The energy transition poses particularly great challenges for road freight transport. A tendency towards further increasing transport services meets a set of alternative courses of action, all of which entail considerable practical disadvantages - be it poor energy efficiency in the case of synthetic fuels and hydrogen, high weight and high costs in the case of battery-electric vehicles or the required infrastructure in the case of overhead line trucks. Nevertheless, there is no way around a move away from fossil fuels - and batteries play a decisive role in almost all options for action.



Relevance of this field of application

Freight transport by road contributes significantly to anthropogenic greenhouse gas emissions: As the third largest polluter in Germany, the transport sector is responsible for a total of about 20 % of emissions; more than a third of this is accounted for by heavy goods vehicles (HGVs) and commercial vehicles.1 It is true that specific pollutant emissions per tonne-kilometre have been significantly reduced in recent decades through improvements in engines, exhaust technology and fuel quality. Nevertheless, CO2 emissions have increased by 22% between 1995 and 2018 due to a sharp rise in tonne-kilometres (by 74% between 1991 and 2017).1,2 The number of trucks in Germany in 2019 was around 3.4 million, an increase of 39% compared to 2008. In addition, there are 2.3 million tractor units, of which 224,000 are semitrailer tractors.3,4

The situation in Europe is similar: Here, the energy demand of the transport sector increased by 30 % between 1990 and 2015. Around one third of Europe's final energy consumption was in the transport sector in 2016, three quarters of which was in road transport. GHG emissions increased by 18% between 1990 and 2016.5

It is not only because of the climate-damaging trends outlined above that freight transport poses particular challenges for the energy transition. HGVs transport much larger masses and therefore consume significantly more energy per kilometre travelled than passenger cars. In addition, they often cover longer distances. Both of these factors are reflected in a high demand for energy carriers to be carried. Regeneratively produced liquid fuels or hydrogen are relatively easy to transport, but have poor energy efficiency. Although purely battery-electric trucks appear to be advantageous in terms of energy efficiency, with currently available batteries they would weigh several tonnes more and at the same time have a significantly reduced range compared to a conventional diesel drive. Against this background, overhead line trucks (O-trucks) have recently been increasingly discussed.6

Road transport will remain the dominant transport medium for goods for the foreseeable future. Even if the shift potential to rail and inland waterways is fully exploited, 54 % of the transport performance will still be accounted for by trucks in 2050.7


1 Bundesministerium für Umwelt, Naturschutz und nukleare Sicherheit (BMU) (2020): Klimaschutz in Zahlen – Fakten, Trends und Impulse deutscher Klimapolitik.
Link ↗ (accessed 26.01.2021).

2 Umweltbundesamt (UBA) (2020a): Emissionen des Verkehrs.
Link ↗ (accessed 26.01.2021).

3 Bundesministerium für Verkehr und digitale Infrastruktur (BMVI) (2021): Fahrzeugbestand.
Link ↗ (accessed 26.01.2021).

4Umweltbundesamt (UBA) (2020b): Verkehrsinfrastruktur und Fahrzeugbestand.
Link ↗ (accessed 26.01.2021).

5 Hacker, Florian; Mottschall, Moritz et al. (2020): National and EU freight transport strategies - Status quo and perspectives and implications for the introduction of electric road systems (ERS).
Link ↗ (accessed 26.01.2021).

6 Hacker, Florian; Blanck, Ruth et al. (2020): StratON – Bewertung und Einführungsstrategien für oberleitungsgebundene schwere Nutzfahrzeuge.
Link ↗ (accessed 26.01.2021).

Use of battery storage

Battery storage is needed in all electric truck drives. There are major differences, especially with regard to dimensioning: With regard to purely battery-electric trucks, it is assumed that batteries with capacities in the range of 600 kWh are needed, which corresponds to an additional weight of 2-3 t and acquisition costs of about 100,000 €.7 The range achievable with one battery charge is about 400 km. This is considerably less than the range of a diesel truck with one tank of fuel. However, a large proportion of trucks actually drive shorter distances: The average distance for national transports in Germany is around 90 km, for international transports from Germany a good 300 km (EU average around 90 and just under 600 km respectively).6 According to calculations by the European Automobile Association, around 85% of all HGVs in the EU drive shorter distances than 150 kilometres.8

In hydrogen fuel cell trucks, the fuel is refuelled as a highly compressed or liquefied gas and used to generate electricity by means of a fuel cell on board. According to pilot projects, the associated battery is relatively small, at 70 kWh, as it is only switched on during energy-intensive driving phases such as overtaking manoeuvres.9 However, the efficiency of hydrogen propulsion, at 31 %, is considerably lower than that of battery-electric or overhead line trucks (O-trucks), at 73 %.7

The latter have therefore recently been seen as an option worth considering for the energy transition in road freight transport. The vehicle is powered by electricity from an overhead line, and a battery is charged at the same time. This enables shorter journeys - for example from the haulage company to the overhead line route - without a connection to the power grid. The advantages are that no downtime is required for charging and relatively small batteries (175 kWh capacity is calculated) are sufficient. The prerequisite, of course, is the development of a corresponding infrastructure. A model study recommends the construction of an overhead line network over a third of the German motorway network (4,000 km), the costs of which amount to around 12 billion euros and could be financed by tolls.7

7 Öko-Institut et al. (2020): Treibhausgasminderung im Straßengüterverkehr – Oberleitungs-Lkw als möglicher Teil der Lösung. Erkenntnisse und Handlungsempfehlungen aus dem Projekt StratONund weiteren aktuellen Forschungsarbeiten.
Link ↗ (accessed 27.01.2021).

8 Rueter, Gero (2020): Klimaschutz: Strom für Bus und LKW. Deutsche Welle (DW).
Link ↗ (accessed 27.01.2021).

9 Daimler Truck AG (2020): Technologiestrategie für Elektrifizierung: Weltpremiere des Mercedes-Benz Brennstoffzellen-Konzept-Lkw.
Link ↗ (accessed 27.01.2021).

Performance requirements

To protect the driver, the vehicle and the load, the batteries used must meet high safety requirements. Flammability and the risk of explosion should be excluded as far as possible, especially since battery fires are very difficult to extinguish. In addition, the battery storage systems must have a particularly good environmental balance. The purpose of the energy transition in the transport sector is primarily to reduce the negative environmental impacts of current vehicle technologies. The advantage of electric drive technologies would be difficult to convey if they were accompanied by different but equally serious environmental damage.

In the area of functionality, fast-charging capability is of crucial importance. Especially in the case of purely battery-electric vehicles, this could alleviate or even eliminate the problem of the low range in practice. Last but not least, high demands are also placed on the cycle stability of the batteries used. This has an impact on the service life and thus the investment security.

Market outlook

Road freight transport continues to grow and at the same time is forced to completely change its energy supply from fossil fuels to regenerative sources within a few decades. According to the German government, as early as 2030 around one third of the mileage in heavy road freight transport will be based on electric drives or electricity-based fuels.1 Even if synthetic liquid fuels play a prominent role in the political discussion so far, an enormous demand for battery storage is to be expected: Synthetic fuels have the worst efficiencies, and all other options (battery-electric, overhead line or fuel cell drives) require batteries.

If by 2030 one third of the German truck and articulated lorry fleet had the required alternative drive systems, and if only 10 % of these were fuel cell or overhead line powered and 0 % purely battery electric, this would amount to over 120,000 vehicles. Assuming an average battery capacity of 120 kWh, more than 14 GWh would be required in Germany in the next ten years alone.