Professor Tony Ryan
So far we've looked at how nature makes polymers and how we develop the ability to make our own.
Does this mean that we are better than nature?
Is there anything left for us to learn?
We look again at Sheena, a chemist extraordinaire.

When she's finished with her web, what does she do?
She eats it.
She takes all that polymer back into her body and re-processes it to make a brand new web.
Takes an old web and makes a new web.
What do we do with the materials we've finished with? [Tony stands in front of rubble filled tarpaulin.]

[Children bring in rubbish.] Well I asked you all to bring all of the rubbish you'd generated over the past twenty four hours and here it is and the last two have been brought in by, what's your name? ... Alex, who's playing the part of a bin man [Kate] and Kate who's being a bin man, please chuck your rubbish on. [Rubbish is tipped on to tarpaulin.]

Professor Tony Ryan
Whoa!
Right, well thank you very much for chucking that rubbish in. [Applause.]

So what's in here, what sort of rubbish have you guys generated?
Well you've eaten lots of these, right, some sort of snack food.
A packet and a half a day are the statistics, I don't know how much good that's doing you.
And you've also drunk lots of these, right.

So we're going to weigh all this rubbish now and find out how much there was. [Shot of tarpaulin being hoisted up.]
Up it goes - I need to run round.

And how much have we got up there?
Twenty seven kilos.
Two hundred of you have generated twenty seven kilos of rubbish.

And what happens to it?
Where does it go?
It goes in a landfill.

So you had a hundred and fifty grams each today.
Each year, each one of you generates fifty-five kilos of rubbish.
That's a fantastic amount.
It's nearly your average body weight.

In your lifetime you dispose of four tons of plastic material and it gets buried in the ground.

That's amazing!
Four tons is a double decker bus!
Just from you and it's all oil that's getting buried.

[Tony taps a plastic cola bottle.] So what can we do about recycling?
Can we turn these into new bottles?
And the answer is 'no' and I have a couple of volunteers who are ready to help me demonstrate why that's the case.

So we've already wired 'em for sound, so down you come.
And out comes the block that you're going to use to demonstrate.

[Children stand with Tony.] So what's your name? [Anna].
You're Anna, and your name? [William].
Hello William and Anna.

Right, what I want you to do is bash things.
I think - you take that one and you take that one.
[Shot of polythene stick.] Now this looks like a candle, but it's made from polythene. It's the same material as the candle. It's just a - molecules are a hundred times longer, so let's give it a bash, the polyethylene one.

OK, now, let's say that we've recycled the polyethylene many times and the molecules get shorter and shorter and shorter and now William's going to give them - give it a really good bash, William.

Oh look, keep bashing.
And what does he end up with?
A piece of string, right.
Thank you both very much indeed. ...

Professor Tony Ryan
So we can't make the same thing again, unlike our fantastic spider.
[Tony holds up cola bottle.] If we're going to recycle PET, what we have to do is we have to chop it up into little granules and make it into fibres.
It turns out that the polymer that's needed to make a bottle has to be about twice the molecular weight of a polymer that's needed to make fibres.

[Tony walks over to machine and pulls out fibre.] So we can take PET granules or chopped up PET and extrude it to make - this is a kind of a thick fibre.
I don't want to get too close, 'cos it's rather hot, right.
And we can make fibres from chopped-up soft drinks bottles.

Thank you very much for that.
So, how many of these do you think it needs to make, let's say, a PET polyester fleece?
Any ideas?

[Table with scales is wheeled in. Tony holds up jumper/balances jumper & bottles on scales.] [Four hundred]. Four hundred, OK, well let's test that.
So here we have a nice fleecy jumper and we put it in the scales and these are already too heavy, right.
So we've got about ten bottles in here and ten of them is enough to make a PET jumper.

These weigh about twenty grams each and this jumper weighs about two hundred grams.
So is a fleece the end of the line for that polymer?

[Shot of bottle of oil.] You see they're all made from oil and the oil is where they came from, so we took oil, which is small molecules, and then we built it up into a very long molecule and then we reprocessed it, we made something else, we recycled it into something else.

You see, when I was a lad we didn't call it fizzy drink, we called it 'pop' and it came in a glass bottle and you didn't get it from the supermarket, you got it from the newsagents and you paid a deposit on the bottle and when you'd finished with the bottle, you took it back to the shop and got your deposit back.

It was actually a good source of spending money.
You could go round and find these bottles and go and collect someone else's deposit.
We don't do that any more.
And the reason for that, well there are many reasons for it, but the main one is the energy required.

So it turns out that there's less energy needed to make a brand new bottle than there is needed to collect bottles, take them back to the factory, wash them with hot water, sterilise them and fill them with a new drink and bring that back to the shop again.

[Screen showing landfill process.] So all of this - oil that's been converted into various goods is now buried in landfills.
So all that rubbish that got taken away will end up underground and I suspect that when the oil runs out in a hundred and fifty years, that some of you people will be setting up businesses to mine landfills.

We're burying a very important chemical feed stock.
And is it the end of the line?
We can go from bottles to fleeces and the sad place that a polymer ends up is as one of these, a road cone. [Tony holds up road cone.]

[Sheep is led in.] So maybe the answer's in farming.
Oils, fossilised.
Maybe this is the way forward, right?
This sheep is farmed for her wool, but what we could do is we could take the gene that makes the silk from the spider.
We could splice that gene into the sheep and then get two harvests from the sheep.

One harvest of wool and the other harvest, the s.. protein from her milk - and Fritz, who you met earlier is trying to do exactly that.So that's one way we might be able to harness nature and use carbon ... carbon dioxide and sunshine to make engineering materials.

But the other way is to grow new materials.
Thank you very much for the sheep, she's been very good today. [Applause.]

We could also take something that grows in a field. In this case corn or wheat.
We can take the starch that's in the corn and wheat and ferment it, not to make bread or beer, but with special bacteria that make a compound called lactic acid and you all, you all know what lactic acid does, it's what happens when you get a stitch.

[Tony holds up plastic knives & forks.] We p... the lactic acid and then we can make an engineering material and it, it's amazing, but knives and forks like these can be made biodegradable.
That environmentally friendly organisation, known as the US Navy has developed knives and forks made from polymers that are effectively grown in fields and when you chuck them overboard into the sea, they dissolve within hours.

You see, nature's been around us for millions of years and if we're to survive and not destroy our environment, we could do a lot worse than learning from nature and learning how to harness its power.

Applause/music/credits roll