Moss-powered radio

Chris - We're always hearing about green energy, but how about a way to make electricity from plants rather than the metals and chemicals? That's the approach of Paolo Bombelli and Chris Howe. They're from the Biochemistry Department at the University of Cambridge...

Chris - So Chris, why on Earth, but why have you done this?

Chris H. - Well, because it seem like an interesting challenge really where my lab were interested in studying photosynthesis and you can think of photosynthesis as using tiny little electric circuits inside plants and algal cells which are powered by the sun. And so, you ought to be able to tap into that and get a small amount of electricity out. So, it's like a kind of photovoltaic cell, but using plants or algae instead of silicon.

Chris - Paolo, how does it work?

Paolo - Well, okay first of all, believe it or not, we got this little garden in the studio and if anyone want to see it, I would suggest to going in youtube and look for Moss FM. In that respect, I need to acknowledge that the person who actually created this is a designer called Fabian Felter. So moving back to the difficult question, how it works, thanks to Fiona, we got an idea how a battery is made. Actually, in some very similar way, this system operates in a sense that we got an anode made by carbon and a cathode made by carbon again, but with nanoparticle of platinum that acts as a catalyst. The photosynthetic organism is mostly harnessing the energy of the light and using it for something that is called water photolysis. So, that means it's breaking water to form oxygen and we all enjoy the oxygen generated by moss and other plants and also, protons and electrons. Electrons can travel around an external circuit and protons that are positive charges travel through the internal path from the anode to the cathode and be recombined on the surface of the cathode that's the catalyst.

Chris - So, just looking at this, we've got lots of little pots of moss growing, all with crocodile clips attached to things coming out of the pots. That presumably is attached to the electrodes on which the moss is growing. So, that's collecting the current from each of the moss cells if you like, the batteries and directing it - how do you store or collect the energy, Chris?

Chris H. - So, we can do different things. We can use it directly and so, we can for example use it to power little digital clock if we want to or an environment sensor.

Chris - What's the voltage of a moss? How much potential difference does it produce?

Paolo - Between 400 to 500 millivolts and this dependent of the radius potential of the system that donate electrons on the anodic side and the potential of the cathodic side, something that has been discussed through this programme.

Chris - 400 millivolts, that's pretty good. That's half a volt.

Paolo - As a matter of fact, this small garden is made by 10 pots and overall, we got around 4 volts because they are all connected in a series.

Chris H. - But it doesn't mean you're not going to get electrocuted when you're out in the garden spiking the lawns.

Chris - Very reassuring.

Chris H. - Don't worry.

Chris - Can we have a go with it?

Paolo - Yeah, definitely. I think we can try to power a radio.

Chris - It would be fun if we can tune in to our own programme.

Paolo - Okay, I think everything is connected.

Chris - Well, that's an improvement on this programme. It sounds much better.

Chris H. - I think we've doubled the listening figures.

Chris - Well, it's certainly working. There's a little red light on and there is some static coming out from the speaker but I don't think the content is quite up to scratch.

Paolo - Definitely, no. can I suggest perhaps...

Chris - We just turn it down very slightly so we can hear what you're going to say. Normally, you would be picking up a radio or something.

Paolo - Yes, we do.

Chris - So, we'll put it down to there being some kind of shielding in this building. There's a lot of metal around here, so it could be blocking the signals. But that's actually working. That's producing quite a lot of noise.

Paolo - Yeah, at least it's noise.

Chris - Chris, could we use this sort of - this is a demonstration, but could we use this more broadly to actually do useful things and power useful gadgets in the environment using this technology?

Chris H. - I think in the right kind of setting then you might be able to exploit this. So particularly, we're interested in situations where there isn't a good power supply so you might be thinking of rural areas where in Africa maybe or possibly refugee camps. Lots of possibilities where just a small amount of power can make a big difference.

Chris - Just moss or will any plant do this?

Chris H. - Lots of plants will do it. This is just moss off the bike shed roof in the biochemistry department and nothing fancy about it.

Chris - Thank you very much, Paolo Bombelli and Chris Howe from the Biochemistry Department of Cambridge University. Is that the world's first moss-powered radio? Probably is, isn't it?

Chris H. - I think it probably is, but somebody out there will probably correct us.

Chris - If you're no different, let us know.