Confusion about bioplastics is rife, and very peculiar notions about these materials abound. With sustainability at the forefront of so many business agendas these days—a quick look a the number of sessions devoted to the subject by the NPE and ANTEC this year will show just how prominent a theme this has become—a very brief review of what bioplastics are, and, especially are not, seems in order.
The first bioplastics, while not very successful as commercial materials, were nonetheless hailed with—in retrospect—touching naivety as the ultimate solution to plastic waste. The end of life was simple: they would degrade and disappear. Goodbye, toxic emissions when burned, goodbye litter, goodbye landfill problem; nature would take care of the problem.
And from then on, things began to get complicated.
In the first place, it rapidly became clear that the term ‘bioplastics’ needed further clarification. Soon, we had biobased materials, biodegradable materials, compostable materials, recyclable biomaterials, and various combinations of all of the above.
As it turns out, materials that are biodegradable are not necessarily compostable. According to the FTC Green Guide, a product or package qualifies as biodegradable if it “completely breaks down and returns to nature, decomposing into elements found in nature within a reasonably short period of time after customary disposal.”
For products to qualify as certified compostable, all the materials in the product or package must “break down into, or otherwise become part of, usable compost in a safe and timely manner in an appropriate composting program or facility, or in a home compost pile or device.” In other words, it’s a controlled biodegradation process. The big problem is that not all biodegradable products will degrade in a “timely” manner, making them unsuitable for composting, and some will disintegrate into elements that are unacceptable in compost, likewise rendering them composting no-no’s.
Compounding the problem, there are biomaterials that can be industrially composted, but not home composted, which means that efficient collection systems are needed to make sure these materials end up taking the appropriate end-of-life route. Yet deciding which route is the right one can also be a challenge. PLA, for example, can be industrially composted—sometimes. Heat-resistant PLA is not compostable. It can, however, be chemically recycled into lactic acid. For that matter, so can regular PLA. The point is, the infrastructure for an adequate recovery of PLA is largely absent—as it is for the handling of all bioplastics. An entire recovery infrastructure is needed for the collection, sorting, composting, or recycling of these materials. To date, such facilities are woefully lacking.
And then there’s the uncomfortable fact that non-compostable biodegradable materials generally won’t biodegrade in landfills, as landfill conditions fail to provide exposure to the sunlight, air, and moisture needed for degradation to occur. This is intentional, to avoid side effects of degradation such as ground water pollution, methane gas emissions, and unstable soil conditions. What it actually means is that, contrary to what is commonly believed, these materials are going nowhere.
A further confusing issue is the emergence of the so-called biobased materials, defined by the American Society for Testing and Materials (ASTM) as follows: A material is an organic material in which carbon is derived from a renewable resource via biological processes. Biobased materials include all plant and animal mass derived from CO2 recently fixed via photosynthesis, per definition a renewable resource.
However, materials carrying the label biobased do not necessarily contain only renewable resources. And biobased materials are not per definition biodegradable. In fact, they are very likely not to be. These materials generally end up either being recycled or incinerated.
In short, when talking about these materials, in particular regarding their end-of-life options, it’s important to understand that not all bio(based) plastics are created equal. Yet what is even more important is to understand that the point about bioplastics is not their end of life, but their life itself.
Bioplastics are increasingly a viable proposition. After all, plants are a renewable feedstock. Petroleum is not. Next to offering a way to reduce our chronic dependence on petroleum, many bio-based feedstocks have fewer problems with price volatility, compared to oil. Moreover, the industry is rapidly moving away from food crops toward the use of waste and inedible biomass. Also, reports from the European Bioplastics association say that life-cycle analyses show that bioplastics can reduce carbon dioxide emissions by 30%-70% compared with petroleum-based plastics.
Bioplastics can indeed offer a valuable alternative to conventional plastic materials. It’s time to take them seriously and to create the necessary conditions and facilities to apply the principles of Reduce, Reuse, Recycle, and Recover to these materials, as well. In some cases, thermal recycling, aka incineration, may well even offer the best option.
The real waste is to sit around and hope they’ll magically fall apart.