The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change

One Word: Plastics

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The title for this post is, of course, a quote from The Graduate, but  the line of inquiry that got me writing today was actually triggered by a different movie. In It’s a Wonderful Life, one of George Baily’s friends tries to get him to invest in a company than makes plastic from soybeans. This detail is irrelevant to the plot–the important thing for the story is that the suggestion to invest in something functions as more pressure for George to settle down, which is does not want to do. That the “something” is plastics is arbitrary, and I ignored it for all of the 948,000 times I’ve seen the movie.

Until this year, when I saw it for the 948,001st time, and thought–wait, soy-based plastic? In the 1930’s? (the movie was actually made somewhat later, but the scene is set before World War II) If they had soy-based plastic then, why do we still bother with petro-plastics now? Why are bioplastics always talked about as if they were new, when we’ve obviously had them for at least ninety years?

The short answer is that “plastic” is not one material but several, and the types of bioplastics that existed ninety years ago were not very useful. They’re not the plastic we’re looking for.

Let me elaborate.

A Primer on Plastics

“Plastic,” originally an adjective meaning “flexible,” has come to refer to a any of a large group of organic polymers (“organic,” in this case, means including the element, carbon). A polymer is a a very large molecule made by stringing together lots of smaller molecules, or monomers. Not all polymers are plastics–DNA, for example, is a polymer made out of protein.

Depending on the polymer, how it is processed, and what additives it contains, a plastic might be clear or opaque, strong or weak, flexible or brittle, cheap or expensive, toxic or non-toxic, biodegradable or not biodegradable.Thermoplastics are made of chain-like polymers and melt and flow when heated–that makes them relatively easy to recycle. Thermo-set plastics are made of web-like polymers and do not melt. They are very difficult to recycle.

Plastics can be synthesized from various feed stocks, including petroleum, natural gas, sugar, and plant-derived oils. Some plastics can be made from either petroleum (or natural gas) or recently-living plant-matter–and the result is chemically identical either way. That is, being made from petroleum doesn’t make a plastic automatically bad, and being made from recently-living plant doesn’t, all by itself, make a plastic good.

Some plastics can only be made from a fossil fuel, but do have bioplastic analogues. But since the analogue is chemically distinct, it won’t necessarily have the same performance characteristics and might be both more expensive to the consumer and less useful.

The long and the short of all of this is that “plastics” is a very broad category and you really have to know which plastic you are talking about before you can say much of anything about it.

The Problem with Green Plastics

Because different plastics have different properties and different advantages and disadvantages, looking for an “eco-friendly” plastic is a good way to get confused or even scammed. Apples get compared to oranges through marketing, and the point of the whole exercise can get lost in the shuffle, unless you remember to think of plastics as a whole group of materials.

Ideally, for each petroplastic on the market today, we want a bioplastic equivalent that does the same job at a competitive price and then biodegrades when we don’t need it anymore.

And indeed, as noted, some petroplastics do have bioplastic equivalents, some of which are even chemically identical. Use of bioplastics would at least get us away from fossil-fuel feed stocks, a definite good thing, even if everything else remained the same. Remember, it is demand for fossil fuels, including demand by the plastics industry, that drives fracking, oil spills, and pipelines being put in where they should not go.

But bioplastics are still synthetic polymers, which means hardly anything can eat them.  They can stick around in the environment forever, clogging up animal digestive tracks and otherwise causing havoc, just like petroplastics can. And some plastics of either origin can shed their component monomers, many of which are toxins.

There are biodegradable bioplastics and there are also biodegradable petroplastics. In theory, either would be a good thing–even if the product were still made from petroleum, reducing the amount of plastic floating around in our oceans forever would be an improvement.

The problem is that true biodegradable plastic–as in, you could throw it on the ground and it will become soil in a reasonable amount of time–is rather hard to find. What you get instead is various versions of disintegration, referred by a  collection of terms that are precisely defined by industry leaders.

Degradable means the plastic breaks up into lots of little, hard-to-see pieces that you can ignore if you want to. The term does not say anything about what happens to those little bits–they could just go on being plastic, which is very bad, because eventually they end up in the oceans where they get mixed up with the plankton that forms the basis of oceanic food webs. Already a really scary proportion of ocean life have tiny bits of plastic in their bodies. Remember that, next time you eat ocean-caught fish.

The first plastics marketed as “biodegradable” in fact did exactly that–broke up into tiny pieces of permanent plastic. These days industry standards require stricter labeling, but fancy terms such as photodegradable and oxydegradable still just refer to how any why plastic breaks down into bits–they promise nothing as far as avoiding the Tiny Plastic Apocalypse.

If you want something that actually breaks down because microorganisms digest it, you’re looking for biodegradable plastic. And it does exist, but that term promises nothing about how healthy the resulting soil is–you need compostable plastic if you want soil that, say, does not kill plants.

And even compostable plastic might not break down unless it is processed in a large-scale, municipal composting facility which, by the way, hardly any municipalities actually have. Your back-yard compost pile might not work, and throwing the stuff in the ocean (which is what will happen to virtually all plastic eventually anyway, even if it gets delayed in a landfill for a few thousand years first) definitely won’t work. You’ll get tiny bits of plastic again.

Even under ideal circumstances, I’m not sure that compostable plastic actually avoids the tiny-bits-of-plastic scenario. The standard tests involve sieving the composted product to make sure all the pieces are small, testing for the presence of heavy metals, and trying to grow plants in it–but they don’t test for the chemical signature of the synthetic polymer itself. Some plastic could get through.

Some people argue that biodegradable/compostable plastic is actually a bad idea. It’s not going to get a chance to compost, and a lot of it probably gets dumped in with plastic recycling by mistake, where it can contaminate whole batches. Some compostable plastics are recyclable in theory, but virtually no facilities are equipped to handle it.

I would not say compostable plastics are bad–rather, I’d say this is another example of why we should not try to simplify our choices into blanket pronouncements: PLASTIC=BAD, COMPOSTABLE=GOOD, etc. There are some circumstances under which a compostable plastic might be the better option. Other times, it might not be.

At this time, the most effective thing we can do is probably to minimize the use of all plastics, while continuing to call for compostable bioplastic options for those times we’re unwilling to do without. Half of the oil used in plastics production actually goes into energy generation, not feed stock. If we can shift the industry over to renewable energy, we can substantially shrink the carbon footprint of plastics.

Bioplastics, Past, Present, and Future

The first plastics–cellophane and rayon–were bioplastics. They still have a place in the market, but the market has grown to include many needs that these products can’t meet. Newer, petroleum-based plastics can and do. Much of the early promise of bioplastics never panned out–Its a Wonderful Life is fiction. Henry Ford’s famous attempt to make a plastic car using soybeans actually involved soy fibers in a phenolic resin. Phenolic resin is Bakalite, a petroplastic.

Over the years, hardly anybody has ever been able to make bioplastics work as a business model except, again, in niches. Modern environmental awareness might expand some of those niches, and ongoing technological development might give us new bioplastics that function better as competitive analogues to some of the petroplastics. Various authors have analyzed the probable economic effects of a shift to bioplastics–production would likely shift to the Midwest, for better access to raw materials, for example.

Sooner or later, we’re going to have to get off fossil fuels entirely. When that happens, bioplastics will be all we have–and we have the technical know-how to make the conversion already. It may be comforting to know that the future need not leave us without plastics, since they are very useful materials for some things–medical equipment, for example. The downside is that we will still be faced with the problem of plastic waste–barring a radical change in technology, it seems likely that even the most compostable bioplastics will still require specialized circumstances to break down. The key will be to keep plastic use to a minimum and to diligently recycle or compost all used plastic items.

The important thing to remember is that, however ubiquitous plastics are now, they didn’t exist much more than a hundred years ago, and most are more recent than that. Most uses of plastics today are simply unecessary.

 

 

 

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Author: Caroline Ailanthus

I am a creative science writer. That is, most of my writing is creative rather than technical, but my topic is usually science. I enjoy explaining things and exploring ideas. I have one published novel and another on the way. I have a master's degree in Conservation Biology and I work full-time as a writer.

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