# Transcript

Interviewer
We are at Rothamsted which is an agricultural research station located just north of London and today we are going to be visiting Dr Angela Karp who is the Director of the Centre for bioenergy and climate change and she is a UK expert on the use of biofuels.
So Angela the work that your group now undertakes here at Rothamsted - can you just outline what that involves and the kind of areas that you're looking at.
Angela Karp
Yes. So what our group essentially is trying to do is to look at how we can use woody crops, non-food crops, foods that aren't used for normal agriculture products, to go into the liquid transport industry.
I
You can create biofuels from food crops and in some ways it's an easier step in terms of just fermenting the sugars to produce ethanol. But there is obviously a problem with doing that isn't there?
AK
Yeah that's right. These woody plants don't store their sugars in an easy form. They don't store them in the starch or sugar. It's locked up in the cell wall. It's a structural component.
I
And a cell wall is a very complicated material isn't it? People say just cell wall - it sounds like a brick wall - something very simple. But it's much more complicated than that.
AK
Imagine more, if you like, a fence made of wire netting except you don't have one wire, you have five or six different types of wire, all interlaced. And those wires are locked together. So some of them you can't tease apart from one another very easily because they are locked together by careful bonding.
I
And the whole idea is to give the plant strength so that it's able to remain upright.
AK
Strength and resistance. The cell wall is actually a very clever structure. But for us it's difficult because it means that we have a complex series of fibres which are all kind of interlaced and locked together. And in order to get the one fibre we want, we have to be able to unlock them and then release just those fibres out of the cell wall. Hence the sugars. And the sugars are in what's called a cellulose or hemicellulose component of the cell wall. And the other components are the lignin I talked about before. Very high calorific value.
I
That means it's got lots of energy.
AK
Lots of energy. So lignin as a polymer is higher than coal and that's the reason why you can burn these. But for us the lignin is a problem because it's the polymer which gets in the way of getting the sugars. So a lot of the research which is going on is how we can break down the cell wall in a way that releases the sugars and allows us to make the fuel.
So we are starting to screen through the willows and asking, you know, if put through a test where you try to make sugars out of willow, can we identify some which are better at doing that than others. We are also beginning to understand where does the plant put its sugars. It creates sugar by photosynthesis and can we understand how it makes the cell wall from those sugars. Can we try to select plants which make the cell wall in a way that's more easy to break down. So it's still resistant, it still keeps off water but it's easier for us to break it down.