The energy efficiency of air transport improved significantly during the 1970s, mainly due to technological improvements and increasing occupancy rates, but has not changed since. Air passenger travel remains the least energy-efficient mode.

Research has also shown discrepancies between "on road" emission rates (i.e. real driving circumstances) and test emission values, resulting from poor driving behaviour, worsening traffic conditions and other problems, not generally taken into account in policy making. This emphasises the need for regular maintenance and inspection programmes (MEET, 1999).

Freight transport energy intensity
The changes in energy intensity of road freight (Figure 6.3) have different causes. The energy intensity of trucks of a given size has fallen in every country, with the increased penetration of diesels and general technical improvements in diesel or petrol trucks. But the ratio of fuel used to freight hauled has not fallen in all countries, and varies considerably between countries. With production dominated by large, international firms, the differences are not due to differences in the energy efficiency of trucks, but arise mainly from differences in fleet mix (between large, medium, and light trucks), traffic, and above all in loading and utilisation (Schipper, et al., 1997, see also Indicators 22-23)


Figure 6.3: Energy intensity of road freight transport

: International Energy Studies, Lawrence Berkeley Laboratory, as compiled from recognised national sources

The usage of trucks is also increasingly governed by the need for just-in-time deliveries, the rising value (as opposed to tonnage) of freight, and the importance of costs other than fuel cost. The potential for improving the energy efficiency of road freight transport is discussed in Box 6.2.

Box 6.1: Fuel efficiency of new cars versus energy intensity of passenger car transport

Figure a) shows how test values for the fuel efficiency of new cars have decreased over the years, mainly due to a significant decrease in the ratio of new-car fuel intensity to weight (IEA, 1997). However, much of the technology benefit has been lost by people buying heavier and more powerful cars. As a result, there has only been a slight improvement in fuel consumption for the average car fleet (Figure b). In addition, decreasing occupancy rates of passenger cars have further offset fleet improvements. So, energy use per passenger-km has not improved during recent decades (Figure c).

Figure 6.4: Fuel efficiency: and energy intensity

a) Fuel efficiency of new cars

b) Fuel efficiency of total fleet

c) Energy intensity of car passenger transport

Source: International Energy Studies, Lawrence Berkeley Laboratory, as compiled from recognised national sources

Box 6.2: Improving fuel efficiency in road freight transport

A recent OECD, ECMT, IEA workshop evaluated the potential for emission reductions through improving fuel efficiency in truck technology, changes in freight systems logistics (inter-modality, spatial organisation, traffic management) and notably behavioural and organisational improvements to reduce fuel consumption.

The key findings were that, at least in the short to medium term, the potential improvements from greater awareness of the need for energy efficiency and organisational measures outweigh the potential for technological improvements. Potential fuel efficiency improvements are estimated at about 5 % for vehicle technology improvements, 5-10 % for driver training and monitoring and more than 10 % for the other fleet management and logistics measures as a whole.

Source: OECD/ECMT, 1999

Future work

  • Harmonised EU data on energy and fuel intensity for various transport modes and vehicles is not currently available. Data from a study by the Lawrence Berkeley Laboratory on behalf of the International Energy Agency has been used instead.
  • In the long term, the joint DG Transport-Eurostat TRENDS project (drawing on COPERT methodology and MEET results - see Box 6.4) will provide data for this indicator.
  • An indicator on primary energy intensity would provide a better basis for comparing modes, mainly because it would take account of energy used for the production of electricity and fuels, and for the production and disposal of vehicles. This would, however, require extensive methodological development and data collection.
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