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First Fast-Charged Hybrid Bus Debuts in Umeå, Sweden with Opbrid Bůsbaar

The world’s first fast rechargeable hybrid bus is now being tested in Umeå City, Sweden in a collaboration between the companies Hybricon AB, Opbrid SL, e-Traction BV, Umeå Energi AB and the Umeå City Corporation. The “Arctic Whisper’s” batteries will be fast charged by the Opbrid Bůsbaar (earlier post) for 5-10 minutes at the end of its route to achieve nearly 100% all-electric operation but with the reliability of diesel.

The Bůsbaar—an overhead, pantograph-based fast-charging station for buses—will be located at one end of the bus route that will fast charge the bus for a few minutes at the end of each trip. This will extend the all-electric range of the e-Traction (Apeldoorn, Holland) hybrid bus from 2 hours to 18 hours. And, since this is a serial hybrid bus with a backup diesel generator, the bus can continue running on bio-diesel in case of brown-outs, traffic jams, or very cold weather.

The city’s vision is to fill Umeå’s streets with a number of these fast-charged hybrid buses by 2014, the year that Umeå will be the “Cultural Capital of Europe”.

The e-Traction converted Volvo 7700 is a battery-dominant hybrid bus; it has the ability to run on battery only, with the diesel generator turned completely off. The Arctic Whisper has 100 kWh of Valence Li-Ion batteries, typically enough for 1-3 hours of fully electric operation due to the high efficiency of the e-Traction wheel motors. With the simple addition of the Opbrid Bůsbaar fast charging station, the all-electric operation can be extended to 18 hours.

At the end of the route, the driver pulls up underneath the Opbrid Bůsbaar charging station, and the tram-like pantographs on the bus roof quickly raise up to contact the Bůsbaar. The charging process is completely automatic, with the driver never having to leave the bus. When the batteries are charged, the driver continues on as normal. The batteries are fully charged at night, with the Bůsbaar providing the additional electricity needed for a full day of electric driving.

e-Traction and Hybricon were able to convert one of their existing hybrid buses to a fast-charged hybrid in only 6 weeks. The changes that were needed were minimal: they added some additional batteries and the Opbrid pantographs, plus some electrical and software changes to accommodate fast charging. These changes converted a 100% diesel hybrid to a Fast Charged Hybrid running on nearly 100% electricity, but always with the ability to revert to diesel if necessary.

Testing of the first bus and charging station has begun and will continue through the Spring and Summer of 2011, with a second bus arriving soon.



This is very good.
You need the diesel on board in case you run out of juice.
It doesn't even have to be 100% - anything from about 50% will do.
The diesel generator makes it very flexible, though.


More questions:

  • what are the economics of this system at different fuel prices?
  • Are the overhead bus bars cheap enough to be worth installing at bus stops where the bus may only sit for 30 seconds?
  • Are there plans for commercial deployment beyond Umeå City?


This is one of the most practical application for city e-buses. Since charge stations at each end of the routes (plus an extra charge station mid-way if required) could supply 100% of the energy required, the on board APU does not have to be very large. A standard domestic type Honda generator or equivalent could do. Those small APUs are so cheap that two (2) could be installed in every PHEV city buses with negligible effects on total bus price or weight.

Roger Bedell

The economics are quite good, even compared to diesel buses. Diesel is about $8 a gallon in Sweden, while (totally CO2 free) electricity is about 20% of that. As you mention, the diesel makes it very flexible for the city and the bus system operator. If diesel drops in price then just run the bus as a hybrid. If diesel goes up, run more on grid electricity.

As to 30 second charges, the bus I ride here in Spain stops for about 5-10 seconds at most stops (I count the seconds for fun), with maybe 30 seconds at the main stops in the city during the rush times. At the route ends however, they often stop for 5-10 minutes for a smoke and to synchronize the route. Right now, prices for these big chargers (150-250kW) are quite high, but should start dropping as fast charging becomes more common for EV cars.

As to the APU, the e-Traction has a heavy industrial 60kW diesel since it was originally a serial hybrid where the diesel runs all the time. Talking to them on Monday, they thought that a lighter automotive diesel could be used in the fast charged hybrid since it runs infrequently.

After the test phase goes well (we'll post the results this summer), they want to try this system on the big 18 meter 3 axle bendy buses. They would put 4 wheel motors, on the center and rear axles. 4 wheel drive!


If battery powered buses are economical in frozen north Sweden - they are economical anywhere.

Nick Lyons

Very cool and practical--vehicles with fixed routes are made for this.


A 60 kW diesel isn't very big. VW's 2004 1.9 liter TDI engine is rated at 100 kW, and produces about 2/3 of that at 2000 RPM.


Proterra already has fully electric fast charge buses using Altairnano batteries.


..."the bus I ride here in Spain stops for about 5-10 seconds at most stops, with maybe 30 seconds at the main stops in the city during the rush times...

I'd say that buses, full of people, often stop for a minute or longer at main stops, especially when the stop is in front of traffic lights. In some cities buses only have front doors (ie Sydney).
It would be very natural to charge bus batteries during that time via overhead bus bars, even more so due to the fact that batteries are drained faster when stops are longer, as a result of higher load (more people on board). When batteries are at high charge, and stop is short, no need to rise pantograph.


I wish these guys all the best, but I am not seeing it on a large scale. The installed infrastructure is a barrier. City budgets call for bus replacement on a schedule. Light rail is done by bond measure over the long haul. When cities can replace buses with something more efficient and the payback looks good, they will consider it.

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