Pyrolysis is not a ‘future-proof’ solution in the battle against plastics, insists Zero Waste Europe. The group argues in a new report that relying on the chemical process creates a ‘leaky loop’ rather than a circular economy.
Furthermore, it argues, the process produces new, unwanted, and toxic hydrocarbons. ‘All plastics, though notably the polyolefins which are identified as ideal pyrolysis feedstocks, do not simply revert back to the precursor material from which they were formed,’ the report says.
‘Instead, they produce a wide variety of products due to aggressive chemical substances, known as free radicals, splitting from the plastic and re-combining in unwanted forms.’ These pyrosynthetic hydrocarbons lower the product oil yield and impair its quality, it adds.
ZWE believes ‘chemical recycling’ is not the answer for difficult-to-recycle plastic waste streams. Highly mixed, unwashed or difficult-to-recycle plastic waste streams, such as automotive shredder residue and computer casings, result in a pyrolysis oil with substantially increased levels of contamination.
‘The universal laws of physics and chemistry that govern pyrolysis are unlikely to change because of marketing pressure,’ the report states. ‘Decision makers would be sensible to accept that pyrolysis is not the wonderful miracle they need merely because no other back-end solution exists.’
It claims the laws of thermodynamics dictate that the most sensible solution to minimising plastic waste lies in upstream intervention. ‘This means putting investment into making plastic products less complex, less contaminated, and more recyclable,’ the report concludes.
End of waste?
Meanwhile, authorities at Member State and EU level may recognise pyrolysis as an approved recycling method. They are also discussing reclassifying plastic-derived pyrolysis oil amid talks about end-of-waste criteria for plastics.
Such a reclassification risks overlooking purification steps and underestimating the true environmental footprint, says ZWE which argues that pyrolysis does not align with objectives outlined in the EU’s ‘Green Deal’.