How does the economics of bigger batteries vs smaller batteries work in electric cars

It’s unlikely that there’ll be a major breakthrough in battery chemistry. Lithium is the lightest metal; there’s nothing better.

There are a large number of small refinements to be made, however, which have the potential for perhaps a 2-3x improvement in density. These improvements will trickle in over the years, adding a few percent at a time. We’ve seen this already, with improvements in electrolyte additives, partial silicon anodes, and so on. Not to mention advances in the physical design of the cells that increase packing density.

So in a couple of decades we’ll have a major increase, but it won’t feel like it because there was never a step change like there was with the switch to Li-Ion.

Another factor is just cost. Battery cells still cost significantly more than their material cost, and so there’s a lot of margin for improvement.

The big breakthrough will be in fuel cells.

Fuel cells are a dead end. Nobody wants to stop at at special stations to fuel their vehicle unless they have to. Being able to charge at home 95% of the time is a fantastic thing. Further improvements to range and charge time will solve the remaining concerns about electrics.

And that’s without the chicken-and-egg problem in the way of fuel cells. Even in hippy-dippy CA, we have like 20 hydrogen stations. No one wants to pay for them, and they’re the only place to get hydrogen. It’s not like an electric where you still have a 110 outlet as a last resort even when nothing else is nearby. Even a die-hard greenie willing to make big sacrifices can’t put up with a fuel cell vehicle unless they happen to have a station nearby.

I’ve seen carbon nanotube technology credited with the potential for a 10X increase in density:

http://nanomagazine.co.uk/index.php?option=com_content&view=article&id=1160:carbon-nanotube-technology-produces-up-to-tenfold-increase-in-lithium-ion-battery-power

Lithium-air is also proposed to have a 10X improvement potential:

Lithium-sulfur is generally in the 2-3X range, but I’ve seen some claims of up to 5X (potential).

It’s probably unlikely that we’ll achieve the maximum potential but, then again, with multiple paths to significant gains, there may be some combination of the different methods that achieves an even better result than the best of any one technique.

(This is all speculative, of course.)

That’s the point.
Fuel cells that can use gasoline will revolutionize electric cars.

I intentionally de-rated my figure to account for optimism :). I’ll agree that one can’t yet rule out a 10x gain, but there are very significant obstacles in the way. Early claims on silicon anodes were also in the ballpark of 5-10x improvement, but as of yet we’ve seen more like 10%. Tesla is using this chemistry now, but as of yet they can only add small amounts of silicon, limiting the potential.

I expect the same thing to be true of the other advancements. They’ll find a way to add silicon nanowires, but only in small quantities, leading to a modest improvement, and they’ll never reach the theoretical maximum.

Now I really don’t understand. You end up with a car that still emits CO2, still requires going to gas stations, still funds instability in the Middle East, costs more than the equivalent ICE, and is probably no more efficient than a strong hybrid. It’s the worst of all worlds.

Well then try methanol for your fuel cell. Made from crops, so by definition carbon neutral, can be grown anywhere there’s sun and water, so you can support/deny support to your regime of choice, and – going to a refueling station is what’s good about using a liquid fuel: at the specific energy density of methanol (20 MJ/kg) and with a typical fuel pump rate of 10 gal/min you are transferring energy to your car at a rate of about 10 megawatts. It’s hard to imagine any electrical charging system designed to be safely operated by a typical careless 16-year-old n00b ever approaching that kind of rapid recharge rate. That’s a scary amount of electricity.

Additionally, when you imagine the infrastructure challenges, a typical tanker truck bringing 9000 gallons once a day to a service station represents a continuous (24/7) average power transfer rate of 6 MW, which if delivered directly by a 22kV distribution line would require a continuous delivery of 280 amps, around the clock. That’s a lot of power. If you imagine replicating the power distribution system represented by the current distribution system of gasoline with, instead, electricity, you need lots more high-voltage electric lines, an enormous infrastructure build-out. The total amount of energy used in transportation in the United States, obtained almost entirely by direct combustion, is about equal to the total amount of electricity produced – so you need to approximately double the overall electrical generating and distribution capacity.

You also have some interesting problems to do with demand variation, since one of the valuable facts about liquid fuels is that you can store the energy pretty much anywhere for very low cost by just letting it sit there in a big cheap steel tank. Storing electricity, particularly very large amounts of it, requires heavy, expensive, and specialized machinery (e.g. gigantic banks of batteries). If you don’t store the power, then you have issues of getting it where it’s needed, when it’s needed, pretty much instantly, and will have a real logistical headache matching up your power generators’ output with your power consumers’ demand, moment by moment.

None of these problems have been seriously addressed yet, because electric car usage is presently such a tiny fraction of the total transportation energy use, or of electrical energy use, that they don’t really matter. But if everyone started driving an electric car, they would be, and they are not trivial or cheap to solve.

methanol is incredibly toxic.

I think that fear is way overblown. I live in the south, and in the summer my house air conditioner can use 2,000 kWh in a month. Meanwhile my electric car uses just a little over 10% of that.

If we were able to build out the electric grid and production to handle air conditioners 60 years ago, I’d think we’d be able to accommodate EVs that use much less.

If I understand he technology correctly, flow batteries will allow electrical energy to be stored in fluids. Very corrosive fluids, admittedly, but still better than huge banks of batteries.

It’s liquid fuels that can’t be made safe. Gasoline fires happen all the time, because people are stupid and it’s hard to put in effective safety protections compatible with existing vehicles. On the other hand, even several hundred kilowatts can be made safe through physical locks, electrical cutoffs, and so on. No one has been injured electrically by a Tesla Supercharger (there have been some fires due to malfunctions, but again no injuries).

That would indeed be crazy, but has no relation to reality. Most charging happens at home, and at night when the grid is at its lowest usage. You seem unable to see past the service station model. It’s not going to work that way. Unlike liquid fuel distribution, chargers can be put anywhere and everywhere. We’ll only have dedicated charging stations along the most desolate, uninhabited routes.