This study used data from a German pilot project to conduct a life cycle assessment of hybrid trucks that charge from an overhead line system while driving. The researchers say that by operating at full capacity with realistic technological improvements, the systems could reduce emissions by 22.1% in comparison to conventional trucks.
Heavy-duty vehicles, such as lorries and buses, account for around 6% of EU greenhouse gas emissions, and 25% of those from road transport1. While electrification of passenger vehicles is progressing steadily, equivalent advances in freight transport have not yet materialised. Electric road systems technologies, which charge vehicle batteries from an external power supply as they drive, are currently under development. This study uses data acquired directly from a pilot project in Germany to conduct a life cycle analysis of trucks using this system. In order to compare the results with conventional vehicles, the researchers also conducted a parallel assessment of conventional diesel trucks, including the manufacture of the vehicle and its ongoing use.
The ELISA eHighway system is an overhead power line on the A5 autobahn outside Frankfurt running for 10 kilometres (km), on each carriageway2. The researchers based the study on data collected in 2020, when the system was used on weekdays by five trucks for an average of seven trips each per day. The transportation service was set at 50 km, including 5 km of each trip on the eHighway. They conducted a life cycle analysis which included greenhouse gas emissions from production and installation of the infrastructure – overhead lines, crash barriers and the trucks themselves – and the ongoing use of the system. Based on the direct assessment of the pilot project, they also developed near-future scenarios for the use of a fully functional system incorporating realistic technological improvements and greater numbers of vehicles.
In the initial life cycle assessment, the researchers report that the overhead line trucks generated the equivalent of 100.7 grammes of carbon dioxide for each tonne of freight transported one kilometre (100.7 gCO2e/tkm). In comparison, the conventional truck produced 81.9 gCO2e/tkm, they say, showing that each overhead line truck created 22.9% more emissions in this pilot phase. However, they report that the emissions level for overhead line trucks reduced significantly when more trucks were used, as each was then assigned a smaller share of the overall infrastructure emissions. They say that with 18 trucks in use, the emissions would be equivalent to that of a conventional truck, and when operating at full capacity (365 trucks) this would lead to an 8.8% reduction in emissions.
The researchers also projected a near-future scenario in which realistic improvements are made in fuel consumption, battery charging rate and proportion of renewables in the energy supply (which reduces the emissions associated with charging from the overhead lines). In this scenario, they say, the overhead truck emissions are still higher than the conventional truck when only five trucks are in use. However, with 18 trucks in use they achieve an emission reduction of 13.6%, and with 365 vehicles, a 22.1% reduction.
The researchers note that the study is limited as it omits some life cycle impacts such as energy used in production processes, resource depletion and end-of-life impacts. However, they highlight the high level of detail in their life cycle analysis – especially in presenting the actual results and projected results separately – and the use of real-world data as important elements in evaluating the potential benefits of this technology. They suggest that a similar approach should be used to evaluate alternative electric road systems to establish which technology has most potential to decarbonise freight transport – and, therefore, is most suitable for further development and implementation.
Future research in this area might also consider the emissions resulting from the maintenance of traditional road infrastructure. In addition, further research could consider possible recycling and second life of the materials used for infrastructure and hybrid vehicles. The life cycle approach should consider the circularity of the materials, as we transition from a linear to a circular economy, and these materials have a high potential for recyclability and repurposing.
- The intensity of use of the pilot project does not reflect the use of a possible future commercial installation. This would be much longer than the ELISA installation – as the idea of electric road systems (ERS) is to cover significant parts of the long-haul transport in dense traffic areas (e.g. parts of Germany, Benelux, central France and northern Italy).
Hanesch, S., Schöpp, F., Göllner-Völker, L., and Schebek, L. (2022) Life Cycle Assessment of an emerging overhead line hybrid truck in short-haul pilot operation. Journal of Cleaner Production 338: 130600.
To cite this article/service:
“Science for Environment Policy”: European Commission DG Environment News Alert Service, edited by the Science Communication Unit, The University of the West of England, Bristol.
Notes on content:
The contents and views included in Science for Environment Policy are based on independent, peer reviewed research and do not necessarily reflect the position of the European Commission. Please note that this article is a summary of only one study. Other studies may come to other conclusions.
- 9 november 2022
- Keskkonna peadirektoraat