Sustainable freight transport - truck vs. train

There is a lot of discussion about what can be saved in terms of CO2 in the transport world through e-cars, the switch to public transport or the targets of reducing emissions to 95g CO2 per km for company fleets. In these discussions, however, freight transport is neglected.

The DSLV guide offers an interesting introduction. In this guide, different scenarios of CO2 emissions for trucks and goods trains with different types of electricity were calculated based on calculation principles from 2013.  We have also taken a look at the whole thing and want to go into it further here.

In logistics, emissions are divided into three different categories. The first is all emissions that occur during the production of the fuel up to its point of use. This is called well-to-tank or WTT. The second category is all emissions that occur during consumption through combustion in the engine. This is called tank-to-wheel or TTW for short. The third category is total emissions. This means that the previous values from the categories are added together. This total is called Well-to-Wheel, or WTW. As a rule, the WTW value is the one that is important and is therefore used in the following.

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Results

For a truck travelling from Munich to Berlin, it is assumed that 186 L of diesel is consumed. This corresponds to 586 kg CO2 in the entire well-to-wheel chain assuming 6.75% biodiesel. If the proportion of biodiesel were to be increased to e.g. 20% (according to volume), the emissions would be reduced to 554 kg CO2 according to the guidelines.

A significant change occurs when a goods train is used. With the electricity mix from 2013 (about 564g CO2 per kWh), 2,640kg CO2 are produced for the same distance. This means that as soon as more than 4.5 trucks are loaded, freight transport is worthwhile. With today's electricity mix, it only has to be 3 trucks. According to Allianze pro Schiene, a 740-metre goods train replaces 52 trucks.

It gets even more interesting when hydropower is used for freight transport in Germany. Because unlike in Germany, in Sweden the electricity for the railways is generated from hydropower. This means that CO2 emissions are only 4 g CO2 per kWh. In our Munich-Berlin example, the goods train would only need 18 kg of CO2. With the same amount, the driver would have to start pushing the truck all the way to Berlin after about 20 km.

In freight transport, it is common to state the emissions in g CO2 per tonne-kilometer (tkm), i.e. how much CO2 is produced to transport 1 tonne over1 kilometer. Currently, according to statistics for2019 , the emissions for truck transport are 111g CO2 per tkm and for goods trains 17g CO2 per tkm. This means that more than 6 times as much CO2 is produced for every kilometer that goods are transported by road. If we were to switch to alternatives for trains instead of the electricity mix, as in Sweden, the savings potential would be even greater.  

Logistics plays an essential role in the calculation of the Product Carbon Footprint of cradle-to-cradle or Scope 3 of the GHG Protocol. Particularly through the Product Carbon Footprint, optimisation levers can be, in addition to the selection of the means of transport, also utilisation and agreements with logistics partners on transport routes.

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Sources:

Pro-Rail Alliance