Saturday, November 30, 2019

An electric car economy

Recently, Brad Templeton posted a column at Forbes examining whether an electric car economy could handle peak-travel holiday loads. The major problem, of course, is that electrics have limited range at a time when, in Perry Como's words, "From Atlantic to Pacific, the traffic is terrific." So everybody is on the road and needing a recharge at the same time. In holiday traffic, you often wait in line at the pump to fill up, but with gas, that's not too much time; with a half-hour recharge, it's completely impractical.
Brad thinks it would be possible with a major build-out of recharging facilities (and it would also require a major upgrade of power generation and transmission lines). But what if that is looking at the problem backwards? What if we could reuse the current infrastructure, and do electric cars the way we do gas ones? The problem vanishes, and we could gain quite a few extra advantages.
So in the current system, you go to the service station and put 50 pounds of gasoline into the car, taking a few minutes since it has to flow in through a smallish hose. In an average car, that will get you 250 miles or so before you need to fill up again, and you'll need a rest stop long before then anyway. Why not simply have removable batteries, and pop new ones in instead of letting the car sit while you recharge the old ones? That's the way most high-powered hand tools work today, for example.
EGO system power tool batteries
There's one major problem with this for a car. The battery in a Tesla weighs 1200 pounds and when fully charged, can power it about 300 miles. You won't be "popping in" one of those.
How big a battery could you pop in? The average man can handle 50 pounds (what typical lead-acid car batteries weigh) for the few seconds it would take to take it off a service cart and onto a connector mount like the one on a power tool easily enough, and for other people a service station attendant could do it. But 50 pounds of Tesla battery would only take you 12 miles.
But those are not close to the best batteries we have. Instead of 4 pounds per mile, a lithium metal battery holds enough energy to go one mile per pound. Popping in 5 of them would get you 250 miles of range and take less time than filling with gas.
The problem, of course, is that the lithium metal battery -- it's the chemistry used in watch batteries, for example -- is not rechargeable. But so what? You're not trying to recharge it. The batteries you swap out go back to the factory to be recycled. This is just like the current car-fueling infrastructure. The service station has a supply of gas brought periodically by trucks. New batteries the same; the only difference is that the trucks go back full, of old batteries, rather than empty.
Each battery could be about the size of a briefcase; there would easily be room for ten of them under a typical car hood. You wouldn't normally drive around with it full, because less weight is more efficient; but you could load it up for the big trip. And for extra range or emergencies (e.g. the station you were counting on has run out), you could throw a few extra in the trunk.
The battery factories/recycling plants can be anywhere. Do you know where the refinery is that your gasoline comes from? They would be sited for cheap power, and maybe even intermittent power. Most people today really have no idea how cheap high-volume manufacturing processes are; recycled batteries might well be cheaper than gasoline per power provided.
One more advantage to the multiple modular battery scheme suggests itself. All the batteries don't have to be the same kind. You could have some rechargeables, some high-density, some of whatever new chemistry or new fuel cell happens to be invented next.

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