Electricity from thin flexible strips
While flat solar cells using photo voltaic technology have application on roofs or in open fields as in solar farms, there are other situations were a different kind of technology could be useful. Jenny Nelson demonstrates a photovoltaic module. It is a thin flexible semiconductor which generates electric current when it absorbs light. It could be used on curved surfaces, even inside buildings on blinds and curtains. As Jenny Nelson explains, technologies such as this reap large dividends when developing countries use them to replace energy production from the burning of kerosene. Jenny Nelson sees a future of local distributed energy production rather than large power stations and the losses that come with power distribution.
Robyn Williams: Now we meet Jenny Nelson, professor of physics at Imperial College in London. She visits Australia a lot, and indeed works with our own Professor Andrew Holmes from the University of Melbourne, and she's showing strips of plastic that generate power from the sun.
Jenny Nelson: Well, they are bits of plastic, in fact they're almost entirely plastic materials, but it's a photovoltaic module which is going to generate electricity when it's illuminated with light, particularly with sunlight, and what's special about it is that, well, you can see it is flexible, and it's flexible because it is made from a very thin layer inside of a coloured plastic semiconductor which is able to generate an electric current when it absorbs light.
Robyn Williams: And what about the other one with much thinner strips?
Jenny Nelson: This is the same idea, it's just arranged in a different design, but this is different because it's a device, and as you see it has a switch and here it has a little LED. So this is a solar torch, if you like, it's a kind of an example of the sort of thing that you could make with this type of technology. So these solar torches could be manufactured on a large scale really relatively cheaply for a couple of…
Robyn Williams: Yes, a tiny bright light, an LED.
Jenny Nelson: It's a tiny bright light, but if it's very dark that will be bright enough to read by.
Robyn Williams: Oh sure, I remember a friend of mine, Jeremy Leggett from Solarcentury had a scheme using something like that in Third World countries, in the villages, so that instead of having some nasty kerosene lamp which is giving everybody cancer and absolutely filthy, you could have something like that in every village. It only costs about six bucks to make, quite cheap.
Jenny Nelson: Yes, these could be cheaper than that. That's actually quite interesting, what you just said about the development work, because at the moment my PhD student, Chris Emmett, he's in Rwanda and what he is doing in Rwanda is setting up, along with other students from Imperial, a sort of a pilot solar home system where they are installing solar PV technology in a small community, and then the means by which they can monitor that and work out what the demand is, what the production is and how the balance works out.
And we're not just concerned about how much it costs, we're also concerned about what the energy budget is. So if in the end of the day one of the things we want to do using solar technology is to substantially and quickly reduce the carbon emissions, then it's very important to look at developing countries, because developing countries are in a situation where they have to choose. And you mentioned kerosene, that's often the option that's used for lighting in off-grid situations, and when we did the calculations of the energy budget of solar technology in a village situation, one of the things we looked at is lighting, and if we look at solar cells replacing electricity from the grid, the advantage in terms of carbon emissions was not that large. But when solar cells replace kerosene lamps and you take into account transport of the fuel and all of the associated energy costs, the advantage is very high.
Robyn Williams: And of course there was a paper I think in either Science or Nature last year that showed that kerosene kills two million people a year, two million. The costs in terms of human lives and misery is just absolutely huge, isn't it.
Jenny Nelson: That's right. So solar can also bring an improvement in quality of life apart from the big improvement in quality of the future.
Robyn Williams: As another aside of course the SolarAid, the patron at one stage was Cate Blanchett, but it then switched to Ian McEwan. But the material you've got on your lap there, those plastics, quite different from the photovoltaics based on silicon. Do you work on those as well?
Jenny Nelson: I would never say that we want to replace silicon panels with another technology like this. This, as you can see, is a flexible layer and you could have a situation where this material is applied on top of a curved surface. You could use it, for example, in things like these blinds or in textiles, and then be able to capture the sunlight in a situation where you simply couldn't use silicon because silicon will require a sort of stiff, heavy [material] and it would be opaque.
These materials can be made in different colours. Ideally...architects always like a blue and green, they don't like orange very much, but now we're getting to the point where blue is possible. And of course there are also materials which are absorbing only in the infrared, then you get something which effectively looks transparent but it's still generating light. So the point is, compared to silicon this technology could be applied in situations where silicon can't, and therefore it expands the range of options where you can introduce solar PV.
Robyn Williams: Yes, we had Andrew Holmes on The Science Show a few weeks back after his being given the Royal Society medal as a result of doing this sort of research on those polymers, and he was talking about printable solar materials. And I think you work with him, he comes to Imperial as well, doesn't he.
Jenny Nelson: Yes, we work in the same field, I've collaborated with him in the past, and in fact this is printed. This was deposited using a printing machine through a slot dye technique. There are a number of different options, but the point is that the starting material in here is a solution and you find a way of putting it down. It might be contact printed, it might be ink jet printed or something like that, it could be gravure printed very fast.
Robyn Williams: Very fast indeed. But if you look at solar, you've got solar thermal where you actually heat water or heat something, you've got the two you describe, the photovoltaic and the polymers, if you look at this sort of turning point in history where coal and the fossil fuels are beginning to get even more iffy than ever before and you're looking at solar being transformed at a tremendous rate, becoming cheaper and cheaper, how do your calculations show it turning out?
Jenny Nelson: There is no doubt that solar is already competitive. In developed countries like the UK in Europe we are usually comparing with the cost of grid power, and solar is already competitive with the cost of grid power in southern Europe, in Italy, for example, in parts of Spain, for example. In a couple of years it will become competitive more in northern Europe, and this is driven really by two things; one that we can predict moderately well which is the continuing reduction in the cost of the solar, this is going to be important, and then the other factor we don't know that well and that is what's going to happen to the price of grid electricity as fossil fuels become harder to obtain and therefore more expensive.
So in September last year the European Photovoltaic Industry Association has published the relative cost and the point at which we expect PV to reach what we call grid parity, so that means costing the same as grid power, and basically within a couple of years we're there, in Europe. In Australia, as you probably know, you're already there and have been there I think for a year or two, and what you need to do is to convince people it's worthwhile doing it.
Robyn Williams: Well, it's very interesting, because if you consider the amount of energy that goes up in a coal-fired power station, 70%, as you burn the coal, goes up into the sky. So you're down to 30% efficiency if you're lucky before you even start, and then the grid is four times less efficient than it need be because you've got wastage all over the place. So it looks increasingly 19th century, doesn't it.
Jenny Nelson: I agree. I think also at the heart of the power station paradigm, it's a model based on centralised electricity, the idea that that electricity is a commodity that you can buy when you need it and ignore it when you don't need it. And a more appropriate and efficient way of managing our energy needs would be to think about what you need it for, where you need it, generate in a distributed sense, and basically to manage the energy use in a more intelligent way. It's not just something that you turn on the tap and there it comes out, it is something that you should think about and plan. I think until now the big problem is energy has been too cheap, electricity has been too cheap, and so the whole infrastructure and state of mind hasn't been developed to think about and use it smartly.
Robyn Williams: So if you look to the future, ten years time, what will it look like?
Jenny Nelson: I'd like to think that the world could change a lot in that time. It has actually been quite astonishing, the way in which solar technology has developed, even over the last five years. I can see a couple of things. One is that I think users and both individuals and corporate users will be forced through cost and through regulation to think about energy needs, managing demand and supply in a more clever way, and I think that's something that people will be thinking about much more.
You know, the young people who are coming up now through school and college are very aware of the issues, and that's going to influence behaviour in the future. So I think we'll see changes in behaviour. We'll certainly see changes in the technologies that are used. I can see solar continuing to grow but also other renewables. And I can see a more distributed generation system being implemented with much more local generation. That's something that we're going to have to do if we're going to overcome the problems that we have.
Robyn Williams: The options for energy changing fast. Jenny Nelson was last here in September. She's professor of physics at Imperial College in London.
- Jenny Nelson
- Professor of Physics
Imperial College London
- Robyn Williams
- David Fisher