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GER values
Direct energy use
(MJ/vkm)
Indirect energy use
(MJ/vkm)
Occupancy rate
Direct energy ue
(MJ/pkm)
Indirect energy use
(MJ/pkm)
ERE value (MJ/MJ)
Total primary energy
use (MJ/pkm)
Methodology
The reduction potential of passenger transport is calculated in relative terms, resulting in a reduction percentage
per unit of transport. The unit to compare the situations in 1990 and 2050 is the transportation of one person
over a kilometre distance (pkm). This unit comes closest to the demand for transports, which is usually not
a demand for vehicle kilometres (vkm), but a demand to cover a certain distance. The magnitude of the demand
is largely influenced by the spatial settings and the activity patterns of each individual.
For a reduction potential analysis, the motorised transport demand is of importance. We discern individual and
public transportation systems. In Europe, fourteen per cent of the transport demand is covered with public
transport, 86 % with individual passenger cars (Schol and Ybema, 1998). We do not include soft modes like
walking and cycling in our analysis, as their energy use and emissions are minimised already. Information
about the overall share of soft modes in Europe is not available. Of the total mobility demand in the Netherlands
in 1994, about 10 per cent is covered with soft modes (CBS, 1995). This share is likely to be relatively
large compared to the European average, as the share of cycling is relatively large in the Netherlands.
The reference energy use in 1990 is the energy use per passenger kilometre in a passenger car. This energy use
is calculated, based on both the direct and indirect energy use of the vehicle, and the occupancy rate.
Figure 1 gives an overview of the calculation of the reference energy use. The direct energy use per vehicle
kilometre comprises fuel used for transportation and depends on engine technology, car size, etc. The indirect
energy use comprises the energy use associated with production and maintenance of the vehicle. The value of
the indirect energy use is influenced by the vehicle production energy use, the energy needed to produce car
materials (Gross energy requirement of GER value of the materials), the annual use of the vehicle and the total
lifetime. In order to convert the direct and indirect energy use per vehicle kilometre to the value per passenger
kilometre, the values are divided by the average occupancy rate of the vehicle. The next step in figure 1 is the
conversion of the direct energy use to the primary energy use. For doing so, the direct energy use is multiplied
by the energy demand for fuel winning (ERE value, or Energy Required for Energy). The goals set in the introduction
on the reduction potential needed for transportation are based on
overall reductions. The total primary energy use per passenger kilometre implies the energy requirements of all
processes associated with the use of a passenger car.
Calculating this value for the average OECD Europe passenger car and occupancy rate provides an energy use
of 0.4 MJ indirect and 1.9 MJ direct per passenger kilometre. The summed total of these two values gives a total
primary energy use of 2.3 MJ per passenger kilometre in 1990. This paper assesses the possibility of reducing
this value with 50% by 2020 to 1.2 MJ per pkm, and with 90% by 2050 to 0.2 MJ per pkm.
Figure 1 Calculating the total primary energy use per passenger kilometer
CO2 emission is directly related to energy consumption. To attribute to sustainability, reducing CO2 emission is
an important goal. The exact amount of CO2 emission can be calculated based on the total energy consumption.
However, the amount of CO2 emission per unit energy use also depends on some external factors, like the pro-