A new research report from an international consulting firm said that unless the yield from recycling plastic PET bottles is 50 percent or greater, disposing of the bottles in a landfill will lead to a lower carbon footprint.
Recycling is definitely not always the lowest environmental footprint, said Eric Johnson, the Zurich-based research analyst of SRI Consulting and author of the report, PET's Carbon Footprint: To Recycle or Not to Recycle.
You need to look at what happens to all the plastics collected, he said.
For recycling to make sense from a carbon-footprint standpoint for every 100 tons you collect, you need 50 tons to come back and go into resin for products, Johnson said in a phone interview Aug. 10. If you can't do that, you need to think whether you should be doing it because if you do it badly, it doesn't make sense from an economic and environmental standpoint.
For countries with adequate space and with little recycling infrastructure, disposing of bottles in a landfill generates a lower carbon footprint than recycling or incineration, he said.
Officials from the Washington-based Association of Postconsumer Plastic Recyclers and the National Association for PET Container Resources in Sonoma, Calif., disagreed with the conclusion that it makes more sense to landfill PET containers especially considering the need to conserve raw materials. Both groups declined further comment without first seeing the full report, which was published Aug. 9.
The report analyzed the carbon footprint of PET bottles from production of raw materials to disposal, and secondary packaging from cradle to grave.
Johnson said that take-back programs and PET bottles collected through deposit programs generate yields large enough that those recycling efforts produce a lower carbon footprint than landfilling, but that curbside programs do not.
The problem with curbside collection for plastics is that you end up with a high amount of contamination from both mixed plastics, as well as dirt and crud, and that tends to downgrade the quality of the recyclate, he said. Maybe as much as one-third of the material collected goes to low-grade applications or is lost during the cleaning process.
Based on its evaluation of the best curbside collection programs in Europe, SRIC calculated the yield from the collection of 100 tons of recycled PET is roughly 45 tons meaning disposal of the bottles would create a lower environmental footprint.
The key to this is not in raising [curbside] collection rates, but in improving yields, especially in sorting and to a lesser extent in reprocessing, said Johnson.
Yields are not a problem when bottles are collected through take-back or deposit programs, he said. Precise figures are a bit vague, but the yield is probably around 70 percent, he said.
However, take-back and deposit systems cost more than curbside, and they cover less material, Johnson said. So in a nutshell what we're saying is that the design of the recycling system is critical. If you're going to recycle plastics, you're better to cherry-pick some fractions such as PET bottles, do them properly probably not through curbside and ignore the rest. If you can't do it right, you're probably better off to landfill, if you have space.
Johnson said he understands that recycling has become more important globally as people try to conserve natural resources. But whether that should be the driving reason to recycle depends on how scarce you think those resources are.
All petrochemicals as a percent of oil are less than 5 percent, said Johnson. I realize that you have to start somewhere, but there are a lot more obvious places to cut energy use than to recycle PET bottles.
Other findings of the report include:
* PET recyclate has a lower footprint than virgin PET, and makers of products such as straps, films and fibers from recycled PET should be able to claim that they are lower-carbon alternatives than similar products made from new PET.
* The distance baled PET bottles are shipped does not significantly affect the carbon footprint even when they are shipped to China.
* Incineration creates the highest carbon footprint because burning bottles in waste incinerators sends greenhouse-gas carbon dioxide directly into the atmosphere. This footprint can be reduced somewhat by generating power and heat from the incinerator, but the net effect is still carbon-positive, said Johnson. Most incinerators are not efficient power generators because they are designed to get rid of waste.
SRIC is based in Menlo Park, Calif., and is a division of Access International LLC.