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Could we run an electric car on a tank full of electric eels?

I've heard electric eels are around 400 to 500 volts and can keep shocking for up to an hour. They also have a 10 volt system to sense with, which might be good for the headlights and cd player.

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No but it'll work for a hovercraft! (if you don't get the joke you're clearly not a fan of Graham Chapman or Eric Idle) – Carl Witthoft Jan 8 '14 at 16:30
I wish I could give this question +10^6. – joshphysics Jan 8 '14 at 16:34
They have grown artificial meat in the lab so why not artificial eel muscle? – Jitter Jan 8 '14 at 16:54
Jitter, they've built batteries in the lab, too. Guess which is easier to do :-) – Carl Witthoft Jan 8 '14 at 18:03

2 Answers 2

Well, believe it or not, eels have been used to power Christmas trees (youtube link), so powering an electric motor isn't quite out of the question. However, Eels emit that 400 V at 1 A = 400 Watts (though the youtube video says that the eel was emitting 800 Watts). An electric car requires over ten thousand Watts of power to operate.

So in theory, you probably could do it, but the power would be intermittent at best and you would need a fair amount of eels. Plus feeding them might get more costly than the electricity you'd save.

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Could they charge the batteries overnight? – Jitter Jan 8 '14 at 16:24
If it discharges regularly for the duration (i.e., does not sleep), it might be able to do so. – Kyle Kanos Jan 8 '14 at 16:35
@KyleKanos is that a Nocturnal Emission joke? – Carl Witthoft Jan 8 '14 at 18:04
@CarlWitthoft: No it was not. Nor would I ever make a joke about that either. – Kyle Kanos Jan 8 '14 at 18:10

The way every electric car works is by converting electrical energy into kinetic energy. The externally released energy of a discharge of Electrophorus electricus has been studied and has been found to be around $17 \mu\mathrm J$ per discharge. Since kinetic energy is $E_k = \frac{1}{2}mv^2$, if we assume a combined driver+vehicle weight of 1000 kg, then that would give $v \approx 0.6$ m/hour given a wholly unrealistic 100% conversion efficiency. These same researchers let the animal recover for around 3 minutes after each discharge and were able to get thousands of discharges. So we can calculate that one could get 20 discharges every eel every hour. (Multiple eels in case one were interested in going at higher speeds, e.g. as might be required for racing slugs or tree sloths.)

Bottom line: if you're really not in a hurry, then yes, you could power an electric car with electric eels.

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+1 Interesting. I couldn't find $17\muJ$ directly in the paper - they cite energy per gram. Whereabouts did you find / calculate the number: the reason I ask is that taser pulses are about three orders of magnitude higher and defibrillators about three orders again (although here one is specifically aiming for currents through the heart deep in the body). An electric eel can stun a full grown human, so the value sounds a little low. – WetSavannaAnimal aka Rod Vance Jan 9 '14 at 22:25
Good question. It seemed low to me, too, so I'd appreciate a cross-check on the calculations! Toward the bottom of the third page of the study I cited (page 223) it says "In the previous observations, only part of the electric energy was actually determined which is released externally. [...] Subsequent recordings and several improvements in technique have shown that this figure [is] $4 x 10^{-6}$ gm. calorie." A gram calorie is defined as 4.184 Joule, so that's how I got $17\mu \mathrm J$. – Edward Jan 10 '14 at 0:34

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