I’ve been reminded of a family relative we used to visit when I was young as I've read the numerous reports lately about progress in developing plastics waste-to-oil (that is, pyrolysis) methods for recovering value from waste plastics. My relative liked to do various improvement projects on his property – like building a storage shed, fences, and so on. But he never really seemed to complete any of his projects before starting a new one, which always seemed much more exciting to him I guess.
In a similar way there’s been some excitement about using pyrolysis technologies to break down waste plastics, in effect “recycling” them into usable fuel products. However, the industry's previous project – the recovery and mechanical recycling of sortable plastics – isn’t finished yet.
A recent report prepared for the American Chemistry Council shows that plastics-to-oil pyrolysis could be commercialized within the next decade (PDF of the report here). The report says pyrolysis can save energy and carbon emissions in comparison with landfilling, and can be a cheaper method than landfilling in regions where landfill costs are above a certain amount. It’s true that there’s a lot of energy contained in the molecules of “unrecyclable” waste polymers, which may explain why more news about new p-t-o plants has been popping up, even in the mainstream media.
But a root of the word pyrolysis, “-lysis,” is based on the Greek word for “taking things apart” or “destroying.” And that’s what the process does – it destroys stable, carefully synthesized polymers in the waste stream. In engineering school, we viewed all polymers as being engineered materials with lasting properties, and most waste polymers still have value for new products. Being landfilled or “taken apart” and ultimately burned seems a waste.
Meanwhile, policies, processes, and practices for optimizing polymer recycling continue to progress; ways of mechanically recovering and reusing this polymer value are still being improved. Pyrolysis could just become a more exciting distraction from this, as the project of conventional recycling lies unfinished.
Mike Tolinski is the author of Plastics and Sustainability, published in Oct. 2011 by Wiley-Scrivener, and he is Contributing Editor for Plastics Engineering magazine of the Society of Plastics Engineers in the USA. His views have been shaped by his engineering, university, and journalism experience in the plastics and manufacturing industries over the past 22 years. You can follow Mike and be alerted on blog updates via Twitter.