The growing demand for transport will increase road freight emissions from 1.1 Gigatons (Gt) of CO2 in 2010 to 4.5 Gt by 2050, according to the International Transport Forum (ITF). The ITF predicts emissions from surface freight transport to overtake those from surface passenger transport in the period up to 2050. See References. It is therefore imperative to curb emissions caused by road freight transport if climate goals are to be achieved.
Road freight is anticipated to remain a large and vital part of the transport system. Solutions to improve its efficiency and performance are therefore essential, as over 95% of it presently uses fossil fuel.
Given that several countries already have very low carbon footprint for electricity and that global electricity generation will need to decarbonize over the coming decades as part of climate mitigation measures, it makes sense to further the use of electricity for freight transport. This also guaranties immediate benefits such as improved local air quality, fuel diversification and increased energy efficiency as well as reduced operating costs (from both fuel and maintenance compared to Internal Combustion engines, ICEs).
However there are significant challenges to this and the eHighway project has been developed by Siemens to overcome these.
The eHighway-System consists of an overhead contact line (catenary) infrastructure as well as trucks equipped with current collectors (pantographs) and hybrid drives, see Fig. 1. This is similar to the catenary systems used in providing electricity to trains, trams and trolleybuses. Thus it combines the advantages of proven technologies from rail and road systems and is an open, scalable and reliable system for electrified road transport. The system is designed so that existing roads can easily be upgraded, without interfering with the road infrastructure and its conventional users. When connected to the contact line the eHighway-adapted trucks use an electric engine to fully power its operations. The trucks are also configured to have alternative means of propulsion when overtaking or driving on non-electrified routes. The eHighway concept can flexibly be combined with conventional ICEs or zero emission
Fig. 1: The eHighway with its sub-systems.
The key component of the system, which allows the fully electric operation of the eHighway trucks is the newly developed pantograph. It assures the safety during connecting and disconnecting with the overhead contact line in the speed range of 0 to 90 km/h. Furthermore the pantograph actively compensates for the vehicles’ lateral movements within the lane by using a system of sensors and actuators. These are small electric motors that move the pantograph to ensure it stays in contact with catenary.
The first eHighway demonstration track was built near Berlin, Germany, on a private road, as part of the ENUBA project, funded by the German Ministry of Environment (BMUB) in 2011. The overhead contact line infrastructure was erected alongside the road, and has no direct interference with the road itself, see Fig. 2. Consequently the infrastructure does not impact the movements of other traffic so has no negative implications to mixed operation on the road.
Compared to conventional diesel-operated trucks, the eHighway-Systems can double the energy efficiency in truck operation and offer the opportunity to utilize renewable power instead of fossil fuels for heavy road freight transport.
Fig. 2: 2 km long demonstration track near Berlin
The proven technology of the eHighway-System minimizes disruption during installation, operation, and maintenance of the infrastructure and its overall lifetime cost can be kept low and stable.
In collaboration with the Technical University of Dresden and the Federal German Highway Research Institute (BASt), various types of traffic- and road-specific challenges have been analyzed. This research examined many different safety issues as well as the adjustment of the electrification infrastructure to a wide range of road conditions such as bridges and gantries.
The Berlin track project is being followed by demonstration projects on public roads. One is on-going in Sweden, in cooperation with Scania funded by Trafikverket and other authorities. Another near Los Angeles, USA, in developed in cooperation with vehicle partners such as Volvo, funded by the South Coast Air Quality Management District.
This solution shows promising results for shifting freight transport to e-mobility, via hybrid vehicles. In addition to providing highly promising results in terms of technology, the tests of the eHighway-System also demonstrated benefits to the environment and economy:
- As for all transport systems one of the most important characteristic values is the energy consumption, the eHighway benefits from a high system efficiency ranging from 80 – 85 % from the in-feed at the substation to the wheel on the trucks.
- Additional benefits result from the ability of eHighway-trucks to recuperate energy while braking or cruising down-hill.
- Above the improved air quality achieved by eliminating local emissions, the demonstrated efficiency gains of the electrification of the road freight transport can also translate into global reductions of CO2.
- As power generation decarbonizes, the eHighway-System allows those gains also to bring down the emissions associated with heavy duty road freight.
- An analysis by BMUB showed that a system installed on only the busiest parts of the German highway network would be able to address ca. 60% of all the emissions from heavy duty road freight.
Potential for scaling up
The above mentioned public demonstrations will help to show both the ecological and the economic benefits of the eHighway-System and may lead to an extension of the electrification infrastructure.
Near term applications are shuttle routes characterized by a high volume of transport and that will also widely use the infrastructure. This will deliver significant air and GHG benefits due to the intensity of traffic. The efficiency of the system furthermore generates economic benefits. This development path is the same as was taken by rail electrification almost a century ago.
There are two enabling policies, which can be executed in parallel. One is to support the pilot projects for shuttle operations, examples include linking ports and logistics centers or to be used for mining transport. The other is to expand the already extensive body of knowledge (e.g. reports by BMUB, BASt, Trafikverket) to address local technical concerns as well as estimating the potential impact from environmental and economic perspectives on national and international highway operations.
OECD/ITF (2015), ITF Transport Outlook 2015, OECD Publishing, Paris/ITF, Paris. DOI: http://dx.doi.org/10.1787/9789282107782-en.