Microbial Fuel Cells

Based on a Biopact report:

Microbial fuel cells (MFC) took a step closer to commercial reality recently when MIT students showed off a MFC that efficiently converts cellulosic biomass into electricity and biological engineers at Oregon State University reported that they have designed an MFC that is capable of generating about 10 times more electricity than previously possible from an air cathode microbial fuel cell of the same size.

These and other breakthroughs have taken microbial fuel cells out of their experimental status and closer to beeing ready to be used in real world applications.

A MFC converts chemical energy, available in an organic substrate, directly into electricity. To achieve this, bacteria are used as a catalyst to convert substrate into electrons. In principle they can be fed virtually any type of biomass, from rotten fruit and cellulose to algae and mosquitos.

(above) Schematic of a MFC - Microbes in the anode compartment metabolize organic fuel (in this case glucose) and release electrons, ions and C02. In the cathode compartment electrons combine with ions and oxygen to form water and close the circuit. Credit: IntAct Labs

In theory, biological power systems offer a number of advantages. Biological systems may offer a high power-to-weight ratio, convenient fuel storage and many of them make useful byproducts like molecular oxygen. Basic advantages are that a catalyst, which is normally expensive and easily fouled, is not needed and the fuel doesn't have to be clean, It can actually be dirt, or waste products.

Comments

[garsky]

So THAT'S why Doc Brown was using garbage to fuel the DeLorean...

[bigTom]

I've been hearing about these things, but knowing that fouled up electrodes can ruin fuel cells, I'd assumed they were impractical. Do we have any readers who know enough to comment on the prospects?

[BillO]

I see that the new process can generate 1 to 1.5 kw per cubic meter of material. Quite a long ways from powering a car...

[bigTom]

I think a few wastewater treatment plants may be using something like this to become self sufficient in power. Perhaps this sort of thing could be used for stationary power generation in rural areas? I suspect you can't quickly turn it on/off, i.e. it is probably not very dispatchable.

[JohnBo]

Hi bigTom, I don't think one would be concerned in turning it on and off. It's a cell like a battery. When you connect a load to the cell the reaction supplies the current. When you disconnect the load the cell reaction stops.

[greg]

Would be great to feed it with your garbage disposal instead of filling up landfills. What comes out after the fuel is used?

[bigTom]

JohnBo; I doubt the micro-organisms quit metabolizing when you stop drawing current. Presumably the potential energy liberated during such a period is wasted. Unless it is being stored in chemical form.

[Alt Fuel Fan]

Recent efforts into Hydrogen Fuel research have uncovered an improved method for creating hydrogen gas - the process utilizes microbial fuel cells to produce carbon-neutral hydrogen with *nearly 300% more energy than current procedures.

[skid steer loaders]

This stuff amazes me. I can't believe this isn't talked about more.

[Made in China]

Made in China

[ecomfort]

They should build more of this and promote it.

[Cebu Pacific Promo]

Nice one.

[Chicago General contractor]

I am beginning to understand that biological power systems offer a number of advantages. Biological systems may offer a high power-to-weight ratio