A bit strange in my opinion; Siemens announcing plans for the Highway of the Future for electric trucks, using overhead electrical wires. Why strange? Siemens has some excellent knowledge in inductive charging, a technology that is much more suitable for this application.
Trucks powered by overhead wires? Why not go induction right away?
Following is a short description on the two technologies and the reason why I think inductive is the better of the two for this highway application. The benefits of inductive are greater and the downsides of overhead wires will become too costly over time. Also, inductive technology would allow for far more users to use the same system and bring the benefits to much more vehicles than just trucks.
A trolleybus system in San Fransisco - Not really creating clear, blue skies - Wiki
This technology is better known in railway applications, either for trains or trams, in some cases trolley buses. It consists of overhead wires which cover the road sections where the vehicles are expected to drive. A mechanical pickup arm needs to be installed on top of the truck. Wile the overhead wires are a common technology and therefore relatively cheap to install, they have some limitations:
- The application is limited to trucks and similar large vehicles only; fitting such a mechanical arm on a normal passenger car and still reach the same height as the truck could cause the car to fall over.
- Due to the mechanical nature of the system, it comes with wear and tear and leads to higher maintenance costs. The benefit of the mechanical connection is a higher transfer efficiency of power, from the wire to the vehicle, but it comes at a price.
Inductive charging is in my opinion a much better solution to charge vehicles on the go. It can be adapted to fit both the large trucks Siemens is aiming at in their plans, but also the smaller cars. The technology is installed in the road and transfers the power wirelessly. Also inductive charging has some downsides:
- The technology is more expansive to install
- Inductive transfer of power comes with an additional loss, typically 70-90% of the power is transferred when compared to a wired connection.
Inductive charging allows both trucks and cars to share the same infrastructure - Link
The upsides make it very worthwhile to pursue this technology instead of the overhead wires though:
- Less maintenance, because of no wear and tear (no roadblocks due to maintenance)
- Allow other vehicles to also use this infrastructure
- No polluting of the horizon or city view as trolley buses are often seen
What is Siemens doing?
To be hones I have no idea, Siemens has a stake in both technologies, but I really think they should focus on the inductive technology in this application for the longer term. It will allow them to:
- Supply power to a larger number of users, both trucks and smaller cars
- It will allow for a cleaner place to live in, especially in cities where overhead power lines are generally considered as not pleasing to look at.
- Present something that is really futuristic and inspiring and not dredge up an old technology and present it as new and cutting edge.
I'm curious to find out why Siemens went this route. If you have any questions or comments to add to this discussion, feel free to share them.