The world is awash in single-use plastics. Plastic lasts about forever. Not only does it eat up landfill space, but it has also made its way into the oceans. And it all comes from fossil fuels, which have their own environmental drawbacks.
In recent years, companies have started to explore plant-based plastics. One has even introduced a paper beer bottle. These companies tout numerous environmental benefits of plant-based plastics. Can bioplastic bottles help solve our plastics problem?
PET, the kind of plastic used for most drink and food packaging, works very well. It is strong, lightweight, versatile, and inexpensive. It can stand up to acids in foods and the pressure of carbonated drinks without breaking down.
If bioplastics can ever replace petrochemical plastics, they will have to perform just as well and just as economically. And they must demonstrate no offsetting environmental problems.
Currently available plant-based plastics
Two biodegradable plant-based plastics are in common use today. Polyhydroxyalkanoate (PHA) usually comes from sugars made by algae. Polylactic acid (PLA) usually comes from sugars in crops such as corn and sugarcane. PHA costs ten times as much as PLA. In food packaging, it is mostly used as the coating for paper cups.
Neither of these bioplastics match the characteristics that make conventional plastics so useful. And even PLA costs considerably more than conventional plastics. Bioplastics currently have a global market share of $9 billion, which pales in comparison to the $1.2 trillion plastics market.
The latest hype surrounds a different bioplastic, polyethylene furanoate (PEF). Chemically, it resembles PET more closely than either PHA or PLA.
PET is 32.2% monoethylene glycol (MEG) and 67.8% purified terephthalate (PTA) by weight. Coca-Cola announced a plant bottle in 2009 with up to 30% plant-based material, with the rest being recycled plastic. In essence, their formula used a plant-based MEG, but no plant-based PTA existed.
PEF replaces the PTA in PET with furan-dicarboxylic acid (FDCA) made from plant feedstock.
Besides being biodegradable, PEF has some advantages over PET. It has greater tensile strength and gas barrier properties. It can be filled with hotter liquids than PET can bear.
Still, it’s not likely to replace PET. It is not yet produced at commercial scale. Not only is it expensive and energy-intensive to produce, but it is also a contaminant if it gets mixed with PET in the recycling stream. So far, PEF is mostly used for multilayer barrier containers, such as coffee cups.
We have paper coffee cups. Why not paper bottles? In either case, they require some kind of plastic barrier between the liquid and the paper. That’s why paper coffee cups are not recyclable using current technology.
Carlsburg has recently announced the first paper beer bottles, made from a wood-based fiber shell lined with PEF. It claims they offer the same taste and fizziness of glass beer bottles. So far, it doesn’t have a plant-based cap but expects to have one by 2023. It is making 8,000 trial bottles to ship to customers in eight European markets.
Carlsburg has been working on the paper bottle since 2015. Other companies working on paper bottles include PepsiCo and Unilever. In principle, a paper bottle with a PEF liner ought to be biodegradable.
Biodegradable is not enough
All these plant-based plastics are biodegradable. Unfortunately, biodegradable isn’t the same as compostable. At least, not in a home compost pile. They are technically compostable, but only in industrial composting facilities. Not many exist. Not all accept bioplastics. Therefore, most people can only dispose of these bioplastics the same as other plastics: the trash, littering, or recycling.
Unfortunately, all these plant-based plastics become a problem in the recycling stream. They would have the code number 7, which identifies them as “other,” plastics not common enough for their own code. There is virtually no market for them. PET, on the other hand, is easy to recycle once it actually gets collected. But if bioplastics somehow contaminate a batch of PET, it becomes fit only for the landfill.
The problem of feedstock for bioplastics
Proponents of bioplastics claim that they have a lower carbon footprint than conventional plastics. They fail to account for the energy it takes to grow the crops that provide the feedstock. Bioplastics may actually have a higher carbon footprint than conventional plastics.
Since bioplastics come from plants, the plants must come from somewhere. Bioplastics cause the same problems as ethanol and other biofuels. Land used to grow crops to make them is land taken out of use for food production, but it still requires fertilizers and pesticides.
As far as PLA is concerned, it should be possible to make it from food waste, municipal solid waste, or paper waste. The George W. Bush administration championed making ethanol from cellulose. It is a possible feedstock for PLA, but cellulosic bioethanol hasn’t yet overcome severe technical, economic, and legal challenges.
Avantium, maker of the PEF liner for Carlsberg’s paper bottles, claims that its FDCA can come either from food crops or agricultural residues. Coca-Cola seems to be touting a totally plant-based PET, using a plant-based PTA instead of FDCA. It, too, claims it can use such feedstock as sawmill waste. If so, it marks a major development in cellulosic ethanol. And Coke further claims that it can make MEG directly from sugar without using ethanol as an intermediary.
Using algae to make PHA doesn’t present the same problems as using sugar for PLA or PEM, but the technology to grow and use the algae cannot yet be scaled to a level that brings the costs down.
The problem of hype about bioplastics
The hype around plant-based plastic suggests we can use it, throw it away, and it just disappears without causing any trouble.
Even if we can devise a bioplastic that works as well as conventional plastics and costs no more, it won’t solve all the environmental problems society’s wasteful ways cause. In this regard, bioplastics haven’t notably improved since I first wrote about them several years ago. The hype amounts to greenwashing.
Single-use, disposable products are an environmental headache. Period.
Environmentalists frequently point out that plastic recycling as currently practiced is a sham. We need to produce much less plastic in the first place and, in the meantime, learn how to recycle it more effectively.
In the US, by the way, we recycle less than 9% of plastic. Europeans manage to recycle more than 40% of plastic. Some European countries charge deposits on plastic bottles. Norway has used them to achieve a 97% return rate.
In other words, Europeans recycle plastic much more effectively than we do but not effectively enough that recycling can become a real solution to the problem of plastics.
Here are some necessary steps:
- Replace as much plastic packaging as possible with compostable materials—materials that don’t require industrial composting.
- Design products with effective recycling in mind.
- Scale up recycling infrastructure in moderate- and low-income countries, the source of most of the plastics in the oceans.
- Eliminate exporting plastic waste and thus force exporting countries to come up with their own solutions to the plastics problem.
- Take the burden of collecting and processing of recyclables from governments and institute extended producer responsibility
8,000 green bottles … Carlsberg trials fibre beer containers / The Guardian. June 22, 2022
Coca-Cola collaborates with tech partners to create bottle prototype made from 100% plant-based sources / Coca-Cola. October 21, 2021
Plant-based PET, paper bottles and PEF / Bruno Rey, The Packaging Blog. November 2021
Why bioplastics will not solve the world’s plastics problem / Jim Robbins, Yale Environment 360. August 31, 2020