Sugar-powered Fuel Cells

The Naked Scientists spoke to Professor Lynne Macaskie, University of Birmingham
04 June 2006

Interview with 

Professor Lynne Macaskie, University of Birmingham


Chris - We've heard about the science and we all know where it ends up; that's in our cars. And it ultimately translates into a lot of carbon dioxide that we think is promoting a greenhouse effect which is warming our planet up and promoting climate change. Now one way we might be able to bypass this problem is to develop cleaner sources of energy. Someone who's here to talk to us about that is Lynne Macaskie from Birmingham University. Tell us about your work.

Lynne - We were looking at alternative ways of making energy using bacteria which are very small organisms found in the soil and found in water and found in loads of places. On eof the clever things that bacteria can do is that they can make hydrogen. You can make hydrogen from the petrochemicals industry but as we've just heard, the lifetime of that industry may be finite. So it's high time we started looking at other ways of making hydrogen as a potential fuel because when it's burned, it just leaves water.

Chris - So it's a lot cleaner.

Lynne - It's a lot cleaner and the water is clean. So if we also look to a potential water crisis through global warming, we have a way of making clean water as well.

Chris - Presumably, if we take water out of the ground and turn that into carbon dioxide, Nicky, that's not carbon neutral because you're taking away a stable source of carbon that's been locked away and releasing it into the air. Whereas what Lynne is suggesting is using energy that is already available from various sources and it's not liberating new carbon dioxide. Would you say that that was a fair comment?

Nicky - That's correct, but the oil industry is looking at ways of sequestering or burying the carbon dioxide that's produced during the burning of hydrocarbons as well.

Chris - So then how does your technique actually work?

Lynne - Well bacteria can eat sugars and for this we were looking at sugars that would otherwise go to waste and may be buried and end up back in the environment. This is an awful waste of sugar and a waste of energy. Since bacteria love to eat sugars, what we decided to do was to see if we could make them make hydrogen. Now when we eat, we breathe out and the bacteria do the same thing: they eat bacteria, breathe out and they breathe out hydrogen. In Birmingham we've actually got the Cadbury plant not very far away, so we had a little project with Cadbury's to see if we could take some of the waste from confectionery and feed it to bacteria and see if we could make the bacteria make hydrogen.

Chris - How much do they chuck away that you could potentially be using? What's the energy value going down the drain each day just because there's no way to use it at the moment?

Lynne - It's very high in sugar and if it was reusable then I'm sure they'd reuse it. I don't have the figures to hand as to how much is actually thrown away. It might actually be recycled into animal feed; I don't know that information. But to be able to reuse the waste on site may have the potential to generate energy and offset some of their own fuel demands, while at the same time reduce the pressure on the National Grid.

Chris - How much energy can you generate and how do you actually do it? Talk us through the nuts and bolts of how bacteria ultimately culminate in the production of energy.

Lynne - It's a bit too premature to say how much could actually be done in the future. We can calculate that to run a house at a base level without cookers or heating, you could make a drum of perhaps one or two cubic metres of bacteria, so that's the sort of level one would be looking at. The way they do this is they make the hydrogen, and you pass the hydrogen into a machine called a fuel cell. What the fuel cell does is it splits the hydrogen and the electrons go off into the circuit and run a load, for example, an electric fan. Then at the other end, the electrons recombine with the protons from the hydrogen and the oxygen from the air to make water. So actually it's possible to couple the bacterial vats into a fuel cell and couple that into an electrical device.

Chris - How much space would this take up? Is it feasible at the moment? The beauty of what Nicky is talking about, oil, is the energy locked away in a tiny amount of oil is huge. In order to produce a viable amount of hydrogen how many barrels of bacteria would you need?

Lynne - It's a bit too soon to say that. We did a basic calculation where we calculated that you could probably run the background energy demands of a house on something that was about the size of a fridge-freezer.

Phil - How much fuel do you need to put into something like that? How much chocolate or sugar would you need to run a household or something domestic?

Lynne - You're looking at quite a lot really. You're looking at bagfuls. So it's quite unlikely that the average house would generate that much sugar. I think at the moment that we'd be looking at factories that produce very concentrated wastes and lost of it. But the next stage of the work would be to look at domestic waste and to see if in an ideal world if one could recycle one's composting material into making hydrogen, which you could then use for the fuel supply of the house.

Chris - Do you have to genetically modify the bacteria to make them more efficient at doing this, or can you find these bugs living naturally in the environment?

Lynne - You can usually find these bugs living in the environment if you go looking for them. Obviously genetic engineering will help you to make better ones but it's probably best to go with what nature has provided. Sometimes you can make bacteria breed if you put them together and you end up with better strains by selective breeding rather than genetic modification.

Chris - And very briefly Lynne, what's the time scale on the roll out on this kind of thing. At the moment this is sitting in your laboratory. When could we expect, reasonably, to see the first commercial and viable uses of this technology?

Lynne - Well the technology is likely to be installed in individual companies within five or ten years. For the hydrogen economy to take off in a real way, I think we're realistically looking at 15 years, if not 20 years.


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