Overhead power lines have been installed on the side of a motorway in Sweden, permitting trucks to operate as electric vehicles. The country aims to slash freight transport greenhouse gas emissions to zero by 2030.
Stockholm. The world’s first public electric road recently opened just north of Stockholm. The two-kilometre stretch on the E16 motorway to Norway has been outfitted with overhead power lines to turn trucks into electric vehicles. Regular cars can still use the motorway.
Similar to trams
The Swedish government, truck manufacturer Scania and the German technology group Siemens have been testing specially made Scania trucks to see operate as electric vehicles when on the electrified road and as regular hybrid vehicles at other times.
Sensors on the roof of the truck recognise when the overhead power lines appear above the vehicle as it is driving. They then signal to the pantograph power collected mounted on the frame behind its cab to extend and connect to the power lines. The technology is similar to the one used by trams, but it is able to connect to and disconnect from the overhead wires while in motion. And unlike trams, which have to stay on a fixed route, the trucks are free to drive on any motorway when in hybrid mode.
Automatically switches while driving
The electricity is sent to the truck’s battery, and the hybrid mode is automatically switched to electric operation as soon as contact is made to the overhead power lines. The trucks are capable of driving at around 90 kilometres per hour while attached to the overhead lines.
When the battery if fully charged, the trucks can drive for up to one hour without having to connect to a power source. Once the battery runs out, the vehicle automatically switches back to the hybrid motor.
“With this flexible system the truck can overtake other vehicles or drive down sections without power lines,” explained Nils-Gunnar Vagstedt, who is responsible for Scania’s research in this field.
Zero fossil fuels after 2030
“We hope to be able to equip up to 100 kilometres of Swedish motorway with the overhead power lines. But that is up to the government to decide,” said Vegstedt.
There is a good reason why the test track is in Sweden. The Nordic country has set ambitious climate targets — its aim is to develop a fossil fuel independent transport sector by 2030. Today more than one third of Sweden’s carbon emissions come from the transport sector, half of which comes from freight transport.
“By far the greatest part of the goods transported in Sweden goes on the road, but only a limited part of the goods can be moved to other traffic types,” explained Anders Berndtsson from the transport ministry.
“That is why we must free the trucks from their dependence on fossil fuels, so that they can be of use also in the future. Electric roads offer this possibility and are an excellent complement to the transport system,” he said at the road’s opening.
Batteries would weigh tonnes
“This new technology will revolutionise the entire transport system in the long run,” said Sweden’s infrastructure minister Anna Johansson. According to Siemens, the electric road system is twice as efficient as internal combustion engines, making it possible to reduce energy consumption in half, cut local air pollution and save costs.
The technology is also one of the few options available at this time to electrify trucks. Unlike cars, trucks cannot easily be outfitted with batteries and stop at any charging station along the motorway to recharge.
“A loaded truck drives around 1,000 kilometres a day and is far too heavy. A strong enough battery to power a truck would weigh up to 30 tonnes,” said Vagstedt from Scania.
Scania, which belongs to the Volkswagen Group, will start testing another charging method on a bus route in Södertälje near Stockholm using wireless induction charging: energy is transferred to an electric hybrid bus at a bus stop via an installation below the road surface. A receiver mounted under the floor of the bus receives the energy and charges the roof-top mounted battery in just six to seven minutes.
“This technology has the advantage of being invisible, but it is far more expensive and could easily be damaged if installed under roads that are travelled by heavy trucks,” explained Vagstedt.