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Poo power: Stanford engineers harness electricity from sewage

Microbial battery
The "microbial battery" developed by Stanford engineers that harnesses power from sewage. The liquid in the jar is wastewater. (Xing Xie/Stanford Engineering)


The researchers behind a novel invention announced yesterday call their discovery a "microbial battery." That's a lot more marketable than "poo power," which is essentially what we're talking about here. 

Engineers at Stanford University have discovered a new way to draw electricity from sewage. The prototype they have created is a proof of principle, but the team hopes that the discovery could eventually be used to offset the electricity used to treat wastewater, a significant expenditure in developed countries.

The microbial battery harnesses the power of unique bacteria that produce electricity as they break down biological waste. "Exoelectrogenic" bacteria slough off electrons as they convert animal and plant matter into fuel. The microbes cling to the negative electrode of the devide and the energy they produce is captured by the positive electrode, which is made of silver oxide. 

The engineers think their device can release 30 per cent of the energy that's locked up in wastewater, but lots more work has to be done. Silver, for example, is too expensive to scale up significantly, so they are looking for other materials.

The research was published in Proceedings of the National Academy of Sciences. 

Kate Allen is the Star's science and technology reporter. Find her on Twitter at @katecallen.



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How do you refill the batteries, I shudder to ask?

I'm sorry to disappoint you, but this idea was promoted by Popular Electronics about fifty years ago. They ran a feature article on it, and it wasn't new then.

From Googling, I see many stories based on this "discovery" ranting about how novel it is.

Not the Popular Electronics feature from fifty years ago, but this should make the point:
[One type of bacteria, discovered in 1987 by Derek Lovley, can generate electricity.
Here’s how you can find bacteria like these in a local pond and put them to work.][...]

And for tomorrow's special feature:

How I Discovered the Wheel

The media has become so incredibly gullible....

Sounds like a great idea. If you can get energy from something, why the heck wouldn't you take advantage of it? If the cost of implementing the solution - once it's ready for prime time - is worth it it could save governments a lot of money.

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