6.4 Long distance freight trains
Freight trains differ significantly in size (number of rail cars) and use pattern. The main factors of influence on the energy consumption are the
traction type (diesel/ electric),
train length and total weight,
driving behaviour (speed and acceleration) and
Freight trains in the U.S. are on the average assumed to be longer and slower than in Europe and generally diesel trains. The main indicator for calculating energy and emission savings of rail transport is the energy consumption of the complete train, which is depending on the total weight of the train.
6.4.1 Direct energy savings for volume limited cargo
Different average energy consumption data is available which already includes the main influencing factors ([IFEU & SGKV 2002]), such as the
average annual consumption of typical freight transport of different companies,
average specific consumption of the DB (German Railways, [DB 1993]) and
calculation models for specific energy consumption of rail transport
([SCHWANHÄUSSER et al. 1986], [TEMA 2000]).
The differences are considerable, but it must be noted that even for the specific energy consumption an “… important parameter is the total train weight. The higher the weight of the train the lower is the specific energy consumption per gross ton km” [IFEU & SGKV 2002]. This may also explain the low specific energy consumption for the US freight trains which are, on the average, believed to be longer and heavier (here about ten times heavier in comparison with the freight trains studied by [SCHWANHÄUSER et al. 1990]).
There is no empirically representative “real” energy consumption data for rail transport. The specific final energy consumption of diesel and electric freight trains is very differ- ent. The influence of the different efficiencies in energy supply, however, leads to smaller differences in terms of primary energy consumption. Tab. 26 gives an overview on the specific energy consumption of different freight trains. We determine the con- sumption from typical average consumption data; additionally, important parameters for the energy consumption are considered. An important parameter is the total train weight. The higher the weight of the train the lower is the specific energy consumption per gross t-km. This dependency, as presented in [SCHWANHÄUSER et al. 1990] and [TEMA 2000], is also a result of modelling train transportation and was analysed in [IFEU 1999].