Potato-Powered Batteries Debut

MojoKid writes "Yissum Research Development Company Ltd., the technology transfer arm of the Hebrew University of Jerusalem, has just introduced what it's calling 'solid organic electric battery based upon treated potatoes.' In short, it's a potato-powered battery, and it's as real as you're hoping it is. The simple, sustainable, robust device can potentially provide an immediate inexpensive solution to electricity needs in parts of the world lacking electrical infrastructure. Researchers at the Hebrew University discovered that the enhanced salt bridge capability of treated potato tubers can generate electricity through means readily available in developing nations."

Comments

Puff piece

[ozmanjusri]

There should be a whole bunch of red faces on Slashdot for putting this on the front page.

There's nothing new about using vegetables as electrolytes, and all of the electricity is derived from the non-sustainable zinc and copper, not the boiled spud.

Re:Puff piece

[LambdaWolf]

I believe the news here is that the technology is pragmatically usable (a potato battery used outside of an elementary school classroom? That's news) and in a way that's more economical than equivalent sources. From TFA:

Cost analyses showed that the treated potato battery generates energy, which is five to 50 folds cheaper than commercially available 1.5 Volt D cells and Energizer E91 cells, respectively. The clean light powered by this green battery is also at least 6 times more economical than kerosene lamps often used in the developing world.

Lalande and Daniell Could Do It Much Better

[Black Gold Alchemist]

As far as I understand, this system is basically a zinc-air or zinc-water battery. What you get is a reaction like this:
2Zn + O2 -> 2ZnO (zinc air)
Zn + H2O -> ZnO + H2 (zinc water)

The potato is decorative, and simply acts as the electrolyte, the copper is also decorative and simply acts as substrate for the air or water reaction (it could be iron, nickel or even a graphite rod). Their are using copper, as far as I understand, because it is cheap. The copper won't be consumed. The potato won't be consumed, unless it rots. It will eventually be filled with zinc oxide, which will "clog" the electrolyte. So basically, you'll save the copper until it corrodes (likely never because the zinc protecting it from corrosion), and replace the zinc constantly. My guess is that you'll eventually have to replace the potato, but not as often as the zinc. Part of the problem with this system is that the copper is not oxidized - instead of copper wire, you need copper rust. What you really want in such a system is this:
Zn + CuO -> ZnO + Cu

That's what the Lalande cell does. It was used in the late 1880's and 90's to power stuff like telegraphs. Instead of a potato, they used an alkaline electrolyte, like potassium hydroxide. This is way, way better at conducting electricity than a potato. Before the Lalande cell, we had the Daniell cell. The Daniell cell was based on a similar construction, but it used sulphuric acid instead of potassium hydroxide. Sulfuric acid dissolves both copper and zinc oxides, which lead to problems because some of the copper sulfate would make it across to the zinc. This would lead to the corrosion of the zinc, and the copper plating of the zinc, stopping further reaction. To resolve this, a porous bot or salt bridge had to be used to stop the copper from getting the the zinc. Unfortunately, although zinc-copper is a cheap chemistry with high energy density, it is tough to recharge successfully. This is because when the reaction is reversed, and zinc oxide is changed to metallic zinc, the zinc plate will change shape. This will cause the shorting of the battery, and its destruction. Zinc-copper is not really used all that much these days. Zinc manganese appears to have replaced it because it is cheap and has higher energy. It still has the same recharging problems, and if we could solve em', lithium would be out of business.