Volvo developing all-electric long-distance heavy trucks 01 July 2013

Volvo Trucks is suggesting that electric long-distance, heavy-duty trucks, not just buses, could become a reality sooner than many think – with power lines built into the surface of the road.

Mats Alaküla, Volvo's electric vehicles expert and professor at Lund University, accepts that, apart from building the infrastructure, the challenge is about supplying the vehicle with electrical power when needed.

"In city traffic, there are currently various solutions and we are researching many others," states Alaküla.

"We have field tests in progress where our plug-in buses are equipped with a battery that can be charged quickly when the buses are at bus stops," he explains.

However, Alaküla accepts this will not work on long-distance trucks, since they stop infrequently. So, using current solutions, they would need too many batteries to be viable.

Instead, power needs to be continuously available from an external source, and Volvo is working with the Swedish Energy Agency, the Swedish Transport Administration, Vattenfall, several universities, vehicle manufacturers and suppliers to develop solutions.

Last year, for example, Volvo built a 400-metre long track at its testing facility in Hällered, outside Gothenburg, and the company has been testing the system since last autumn.

This method, currently being tested by Volvo and Alstom, entails two power lines built into the surface of the road along its entire length. A current collector, in contact with the power lines, is then located on the truck.

Alaküla explains that the lines are sectioned so that live current is only delivered to a collector mounted at the rear of, or under, the truck if an appropriate signal is detected. As an additional safety measure, the current flows only when the vehicle is moving at speeds greater than 60 km/h (37 mph).

"With this method, electric vehicles could be continuously supplied with power without carrying large batteries," states Alaküla. "The power line will be built in sections and one section is only live as the truck passes."

To make that work, the vehicle is equipped with a radio transmitter, sensed by the road segments. "If an electric vehicle passes a road segment with a proper encrypted signal, then the road will energise the segments for the vehicle."

The truck being used as a test bed for the project is a standard Volvo FH12 tractor, sporting a diesel engine. There's no electric motor installed at the moment. When the collector comes into contact with the power lines, 750 V of direct current is delivered and routed to a water-cooled heating element that has a similar power requirement to an electrically-driven truck.

Interestingly, Alaküla says the collector has been designed to track the power rails, even when the vehicle is not directly over the middle of the contact lines.

Alaküla accepts that there is still more work to do. The current collector, electric motor and the control systems required all need more R&D, he concedes.

And for the project to get off the ground, road construction, road maintenance, electricity supply along the roads and payment models all need to happen.

"A lot of years remain before this is on our roads," says Mats Alaküla, "But, if we are to succeed in creating sustainable transport systems, we must invest significantly in research now.

"I am convinced that we will find a cost-efficient way to supply electricity to vehicles in long-distance traffic and we have already come a long way."

Author
Brian Tinham

Related Companies
GE
Volvo Group UK Ltd

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