“Electric road,” with overhead catenary for electric trucks, begins testing in Sweden

Electric road - Swedish Transport Administration

One solution to the problem of long-range over-the-road electric trucks could be electrifying sections of roadway with a system similar to that used by railroads.

The Swedish Transport Administration recently inaugurated a two-kilometer stretch of “electric road” on the E16 highway in Sandviken. The test area is equipped with electric catenary lines over one of the lanes. The truck has a pantograph on the roof that feeds 750 VDC to the truck’s hybrid electric system. The conductor can connect automatically at speeds up to 56 mph.

The agency also plans to test an alternate technology, which involves an electric rail in the roadway, on a closed road near Arlanda. The tests will continue through 2018.

The Swedish government has set a goal of having a fossil fuel-free vehicle fleet by 2030.

“Electric roads will bring us one step closer to fossil fuel-free transports, and has the potential to achieve zero carbon dioxide emissions,” said Lena Erixon, Director General of Trafikverket, the Swedish Transport Administration. “This is one way of developing environmentally smart transports in the existing road network. It could be a good supplement to today’s road and rail network.”

 

Source: Swedish Transport Administration via Green Car Congress

  • nordlyst

    Electrifying portions of road is an interesting idea. But I wish there were some more numbers here – it’s not immediately obvious to me what would be required in terms of charging rate, total power supplied to the stretch of road, or what percentage of road would need to be thus electrified for this to function.

    So I’m trying some ballpark estimations. Let’s assume its acceptable to have the trucks slow down to 60 kph (~37 mph) for the recharging stretch of road. (This would cause a problem only if trucks were already following each other at close to minimum distance – if so, the slowdown would cause a queue to build up before the start of the charging stretch of road.) At 60 kph each truck would take two minutes to complete the two kilometers. 60 kph is 16.667 m/s, so assuming they drive a bit too closely, with just 2 seconds between the trucks, and that the average truck is about 12 meters long, we get one truck every 45 meters. Hence the maximum number of trucks to be recharged in parallel would be… a whopping 44.

    Charging power has to be very high in order to allow electrifying only a small percentage of road. Charging up to 44 trucks in parallel at a very high rate sounds like a difficult thing to do. But how much power do we ordinarily supply in this type of system? Trains have been using this sort of power supply for many decades, after all.

    According to Wikipedia, the standard TGV train, in use in France since 1982, has a peak power output of 9.3 MW. And when setting a speed record, the train – in addition to being shortened and lightened to “only” 300 metric tonnes – had a maximum power output of 19.6 MW!

    It seems plausible then that we can supply at least half a megawatt per truck even when the maximum number of trucks is using it. Is that enough?? At 60 kph, it takes two minutes to complete the two kilometers. And at half a megawatt, that replenishes about 16.5 kWh (500 kW * 2/60 hours = 500*0,033333 = 16.6667 kWh).

    How far can a heavy truck go on 16.5kWh? I really don’t know, and as always it will vary a *lot* with topography, weather, how heavy the truck is, driving style and so on. Unfortunately, for this idea to work, it’s not enough to cover the *average* use – it needs to cover pretty much the worst case scenario. I think it’s optimistic to put the worst case at 1 kWh per kilometer, but if we do, we should be able to drive 16.5 km before we’d need another two kilometers of charging road again.

    Hence, we’d be using 2 km of powered road and 16.5 km of unpowered road for a total distance of 18.5 km. So with these assumptions, we’d need to electrify 11% of the road to make it work.

    Right now I suspect the charging rate of battery packs would be one of the major difficulties in making this work. If you electrify the road it’s because you don’t want to have to have 1 MWh battery packs in your trucks. In this example we only need to carry 16.5 kWh plus a reserve (and headroom for future capacity loss), so ideally we’d like to have at most, say, 30 kWh. More pack is just more expense (and weight) if we can recharge while on the go. But a 30 kWh pack, or even a 100 kWh one, that can take half a megawatt isn’t an off the shelf product today, AFAIK (although perhaps non-li-ion batteries exist for which this isn’t a big deal?)