Reverse chemistry making inroads in fuel production

This new fuel processing technology paper, published by Elsevier B.V., details the scientific protocols of the "pyrolysis of HDPE waste grocery bags followed by distillation" that resulted in a "liquid hydrocarbon mixture with average structure consisting of saturated aliphatic paraffinic hydrogens (96.8%), aliphatic olefinic hydrogens (2.6%) and aromatic hydrogens (0.6%) that corresponded to the boiling range of conventional petroleum diesel fuel."

The bottom line, according to the abstract, is that "liquid hydrocarbons with appropriate boiling range produced from pyrolysis of waste plastic appear suitable as blend components for conventional petroleum diesel fuel." It makes sense: if you can make plastic from the same raw material as you make fuel, then why can't you reverse that and make fuel from the plastic?

Sharma, of the Illinois Sustainable Technology Center, Prairie Research Institute, Univ. of Illinois, Urbana-Champaign, along with the other members of the team from the U.S. Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, in Peoria, IL, believe they have developed a way to rid the world of those ubiquitous HDPE plastic grocery bags.

The big problem with the bags is that only a small percentage of them are recycled (13% of the approximately one trillion produced in 2009 were recycled in the U.S., said the report citing EPA figures). The authors also note that plastic bags "contribute to the so-called Great Pacific Garbage Patch of floating refuse in the Pacific Ocean and have been detected as far north and south as the poles."

Recycling of HDPE grocery and retail bags has been a fly in the ointment of the plastics industry for many years. While many retail outlets, especially grocery stores, have successfully implemented recycling programs, there are still a lot of plastic bags floating around out there (pardon the pun).

Companies that depend on the recycling of these HDPE for the products they make include Trex Inc., which has made its increasingly popular Trex decking and railing systems using recycled HDPE (typically post-industrial) combined with recycled wood. Trex started recycling bags and film in grocery stores in 2008, which has had a good measure of success.

While there's a lot of ambiguity surrounding just how many HDPE film bags are recycled in a given year, a report produced for the American Chemistry Council released in 2013 using 2011 figures, estimates approximately 1 billion tons of post-consumer bags and film was collected for recycling in the U.S. Another report published in 2008 from the Food Marketing Institute noted that the price of HDPE bags and film averaged $400/ton at that time.

Hilex Poly Co. has successfully recycled HDPE retail bags, and won awards in 2012 from the Flexible Packaging Association and in 2013 from the SPE for its Bag-2-Bag program that recycles post-consumer bags into new bags.

So we know that there are a number of success stories surrounding HDPE bag recycling. However, with recycling rates apparently so low, the big question is can enough bags be collected (in the post-consumer waste stream) to create this diesel fuel in meaningful quantities that Sharma et al have proven to be viable?

A company in Niagara Falls, NY, is already doing this. In November 2013, JBI Inc. about which PlasticsToday has previously written about, released its latest report, announcing record quarterly fuel production levels for Q3 of 170,725 gallons of fuel produced with approximately 134,632 gallons produced as in-spec diesel, and 36,093 gallons produced as naphtha. This represents a 42.7% increase in total gallon production as compared to the quarter in which the company previously achieved its highest recorded production totals, the fourth quarter of 2012. The company recycles waste plastic into liquid fuels with its proprietary Plastic2Oil technology.

Recovering the energy value, which is quite high, in scrap plastics is critical to energy savings programs as well as to supporting recycling programs. Let's hope that building and construction companies like Trex, along with many others that use recycled plastics to make their wood-alternative decking/railing and roofing products, as well as JBI and others, continue to experiment and find new ways to capture and re-use the valuable energy that lies in the plastics products we produce. Maybe paying more for the recycling of these products is key to pushing these HDPE film programs into high gear.