Conscious Choice: The Age of Green Plastics May Be Coming Soon

May 2002 | News of the Earth

The Age of Green Plastics May Be Coming Soon

by Dave Aftandilian

When I was young, my mom and her mom used to host Tupperware parties at our house. They’d invite dozens of women from the neighborhood to see the newest brightly colored plastic wonders, such as stackable, airtight food canisters or toys for preschoolers. I still use a Tupperware sandwich container, one that’s probably just about as old as I am, if not older. Nowadays, of course, you can buy microwave — and dishwasher-safe plastic containers in your local supermarket. Indeed, just about every room in the average home or workplace showcases the wonders of plastic, from pens, keychains, and rulers to computers, food processors, and plastic wrap.

As E. S. Stevens points out in his new book Green Plastics: An Introduction to the New Science of Biodegradable Plastics, we truly live in the Age of Plastics. In the United States, more than 1.5 million workers produce or distribute more than $300 billion worth of plastic-related products annually. Worldwide more than 200 billion pounds (100 million tons) of plastics are made each year — 80 billion pounds in the United States alone. What do we use all that plastic for? In this country, the largest single use by far is in packaging — bottles and other containers, plastic sheeting or wrap, and more — which accounts for about 30 percent of annual plastics production. About 15 percent of plastic is used for heavy-duty building materials, and another 14 percent for consumer products including toiletries, toys, and eating utensils. Other plastics are used in transportation products, furniture, agriculture, and various biomedical applications.

The wonders of plastics bring a few horrors along with them, though. For one thing, we’ve engineered plastics to be sturdy and durable. That’s great for the products we want to use for decades, like my Tupperware sandwich container. But what about all the things most people use once or a few times and then throw away — fast-food containers, soda bottles, milk jugs, razors, sandwich bags, and so forth? They don’t look quite so wonderful sitting at the bottom of a landfill, which is where most of them end up. According to Stevens, plastics account for about 18 percent of the total volume of municipal solid waste in the United States, and if you subtract the organic waste that can be composted (food scraps, yard waste, etc.), plastics make up 30 percent of the remaining weight and up to one-half of the remaining volume. Most of that plastic waste will never decompose.

While a few plastic products are collected and recycled (mainly beverage containers), even then there’s little point to recycling them if there isn’t a market for the reclaimed fibers. Right now it’s cheaper to make new plastic soda bottles than to use recycled plastic, for instance. And the vast majority of plastics are difficult if not impossible to recycle using conventionally available technology.

Another big problem is that almost all plastics are made from oil, natural gas, and/or coal. These sources are nonrenewable; they are the very same fossil fuels that supply most of our energy needs. While plastics only take up 6 to 8 percent of the total oil and gas we use (4 to 5 percent as source material, or feedstocks, for plastic; 2 to 3 percent for the energy to process those feedstocks), that fraction will look more and more significant as we begin to exhaust our oil and gas supplies. Also, most plastics must be produced at high temperatures through processes that use chemical solvents, some of which are carcinogenic.

But there are ways to produce plastics from renewable sources — plastics that are biodegradable, compostable, and in some cases almost completely reusable. Stevens calls these "bioplastics." While this may sound like a radical new idea, it’s actually a practical old idea that got sidelined by the craze for synthetic plastics. Natural resins such as amber and shellac have been known since Roman times, and various bioplastics were common in the nineteenth century. For instance, ebonite — a black, vulcanized form of natural rubber — was used for combs, buttons, electrical insulation, and other products. And the English inventor Alexander Parkes made a variety of pressure-molded objects from collodion, or Parkesine, an early precursor of celluloid. Starting in the 1910s, Henry Ford experimented with plastics made from agricultural materials for car parts such as knobs, steering wheels, and dashboard panels — in 1941, he introduced a prototype car body made entirely from soy meal and cellulose (the war and the significant amounts of formaldehyde required put a stop to the research). Cellophane, made from the cellulose in wood or cotton, is still used in food packaging today.

How do bioplastics work? Plastics are made from polymers, long chains of hydrocarbons joined together. As Stevens describes it, the first step to coming up with a green plastic is to find sources of abundant polymers in nature, or natural polymers that can be made in large quantities through fermentation by bacteria and other microbes. These polymers also must have the right physical properties for the desired finished product. For instance, if you want to make bottles or plates, you need polymers that can be shaped when heated (thermoplastic polymers). You also need to make sure not to add chemicals during processing that would keep the plastics from being biodegradable.

It turns out that there are a surprisingly large number of sources of natural polymers just waiting to be exploited. Starches, for instance, are abundant and cheap. Cellulose would also be a good source, as it is so widely available in plant parts — in fact, using cellulose could turn common agricultural wastes such as straw and corn stover (the stalks, leaves, and husks left over after the cobs have been harvested) into valuable feedstocks for plastics, giving farmers some badly needed additional income. Currently it is difficult to extract cellulose from such wastes, but research is ongoing. (Perhaps some of the bacteria that digest cellulose in the stomachs of cows, goats, and other ruminants will provide a clue.) Various polyesters can also be obtained from bacterial fermentation.

Combining various natural polymers with other ingredients may end up being the perfect recipe for green plastics. For instance, blends of starch, cellulose, and calcium carbonate (limestone) have shown promise as plastics for use in low-cost, disposable, compostable food packages, such as those used in the fast-food industry. The starch could come from as homely a source as the potato peels left over from making french fries. Composites of polymers from starch and proteins satisfy the food requirements of hogs and other farm animals, so plastics made from these sources could be pasteurized and turned into animal feed — "a rather extraordinary example of recycling waste," as Stevens rightly describes it.

Certain technical hurdles remain. Starches tend to be water soluble and only moderately strong, and polyesters from bacterial fermentation are quite expensive. But many bioplastics are almost ready for commercial production already. What’s keeping us from using them? Currently only starch-based plastics are cost competitive with plastics from synthetic resources. As fossil fuels run out and space for waste disposal becomes scarce, this situation should change. In the meantime, the government could help in a number of ways. First, it could tighten the restrictions on the use of plastics, perhaps requiring that plastics used in packaging be made of biodegradable materials to reduce waste. Second, government agencies from the national to local levels could jump-start the market for green plastics by requiring that plastic items supplied to these agencies be made of bioplastics. Third, the government could provide increased funding for research and development of bioplastics — for instance, through the USDA’s already existing National Center for Agricultural Utilization Research in Peoria, which has conducted groundbreaking research on using starch and other materials from agricultural products to produce bioplastics.

But the real impetus for developing bioplastics, Stevens argues, must come from private industry. Many companies are already discovering that adopting sustainable practices such as reducing waste saves money in the long run, partly because companies that turn green now will be in a much better position to deal with — indeed, even profit from — future environmental regulations that are likely to be more restrictive than the current rules are. Because bioplastics can be manufactured at lower temperatures and without the use of chemical solvents, they offer cost savings in terms of reduced energy and chemical inputs. And the natural feedstocks used will eventually be much cheaper than fossil fuel-based synthetic compounds.

"Most of all," Stevens writes, "what is needed for bioplastics to find a place in the current Age of Plastics is a paradigm shift. ...In ignoring nature’s way of building strong materials we have, for many applications, overengineered our plastics for stability, with little consideration of their recyclability or ultimate fate, and have ended up transforming irreplaceable resources into mountains of waste. There is another way. Plants and animals have been producing strong, pliant materials for eons. ...When the plants and animals die, the materials degrade naturally, so that they can be recycled. ...We can take nature’s building materials and use them for our purposes, without taking them out of nature’s cycles. We can be borrowers, not consumers, so that the process can continue indefinitely."

Recommend this page to a friend

Top Ten pages recommended to friends: