Science Interviews

Interview

Sun, 26th Jul 2009

Life Cycle of Rubbish

John Williams, Polymers and Materials Manager, National Non-Food Crops Centre

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Chris -  Now one way to deal with rubbish is to use the right materials in the first place. In other words, things that we can reuse or recycle much more easily. And Dr John Williams is the Polymers and Materials Manager at the National Non-Food Crops Centre where he works on understanding the whole life cycle including things like recycling and then the disposal of materials when they’re no good anymore. He’s with us now. Hello, John.

John -   Hello Chris.

Rubbish binChris -   Welcome to The Naked Scientists.  So first of all, define the problem for us if you would.  I mean, basically, I think what you’re saying is that we are using materials which we are doing without any thought for where they’re going to end up in the long run and we ought to perhaps work backwards and think of things that we could use, which we could do something sensible with again.

John -   Well I think, yeah, it’s absolutely. The key thing here is, where do we get the carbon from?  And we’ve been very dependent over the last 70 or 80 years on fossil carbon.  Practically everything we touch or make or energy fuel material-wise comes from fossil carbon and we’ve been easily sort of disposing of that fairly lazily without any thought process.  And I think - recently now we’ve started to put climate change and so forth in and then also recycling talks and so we just sometimes have to maybe take a little bit of a step back and say whilst there are obviously valuable materials within our waste feed stocks, which we can take out like simple metals and so forth that we can use without any problem.  Some of the others perhaps we have to be a little bit cleverer with. For example, if you take say PET in bottles we can recycle that and closely recycle that back to itself several times before we then have other options as to how we have to deal with it.

Chris -   But the problem surely is that you’ve got to make sure that it’s just bottles going into the mix so that's in itself a difficult task to do because people will throw lots of things in because they don’t know what PET is versus other kinds of bottle material.

John -   Exactly.  I mean, there’s been a lot of work on trying to identify sort of waste streams and try to sort of transmit that to the public at large, and sort of do it.  And it is very difficult one sometimes. Sometimes you have to actually take a bit of a leap forward and, say, well actually we’re going to have to deal with that on a much more centralised fashion and segregate that downstream.  But you’re still going to end up with a massive material which either cannot be recycled that easily, or is energy efficient to do so or environmentally beneficial to do so.

Chris -   So should we just stop using those materials and do what I saw when I was at Cambridge University’s 800th anniversary Garden Party last weekend, very nice.  It didn’t rain which was amazing.  And I had a plastic or what I thought was a plastic cup but it printed on the side of the cup was the words, “This is biodegradable”.  It may look like plastic but it’s not.

John -   Well exactly.  That’s certainly one option.  And if we look at sort of non-fossil materials, we use bio-based renewable materials.  We can develop not only the plastics and materials that we’re currently so used to, anyway, and in fact, they’re exactly the same.  Bio-based polyethylene is exactly the same as oil-based polyethylene.  But we can actually also develop some perhaps slightly cleverer materials like polylactic acid, for example. That’s probably the one you saw.  What we then have when it comes to a downstream option, we can compost it or we can take it through, for example, anaerobic digestion and start generating renewable energy.  So it’s all about resource efficiency and the best use for carbon here. That’s what we really have to start looking at and concentrate on.

recycleChris -   I met a lady when I was in Australia a few years back, called Veena Sahajwalla.  And she won a prize because she pointed out that people making iron, for example, from its ores have to add huge amounts of carbon in order to reduce the iron from iron oxide down to iron and make carbon dioxide in the process.  And she said: “Why are we throwing all this plastic into landfill when we could throw plastic into a blast furnace?” Because to be honest, those kind of temperatures, it doesn’t care whether it’s charcoal, coal, or other sources of carbon to get the carbon into the furnace.  So is this something we could consider here in this country where we could say, “Right.  What other processes need just the source of carbon and it doesn’t actually matter what we start with?”

John -   Well, I think that’s right.  The only thing you have to be slightly careful of is the source the carbon because, obviously, if it comes from a fossil-derived carbon and you're venting say, CO2 to the atmosphere for example, then you are obviously exacerbating the climate change scenario that we’re trying to actually avoid.

Chris -   But the point is, that stuff’s going to go into the atmosphere anyway, if it gets burned and doesn’t turn into anything useful, or it’s going to go in a landfill and rot down of a millions and millions of thousands of years probably, or going to the sea and turn into particles which will cause a problem there.  So it’s the lesser of all evils, isn’t it?

John -   To a point, yeah.  I think you just have to look at time scales and emission targets and so on.  It’s so - I mean this is what the difference these days.  I think it's that we’ve been so used to the linear situation of free stock all the way through to the finished product, whatever that may be, to disposal without really sort of connecting to the disposal and back to say, the free-stock end.  And now that’s what we’ve really going to start doing.  So we've got to start doing that, anyway.  But on top of that, we’ve also got to start looking at the fact that we’re also trying to mitigate greenhouse gases at the same time.

Chris -   Could we just look at the mechanics of how you would see something like this working?  So, if we take the average family who goes to the supermarket, they buy a fridge-load of shopping. There will be multiple different containers made in multiple different materials. How do you see them actually being able to do their bit so that we can turn lots of that stuff back into useful things that go back on the supermarket shelves, or basically don’t end up in landfills or going up as greenhouse gases?

John -   Well, I think we’ve seen a lot of work in recent years where, you know, all be it – there is still a huge amount of confusion out there in terms of what bin you put what into.  But the middle ground, if you like, for what the waste guys and now looking out in terms of processing, I think it’s going to be much cleverer than it was. I mean, it’s no longer the case of, sort of trying to pick these things up manually.  You know, this near infrared, this laser technology, this flotation technology, that pulls these – many of these materials out into usable and recognisable chains. You then have an option to something with them.  The other work that, for instance, we’re involved in is, for instance, if you look at food waste which is a huge problem. It’s alright saying we will divert food waste away from the landfill to say, anaerobic digestion.  But a lot of that food is actually wrapped in something and you’re not seriously asking the public to sort of unwrap every piece of food stock they actually get their hands on and trying to dispose of that from a home-based situation.  So, you know, if you say take a different view on that and say we’ll use a slightly different plastic or a very different plastic, which will actually be compatible with a disposal route, you then start to get this whole circle thinking that we’re actually trying to achieve.

Chris -   But, John, this doesn’t sound like rocket science so I don’t mean that in a discouraging way to you.  It sounds pretty simple, pretty logical thinking.  So, why is not happening?

John -   Well, it is.  It is happening in many cases.  I mean, we’re involved in many projects and the government is pushing this heavily.  But, of course, what you’ve got is you got crashing bits of legislation.  You’ve got a little bit inertia in the system as well.  You know, we still have high landfill targets in this country which we’re obviously trying to bring down rapidly.  It does take time to move these things along, you know.  It is a complicated system and that’s why sometimes I think you have to recognise that not everything can be recycled or is sensible to be recycled and that’s really the waste rumour we probably need to try and get away from other things which are a little bit more obvious, shall we say, and start looking at things like gasification and pyrolysis or something like that.

Chris -   Which we’re actually going to look at shortly later on in the programme, how we turn some of this rubbish into gases that we can then burn and therefore extract a sort of second bit of energy from them before they end up as a green house gas.  But this sort of brings us back to where we started, which is that, how do we actually end up changing policies?  So we say, instead of using material X to put your yoghurt in or to put your milk in, we need to use material Y because we know that we can do something better with that.  How far away from actually influencing policy are we on this from?

John -   I think we’re a lot closer than we were.  If you look at where we were a few a years ago, there’s really, you know - the connection’s particularly the material chain.  We’re really a million miles away and part of the reason for that was because everybody was concentrating to a large extent on fuel and energy.  When you actually then start to look at the material chain and say, well actually nearly all of that comes from fossil materials and disparity massive huge amount of material choices that are in there that perhaps don’t need to be in there.  That we can, perhaps, look at the chain a little bit better and familiarize it better and actually, really go back to the market and say, you know, there’s an incentive to take a material down a particular route and there’s a disincentive if you take the wrong material down the route.  So, it takes some time but it is starting to happen.

Chris -   So maybe one day, you know, never know and well, someone might pay for me for what I throw away.  Thank you very much.  That was Dr John Williams.  He’s from the National Non-Food Crops Centre.

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