Has been published Tuesday, May 22, 2012 Next »

Building Plastics-to-Oil, While Polymer Recycling Remains Incomplete

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.

forum gif John Spevacek - Thursday, May 31, 2012

The comments from the speakers at the recent Plastics Recycling Conference in Atlanta (Mike, you really should have gone!) were that this technology works best as an adjunct to recycling and not as a total replacement. It can/should be used for lower quality waste - mixed streams that can't be easily separated, totally unrecyclable materials (either due to chemistry or lack of a market), or the really nasty case of when you want a good quality stream but have to take some nasty stuff along with it, in which case you pyrolyze the nasty stuff and recycle the good stuff.

In most cases, the "oil" produced still needs further refining, so it is sold to a local refinery who processes it into the various fractions. The oil produced in the pyrolysis is extremely sweet (little or no sulfur) and so you can ask for a good price for it from the refinery.

I have to admit that the talks changed my mind about the situation, as before them I felt like you. While it is impossible to say what the motivation is for all of these new PTO plants, they can be considered a good step if used as I described here.

forum jpg Mike Tolinski - Thursday, May 31, 2012

John-- thanks for the response. Yes conference, conferences -- too many to keep up with.
Anyway, I admit I'm fascinated by plastics-to-oil tech, as long as the energy consumed by the process is less than the total energy content of the fuel produced. And I understand the potential of its use for handling currently unrecyclable plastics, but...
My concern is with a perception being created that once p-t-o is up to scale, it could be seen as a potential cure-all for ALL plastics recycling -- before we've figured out all the tricks of mechanical recycling.
Already it feels like industry interest has shifted toward p-t-o development, given its relative novelty.