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A potato battery can light up a room for over a month (2013)

71 points| miles | 4 years ago |smithsonianmag.com

69 comments

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[+] jacknews|4 years ago|reply
Just use salt water?

It's even cheaper and more shelf-stable than potato, and there's quite a lot of it on the planet.

[+] foobar33333|4 years ago|reply
Or just use a solar panel. I'm sure with a battery, a single panel could light up my room perpetually.
[+] thisiswater|4 years ago|reply
Article is complete faff. The potato is not the battery, it is not an energy source, and the article says nothing about the economics of the two plates which are the actual energy source. Don't waste your time.
[+] kseistrup|4 years ago|reply
Also, does the article include in their equation the amount of energy needed to boil the potatoes for 8 minutes?
[+] nardi|4 years ago|reply
If you’d read the article, you’d know that it explains that the potato is just acting as the electrolyte, and it does mention that replacing the zinc electrode is cheap.
[+] maxerickson|4 years ago|reply
https://www.youtube.com/watch?v=36hzlFVgVa8 seems to be the video (didn't play for me at the link).

It's really a zinc and copper plate battery. Apparently boiling the potatoes can improve the power output.

[+] foobar33333|4 years ago|reply
You'd have to factor in the resource usage of producing zinc and copper plates before even considering using this as a real solution.
[+] m463|4 years ago|reply
I think this because an enormous amount of energy was use to smelt the metal from ore. Oxidizing it slowly for electricity is possibly just a weak and inefficient battery.
[+] wolfretcrap|4 years ago|reply
Is it viable? We know industrials get power at cheaper rate in some counties, is there any arbitrage possible by making huge batteries like this for residential and commercial use?
[+] dnhz|4 years ago|reply
> To be clear, the potato is not, in and of itself, an energy source. What the potato does is simply help conduct electricity by acting as what’s called a salt-bridge between the the two metals, allowing the electron current to move freely across the wire to create electricity. Numerous fruits rich in electrolytes like bananas and strawberries can also form this chemical reaction. They're basically nature’s version of battery acid.

That doesn't sound so exciting to me.

[+] young_unixer|4 years ago|reply
Isn't that a bit like saying

"The sun is not a light source, it's just very hot, which causes hydrogen to go into nuclear fusion, which releases energy in form of electromagnetic radiation"?

Or is my comparison flawed?

[+] benbenolson|4 years ago|reply
Doesn't this require the degradation of the zinc and copper plates that are required for it to work?
[+] analog31|4 years ago|reply
Yes, conversion of the metallic copper and zinc into ionic salts is where the energy comes from.
[+] ddingus|4 years ago|reply
Yes, but the plates could be cleaned and used multiple times.

For plates of reasonable size, simple abrasion would be enough.

[+] danmur|4 years ago|reply
I assume I'm just being dense, but if you have to boil the potato, surely that takes a bunch of energy? Or do you burn wood to do that in this scenario
[+] seltzered_|4 years ago|reply
Yes. The question to ask in these approaches, from an appropriate technology standpoint, is the locality around creating energy storage and what it would take to maintain the storage device, not just conversion efficiency.

For example, one may argue in a given situation one should use an induction cooktop from an efficiency standpoint (and also particulates reduction). Another may argue in a given situation one should use a woodstove if they can source the wood in a sustainable manner and can create maintain the woodstove itself locally. Not asserting a right answer here, just outlining some tradeoffs.

[+] bmurray7jhu|4 years ago|reply
Would the potato be safe to eat afterwards?

If widely deployed, I would imagine that a non-negligible number of potatoes would be eaten after being exhausted as a battery.

[+] mikewarot|4 years ago|reply
Many copper compounds are toxic, I wouldn't even think about it.
[+] ekianjo|4 years ago|reply
You dont want metal salts in your potatoes
[+] waspight|4 years ago|reply
You dont want to want to eat a cooked potato that is 40 days old either.
[+] BenjiWiebe|4 years ago|reply
The potato doesn't provide the energy; the two metals do.
[+] getlawgdon|4 years ago|reply
The implicit development is the improvement of LED efficiency.
[+] zeristor|4 years ago|reply
Might I suggest the name:

Spud-U-Light?

[+] kumarharsh|4 years ago|reply
I can't believe the level of disconnect some people on HN have with the "other" worlds.

Poor people don't need LEDs? LEDs are the cheapest light source in the long run. The electricity/batteries to run it might be expensive or impossible to get in some places.

Check out this gravity-run light source which is "essentially free" and being used in many places.

https://youtu.be/Jsc-pQIMxt8

[+] hedora|4 years ago|reply
That gizmo doesn’t exist any more.

Even if it did, the physics don’t really work. A high end bright LED light draws a few watts. Let’s say the LED uses 1 watt, and the gears are perfectly efficient. One watt-hour is 2655 foot-pounds. Assume the weight is 265 pounds with a 10:1 pulley to lift it. You’d have to pull the rope attached to the pulley 100 feet to charge the light to run for one hour, and the device would need to be 10 foot tall. Figure in mechanical losses, and a more realisitic LED, and you end up multiplying the weight, and pully ratio by ten. Now, the weight is similar to a small car, and you pull the rope 0.2 miles for a one hour charge. Make it 5 foot tall, and the weight and rope double again.

[+] aaron695|4 years ago|reply
This is wrong on so many levels it's hard to know where to begin.

Poor people don't need small LED lights and it obviously won't charge a phone. Not sure what the whole "the potato is not, in and of itself, an energy source" is rambling on about. Boiling a potato takes a lot of energy, obviously way more than a battery/potato can deliver.

Here's the rat attractant battery - https://www.researchgate.net/figure/Potato-battery-basic-com...

But jumping to the mathematics I simply don't believe it would be cheaper than a battery

I do believe a potato has a lot of energy, I'd assume much much more than a D Cell, but to turn that to usable electrical energy cheaper than a battery I'd be very surprised. I doubt this, but are unsure.

[edit] Here's someone who ran their clock for 6 months on a potato (Still not proving either way which is cheaper) - https://www.amazon.com/ask/questions/Tx3AUA83YPS7DMP/

[+] panchayoooot|4 years ago|reply
>Poor people don't need small LED lights

Huh? Reliable light is one of the best things to provide impoverished areas with, after clean water/food/medicine/sewage.

It's one of those things that we really take for granted, but if someone dropped you in the middle of the woods, I bet a headlamp and power source would be one of the first conveniences that you'd ask for.

Anyways, like others have pointed out, the energy comes from charge carriers moving between the metals stuck in the potato, not the potato itself. That particular misconception comes up surprisingly often, to the point that it's kind of a running joke in its own right. Portal 2 had a pretty tongue-in-cheek take on the gag.

[+] giardini|4 years ago|reply
aaron695 says:>Poor people don't need small LED lights... <

I commonly find myself asking for a flashlight when helping friends or acquaintances with everyday fixes. I wish I had a potato for every time they offered me their (dim, unwieldy and dysfunctional) cellphone with flashlight app.

In the old days, everyone had these widgets called "flashlights" in their homes. These flashlights worked well and had backup batteries. Today we have a bunch of morons groping in the dark with cellphones.

Fun time watching the cellphones die out during the Texas Freeze event weeks ago. "Anyone got a flashlight?" I now know the proper response is "Nope, but we've plenty of potatoes!"

[+] burnished|4 years ago|reply
Sure, in energy rich nations! But in lots of parts of the world people do not have access to much electricity for lighting.