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Comment by sgrove | Hacker News Reader

I'm curious what the total energy storage would be, and what kind of destructive damage it could do. A million miles is a lot of miles to move a full Tesla, passengers, and luggage around.

Anyone want to do a back-of-the-envelope sketch and give some colorful units-of-measurement given instantaneous discharge (e.g. tons of TNT)?

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Assuming 500 watt hours per mile for Cybertruck (likely the first Tesla vehicle using it), a million miles is 1.8e19 ergs.

1 kiloton TNT is 4.184e19 ergs.

Million mile battery is 0.43 kilotons TNT, about 1/35th of a Davey Crockett man-portable nuke.

Well, a more reasonable value for a tesla is 300 wh/mi, and a tesla could pull off 1,000,000 miles of range with a mere 12.91 gm of plutonium.

If the the cybertruck really needed 500 wh/mi, it would require a bigger million-mile battery - say 21.53 gm of plutonium.

But you know the environmental folks would complain bitterly, so maybe tesla should offer a "green" cybertruck option with a heavier 22.66 gm thorium battery. It will probably require retuning the suspension for the extra weight.

https://en.wikipedia.org/wiki/Energy_capacity

Just have to efficiently & compactly convert thorium to electricity at a suitable rate in a sub-1000 lb package priced under $65,000 (cost of battery + 500,000 kWh).

I picked 500Wh/mi because Cybertruck will likely be first to use the new batteries, and will require more power than the cars/SUVs.

Based on this[0] thread on the Tesla forum, I'll use 0.31 KWHr/mile. If that's the case, a million mile battery would be equivalent to 267 tons of TNT.

[0] https://forums.tesla.com/forum/forums/miles-kwh [1] https://www.wolframalpha.com/input/?i=%280.31+KWHr%2Fmile*1+...

Dividing 1000000 miles by the up-to 390 mile range of the 100 kWh Model S indicates 256.4 megawatt hours for a million miles. That's about 221 tons of TNT equivalent.

Well using the most optimistic numbers I could find the Model 3 LR does ~429km on 270 MJ battery pack. Assuming efficiency of system remains the same for 1 million miles that is approximately 1x10^12J of energy, roughly 240T of TNT or around 30,000L of Jet A-1.

Using your figure of 1e12 joules, I thought, what about a hypothetical miniaturized fast breeder nuclear reactor?

Googling, I found a document that says regular light water reactors produce power with something like 1.8 tons of fuel per gigawatt per year. And fast breeder reactors potentially could be 100 times more efficient, they say.

So if I did the arithmetic right, and if Google unit conversions didn't fail me, you could get 3.2e16 joules from 1632 kg of uranium fuel, which ends up being about 2 ounces per 1e12 joules.

So, sure, it seems doable to me. The "battery" would be about the same weight as a regular alkaline 9V. A bit smaller though.

Lol so apparently this sounded like a good enough math problem to get a lot of people interested

Ok so.. 100kwh = 350 miles ish

1,000,000 miles would need a capacity of 285mwh...

Or... 245 tons of TNT...

I don't want to be in the same zip code as that vehicle

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