Is there an e-Autobahn in our future?

Posted Friday, 25 September 2015, 12:29

In the small town of Templin, Germany one hour north of Berlin, on the site of an old Soviet airfield, Siemens engineers are hard at work on what could be the future of low-carbon freight transport. Driving onto an unnamed road leading into the old airbase you pass by countless rows of solar panels, a summer hotel for bats (yes, really), finally reaching a long taxiway used by Russian jets decades ago. This is the home of the Siemens e-highway research test site. The old taxiway has been transformed into a prototype highway of the future.

Siemens truck

At first sight, the 2 kilometers of roadway look very much like a typical highway. But suspended 5 meters above the road surface is a continuous line of cables strung from protruding arms mounted on evenly spaced poles installed along the side of the road (it’s called a catenary system). The next thing you notice, driving down the road at highway speeds, is a full-scale Scania tractor-trailer beneath the cables—fully powered by electricity.

This is how the technology works. A typical diesel-electric hybrid truck (or any heavy truck equipped with an electric drive motor plus a second power source, for that matter) is fitted with a specially designed pantograph. The pantograph, which is in the form of an arm extending from the roof of the truck, works in the exact same way as those used in electrically powered trains and trams: it consistently delivers voltage from power lines overhead to keep the electric motor fully activated. However, trucks on the road need more flexibility than those trains and trams, and that's where Siemens' innovation comes in. The pantographs on these trucks have a number of special features. The most noticeable is that the pantograph is fully retractable; when a truck needs to change lanes, or exit the highway, the pantograph disengages from the cables and folds back into its compartment on top of the roof. At that point, the vehicle switches from electric power back to power supplied directly from the vehicle—a conventional diesel engine in this case.

Mile for mile, running on electricity is significantly more efficient on a well-to-wheel basis than running on diesel (77% vs 32% well-to-wheel efficiency for electric road systems vs. conventional diesel power). And if the source of the electricity is both clean and renewable, the CO2 benefits could be even more substantial—perhaps even carbon neutral. Countries and regions around the world are developing plans and commitments to decarbonize their transportation sectors, and the question of how that will be accomplished looms large for the freight segment. Most forecasts predict the diesel engine will continue to dominate for many years to come. Although there is certainly significant potential to improve the efficiency of a conventional diesel engine, there is a theoretical limit—which means you can’t virtually decarbonize your freight sector while simultaneously relying on diesel power.

The Siemens e-highway gives us a glimpse of a potential pathway whereby the use of diesel power could be systematically phased out rather than abruptly discontinued. The more miles of roadway covered by the catenary system, the less amount of time the trucks would need to be running their diesel engines (and the faster the system would pay for itself through fuel savings). Of course, there is a significant challenge associated with building up the infrastructure from nothing to 100% coverage. The strategy that Siemens is proposing is to first focus on the most heavily trafficked freight corridors in a given mega-city or region. For example, in the Los Angeles metropolitan area there is a strip of roadway connecting the ports of Los Angeles and Long Beach to a nearby rail yard. The rail yard currently handles approximately 750,000 containers per year, but forecasted development around that location will enable the handling of 2.6 million containers annually in the next few years. Siemens is taking their e-highway test project from the closed track in Templin, Germany, to the heavily traveled roads of Los Angeles, California. They have started construction on a demonstration project to electrify 1.5 km of that port-to-rail strip of roadway and within the next year will deploy a number of test trucks to prove the concept can work in real LA driving conditions. We will be keeping tabs on this project and plan to visit the site once it is up and running—although we doubt they will have a bat hotel.