Saturday, 14 April 2018

Eroadarlanda / Elways / Electric charging road in Sweden

What is it?

The world's first electric charging road "opens**" in Sweden. Near Arlanda airport. It can "charge***" "electric" cars while they are driving.
It is a massive press-release that appears to have hit a lot of mainstream media in the last couple of days (12 April 2018)

"Stretch of road outside Stockholm transfers energy from two tracks of rail in the road, recharging the batteries of electric cars and trucks"

They certainly seem to have an excellent PR agency.

Can it do what it says?

 Mostly, no.

They have a truck which apparently can run from this scalextric-type road. It is not clear whether the truck is electric. The truck is electric. Most of the video I can find shows a diesel truck with a dummy electrical load. They also have a test-car (which is, I suspect, petrol-powered, at least it sounds like it in the video) which carries a 17kw dummy load powered from the track. It is not clear whether the car is road-legal with the dummy load (I can only find video of the car being used on a test-track)

Could it possibly work, ever?

Maybe, yes. If it can actually deliver 17kw to a moving vehicle, that is approximately enough to run a car at motorway-type speed and charge at a modest rate simultaneously. 

They made various claims about its safety and robustness etc, which seem at least vaguely plausible. They obviously did some testing in various conditions. There is video of the truck driving in snow.

So what's the problem?

No normal electric car could ever charge from the track while driving. The electrics system would have to undergo major modifications. That's ignoring the major software updates.

That's to say - EVs can recharge while driving - it's called regenerative braking. 

The electric system in an electric car is fairly complex and needs to handle a lot of power in several directions. Most electric cars can charge at up to 50kw, and many will discharge even faster in some conditions. Moreover, they can switch from one to the other in a very short time while driving.

EVs usually have an onboard charger for charging from AC (Level 1 and 2) sources. This is part of the power electrics which can't operate at the same time as the drive.

Rapid charging (Level 3) is done by an external charger, which communicates with the car in a rather complex way, and provides DC at the correct voltage / current for the specific charging requirements of the vehicle. The external charger is a big heavy box which would be prohibitively heavy to put on a light vehicle. They usually take an industrial 3-phase supply.

I don't think it's plausible to use a level 3 charger in the track:
  • There aren't enough pins for a level 3 charger, which needs at least an AC supply AND a DC supply.
  • There would not be time on a 50m section (or even 200m section) of track, for the charger to get the correct voltage, current etc for the specific vehicle
  • The large number of complex level 3 charger boxes would be prohibitively expensive.

There is a lot of difference between delivering some power to the vehicle (which has been demonstrated) and charging an EV traction battery (which has not).

But those things could be solved?

Yes, in principle, but no car maker is going to want to do that. Modern vehicles are not designed for a single market, it's not cost-effective. Cars designed now (without elways support) are going to continue to be made for 20 years without a major redesign of their drive train.

It's not remotely viable to redesign the electrics of an EV for a feature which is available only in one country, as the weight / performance / space penalty would exist in the design everywhere else.

Why else am I sceptical?

 Most of the videos that I've seen seem to be on the test-track (not on the airport highway). I saw one 12-second clip which appears to show a slightly less hacky pickup (maybe on an electric truck) looking like it might be powering the real truck.  But otherwise, all the media seem to be from the test-track, or with dummy loads.

The Guardian's funky video obviously shows a diesel truck with the test-load running some bright lights - this is presumably on the test-track because it won't be road-legal.

The PR is certainly very strong. There is a lot of marketing wank that makes very big promises, but is very light on details.

There is basically no detail whatsoever about any of the vehicles that they have to use on this "open" road.  I understood from the various press releases that there was one truck which would be regularly using the road, which is a 2km section. Again, it's not clear whether the truck actually takes useful traction power from the road (whether charging or just driving), or just drives a dummy load.

* I wish they would spend more money on developing the tech instead of making mockup videos and writing PR stuff

 Anything positive?

Yes a few things
  • The tech for getting the track and pickup working seems well developed, they've shown it working back in 2013
  • It has been demonstrated working in bad weather.
  • If we forget about charging electric cars and just consider an extra power system for (ICE powered) commercial vehicles, it starts looking a lot more sensible.
  • Heavier, slower vehicles pay a lower weight and aerodynamics penalty for having the tech installed.
  • Delivering 17kw to an electric motor on an otherwise-diesel truck would save it a great deal of fuel, it would also extend the range of an electric one (but not much if you only have 2km)

** opens to the single vehicle it's designed to work with. But other traffic can still use the road, so I suppose that's open?
***  well, not actually charge. But deliver power to. Perhaps?

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