Making the right choice. No, really!!
16 December 2007 by David Bott
I had a really interesting meeting at the Department for Environment, Food and Rural Affairs (DEFRA) yesterday. This was a result of a combination of meetings over the last year when they have engaged with us on the concept of the Materials Property Validation Centre. It culminated in a discussion after the last Board Meeting and an invite to go and discuss our ideas. I have written about the MPVC before. It is a complex problem and one that requires a lot of thought before action. Our choice of materials increasingly takes account of many parameters, but rarely that of total environmental impact. The route taken to get to the “pure raw material” is often not clear and therefore determination of the imbedded energy or imbedded carbon is not unambiguous. To take account of the equivalent “onward” numbers is even more fraught.
For example, I spent 4 years working for ICI Acrylics where we spent a lot of time trying to determine the most appropriate applications for poly(methyl methacrylate) (PMMA) and then persuade those who supplied such applications that the logical materials choice was Perspex or Lucite. It was never clear-cut and the competition with polycarbonate was long and hard. One advantage PMMA did have was that, if you heated to up to about 300oC, it would smoothly depolymerise to monomer and allow full value recycling. We did the energy balance calculation and showed that the cost of this process was significantly less that producing new monomer by the Crawford process we used at the time – a reaction between hydrogen cyanide, acetone in the presence of concentrated sulphuric acid. I think we even tried to supply cutlery to the Sydney Olympics based on this idea – although we failed to take account of the required physical properties of materials to make knives and forks in the process!! (It was strain to failure that killed the idea) The problem was that more investigation showed that other manufacturers had lower environmental burdens from their routes – but that the new route we were then seeking to implement was better again. Since methyl methacrylate molecules don’t come “tagged”, it was difficult to work out what the environmental cost of any molecule actually was – it depended on its provenance!! This led, rather interestingly to a suggestion that we changed our business model and “rented” methyl methacrylate to our customers and managed the whole cradle to grave cycle – not of the materials, but of the base chemical!! About this time, ICI decided to sell the Acrylics business and I lost touch with their thinking.
Similar debates are played out often – I know from conversations with Wyn that aluminium has a similar situation – it costs to produce the “virgin” metal but once, produced, it can recycled often with very little deterioration in properties. I am sure steel and other metals get close to this, but polymers (notwithstanding the story above), ceramics and composite materials all have real problems realising the re-use or recycling to full value without the consumption of significant energy. Much is made of materials recycling these days, but there is still too little work to work out the real balance between the energy and/or carbon load of this full value recycling and finding other ways to re-use the basic material – as fillers, extenders or fuels.
What we have agreed with DEFRA is that we will organise a meeting (or possibly series of geographically moving meetings) that bring together all those with a stake in the area. Watch out for more details after the Christmas break.