Cost-effective operation of trucks powered by overhead lines is possible – but there are hurdles to overcome

May 08, 2017

Pilot projects are starting worldwide that feature trucks powered by overhead lines. The Fraunhofer Institute for Systems and Innovation Research ISI has analyzed the opportunities and challenges associated with this technology together with four research partners. The report compiled on behalf of the German Federal Ministry of Transport “Machbarkeitsstudie zur Ermittlung der Potentiale des Hybrid-Oberleitungs-Lkw” (Feasibility study to determine the potentials of overhead line hybrid trucks) shows that hybrid trucks operated using overhead lines can be cost-effective, but that several obstacles concerning infrastructure and acceptance have to be overcome first.

Road freight transport is responsible for about one third of the CO2 emissions from road traffic. Trucks powered by overhead lines are one possible option to achieve decarbonization here: The study concludes that these trucks can be cost-effective in a mass market – if the overhead infrastructure is well developed and utilized.

Due to their higher efficiency compared to diesel trucks, the trucks powered by overhead lines can make a decisive contribution to reducing greenhouse gas emissions in the strongly growing road freight transport sector if mainly renewable energy sources are used to power them. The project coordinator, Professor Martin Wietschel from Fraunhofer ISI, sums up: “Only 4,000 to 5,000 kilometers of the most frequently used highways would have to be fitted with overhead lines. The necessary investments of eight to twelve billion euros are not particularly high compared to the construction costs of other infrastructures.“

State pre-financing needed for overhead lines

However, there are several significant obstacles to the introduction: According to the study, above all, the overhead line infrastructure - that makes a loss to start with - would have to be pre-financed, probably with state funds. The period during which infrastructure can be developed is still open. Because substantial numbers of foreign semi-trailers also use Germany’s highways, the authors recommend pursuing a European solution to improve infrastructure capacity utilization and harmonize European transport policy.

Another hurdle is the currently still limited acceptance of truck manufacturers, who would have to reorganize their product portfolio and could lose parts of their value added with the internal combustion engines. Logistic companies are also affected which may experience a loss of flexibility in dispatch planning. It is also still unclear how residents and users would deal with the visibility impairments and visual impacts, for example.

However, Martin Wietschel also mentions the need for further research: “The new propulsion systems for heavy-duty trucks, especially with overhead lines, raise the question of how to integrate them into the energy system: They require very large amounts of power and it is very difficult to shift this electricity demand from an energy economics perspective, for example, to times with high renewable power shares in the energy system.“

For the study, the hybrid trucks powered by overhead lines were also evaluated in comparison to other new electricity-based fuels to decarbonize long-distance road freight traffic. It emerged that fuel cell trucks with hydrogen are also an interesting option, among other reasons, because of their efficiency advantages compared to other electricity-based fuels like methanol. Further studies are needed on which option should be preferred in the future.

The report “Machbarkeitsstudiezur Ermittlung der Potentiale des Hybrid-Oberleitungs-Lkw“ was produced as part of the scientific advice concerning the mobility and fuels strategy given to the Federal Ministry of Transport and Digital Infrastructure (BMVI). Also involved apart from Fraunhofer ISI were Fraunhofer IML, PTV Transport Consult GmbH, TU Hamburg-Harburg – IUE (Hamburg University of Technology – Institute of Environmental Technology and Energy Economics) and M-Five.

The Fraunhofer Institute for Systems and Innovation Research ISI analyzes the origins and impacts of innovations. We research the short- and long-term developments of innovation processes and the impacts of new technologies and services on society. On this basis, we are able to provide our clients from industry, politics and science with recommendations for action and perspectives for key decisions. Our expertise is founded on our scientific competence as well as an interdisciplinary and systemic research approach.