Highways where vehicles are powered by electricity from the roadway may sound like science fiction today. But for Scania, electromobility is one of various development paths that must be investigated, writes Nils-Gunnar Vågstedt, PhD in vehicle engineering and head of hybrid system development at Scania.
Fossil fuels are a finite resource that adversely affects the environment, among other things by releasing climate-changing carbon dioxide during combustion. It will thus be necessary to find other energy sources for vehicle propulsion in the future. Another issue is achieving the most efficient possible energy utilisation.
One attractive alternative that Scania is investigating is vehicles powered by electricity, under the concept name “electromobility”. If this electricity is sustainably generated, it reduces environmental impact. Meanwhile it boosts energy efficiency, since an electric motor has more than twice the efficiency of a combustion engine.
Today electric-powered cars are already on the roads, often in the form of hybrid cars that combine electric propulsion with a combustion engine. Testing is also underway on hybrid propulsion for commercial vehicles. For short distances, this includes plug-in solutions where a vehicle is charged by being connected to the electric power grid. But when it comes to long-haul heavy vehicles, developments in electric propulsion have not progressed equally far.
The main reason is that both hybrid and plug-in solutions require batteries that − with today’s technology − are far too heavy, bulky and expensive. Due to the difference in energy density, every kilo of diesel fuel must be replaced by a hundred kilos of batteries. This dramatically reduces payload capacity.
One solution to the weight problem in heavy vehicles is to supply electricity continuously during a journey by electrifying highways. If power can be transferred from the roadway, vehicles of different types and sizes − including cars − can utilise the same power supply infrastructure.
There is a big difference between this and a railway, which runs on electricity via overhead lines, requires centrally controlled traffic and is limited to a certain type of vehicle. Electrification of the road network seems a logical step in modernising our infrastructure.
Electrifying the highway network in Europe will require close and extensive collaboration between countries in order to develop a common standard. One important element of this work will be to retain the flexibility of the network, so that all vehicles can use it at the same time as it is both robust and safe. Scania would like to see a free, open market but currently has no opinion on the matter except that this is worth further investigation. Together with Volvo Powertrain, Bombardier and other companies in the transport field, Scania has applied for project funding from the FFI programme − a partnership between the Swedish government and the automotive industry for research, innovation and development that focuses on climate, environment and safety − for a study concerning electric road transport vehicles.
If it proves to be a feasible alternative, induction looks like an interesting method for transferring electricity from roadway to vehicle. Induction is an electromagnetic phenomenon that makes it possible to transfer electric energy to a vehicle without direct electric contact with the road surface. Compared to fixed transfer, using a direct contact with the roadway, this will allow flexibility, safety and the potential to deal with snow and ice.
Another solution to the weight problem would be to develop lighter batteries, but this would require some sort of technological leap that is not currently foreseeable. Even if the use of batteries at present seems to be a dead end for long-haulage transport, it is still too early to commit ourselves to one given solution. No one can say whether any of today’s main development paths will be viable forty years from now. This is why Scania will continue gathering knowledge about all possible forms of propulsion for heavy vehicles. Regardless of which technology that dominates for trucks, buses and coaches in 2050, Scania’s ambition is to remain a market-leading manufacturer.
Advantages of electrified highways
- Reduces environmental impact
- Energy-efficient: an electric motor has more than twice the thermal efficiency of a combustion engine
- First green alternative for long-haulage transport
- No need for heavy batteries onboard thanks to continuous supply of electricity