What's the future for electric car charging spots?

Listener John got in touch to ask us this question. He wonders about street lamps - and if so, whether the cables already there will have sufficient capacity. We put it to Tim Revell...

蒂姆,我喜欢这个问题a lot, but it does require me to sort of predict the future a little bit, which is not necessarily my forte. So at the moment, the UK has around about 150,000 electric vehicles and about 20,000 public charging points. But the vast majority of electric car charging happens at home and that's partly because it's slow. So if you want to charge, for example, a Nissan Leaf, which can do about 150 miles on a full charge, to charge it from nothing to completely full takes depending on your charger between 6 and 11 hours. So that is, you park at home and you plug it in and you leave it overnight. But what we are increasingly seeing is a type of charging called rapid charging, which happens almost five times the speed of the sort of charger you could get at home. So a private parking spot might not be necessary with one of these, because they could charge not just a Nissan Leaf, but a much bigger battery in less than an hour. So for example, if you're out on a long drive, it's no longer a case of just being a commuting car. You pull over at the side of the road, you have a cigarette break and a cup of tea and half an hour later your car could have another 200 miles in it. And that makes it a big difference from what we're currently experiencing a lot of now.

Chris - I was talking to Lee Cronin, who's Professor of chemistry at Glasgow, and he told me a couple of years ago that he has come up with a liquid which has got a very high energy density, and it's based on the chemical tungsten, and he can drain this chemical into say a cell, and you get the electricity out of it, depleting the liquid of its electricity. So it changes what's called the oxidation state of the tungsten, surrendering enormous amounts of electricity in the process. To recharge the cell, you drain out the depleted fluid, and put fresh one in and so he's saying that actually this might be the future of electric vehicles, where it uses exactly the same infrastructure we use at the moment for petrol stations and things. You go in and put a fluid into your car, which has got the energy in it. Difference is here, you just have to have a system that puts fresh fluid in and takes old fluid out, but basically it uses all the same way we're used to working and that might be quite attractive.

Tim - Yeah, there are lots of different ideas, I mean we had a story at New Scientist a few weeks ago about a battery that in principle, you could charge it up in 10 minutes. We had another one that could fit in your smartphone and would last five days, but the thing with all of these ideas is they're not really off the ground yet. What you need in a battery is for it to be able to work just as well at minus 20 degrees, as it does plus 30 or 40 or 50 degrees. And getting from a lab measurement where Lee Cronin's got this good idea that works in his lab to actually having something that works robustly again and again, again, in many different situations when someone's added four extra speakers to their car and done all of the things that you shouldn't do is a really, really big challenge.

Chris - So you want eight speakers, not four then, is that what you're saying?

Tim - Yeah. At least these four extra speakers from what you have now.