Lately in numerous reports there’s been a flurry of chatter about alternative ways for reclaiming waste plastics. Rather than being recycled directly into new plastics, waste plastics can be converted into other energy-rich materials, such as fuel oil or other chemicals, through pyrolysis -- or directly converted into energy through incineration, already a common practice in some regions. (In my previous post, I mentioned that these issues were raised at October’s GPEC conference.)
Obviously, alternatives need to be considered for reusing waste plastic that can’t be practically transformed into clean flake and pellets for reuse. Waste-to-energy or waste-to-fuel methods are technically interesting conversion alternatives (I say “conversion,” because it feels strange to use the word “recycling” to mean the breakdown or burning of polymers into simple chemicals or gases!).
In the USA at least, discussions about waste-to-energy (WTE) projects also are complex because, unlike in smaller countries, there’s generally still a lot of landfill space available for solid waste disposal. Still, the US Congress is considering offering tax credits for WTE facilities that incinerate waste, even though certain WTE projects have had trouble staying in business on their own, and find it difficult to maintain air-quality standards.
Backers of WTE and related practices point to the incredible amount of energy contained in waste materials regularly thrown into landfills. A reported estimate says that in 2008, the chemical energy equivalent to 36.7 million tons of coal could have been “harvested” from landfilled trash in the USA alone.
The American Chemistry Council (ACC) has taken special interest in WTE-type projects as a way to handle non-recycled waste plastics, as the ACC’s Craig Cookson spoke about at GPEC. Cookson said more plastics-to-fuel projects, plus more normal recycling, would seem to reduce the social pressure that’s driving plastic bag bans and other waste-related controversies.
But can’t conventional recycling methods still be improved upon to reuse the complex polymer structures of more types of waste plastics, without destroying them? Can’t plastic products be re-designed any further to increase their recyclability? And might more widespread WTE projects tend to reduce the emphasis on using common methods to reclaim easy-to-recycle plastic packaging, such as PET and HDPE beverage containers?
For more details on WTE, see this PDF of a new report from Columbia University/the ACC.
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 by 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 21 years.