Bioplastic: The Water Bottle That Won’t Live A Thousand Years
Plastic: it’s pretty inescapable. Unless you are a Tibetan monk living on a mountain top or a Maasai tribesman in the wilderness of East Africa, chances are, you’re swimming in plastic. It’s not news that the landfills of the world are also miles deep in the stuff, and will continue to be hundreds of years from now, since petroleum-based plastics are estimated to take somewhere between 500 and 1,000 years to break down in today’s landfill environments. According to the Society of Plastics Engineers, about 200 million tons of plastic are manufactured worldwide each year; 26 million tons of it in the U.S. alone. And according to the Environmental Protection Agency, only 5.8 percent of that 26 million tons are actually recycled each year, leaving the rest to the country’s landfills.
In an effort to control the amount of plastic getting dumped and sitting around for the next millennium or so, many parts of the world have put in place guidelines, restrictions and even outright bans on some plastic products, including the ubiquitous plastic supermarket bag. (In California, it’s a legal requirement for supermarkets to have recycling programs in place for plastic bags.) In parts of Europe, the bags are actually illegal. Even if we rid ourselves of the supermarket bags, it still leaves hundreds of millions of tons of waste plastic from consumer and industrial use kicking around until the thirty-first century.
When it comes to plastics, the cutting-edge news, of course, is bioplastic: organic plastic made from renewable sources such as corn starch, sugar cane or pea starch. Bioplastics, which break down into the sub-categories of cellulose, starch, polylactic acid (PLA), poly-3-hydroxybutyrate (PHB), and the newest polyamide 11 (PA11), sit opposite the traditionally produced petroleum-based plastics which will still be with us when our ancestors are getting around town via flying cars. By definition, however, not all bioplastics decompose easily: you wouldn’t want your bioplastic-based cell phone or car to begin composting while you’re using them. Rather, the green factor for some bioplastics comes from the fact that they are made from sustainable materials rather than fossil fuels. (Some scientists use the terms “bio-based” to discuss bioplastics that are sourced from renewable materials but do not easily biodegrade.) Even bioplastics that do degrade generally do so only in carefully controlled industrial composting environments rather than while lying on a trash heap (traditional landfills are a very poor environment for decomposition, because they are often built to be air- and water-tight to avoid spills and smells, which isn’t a very inviting environment for the friendly bacteria that aid decomposition).
There is, in fact, a worldwide standard for the definition of what constitutes a true bioplastic. The standard, called EN13432, is maintained by the International Organization for Standardization, or ISO. To be in compliance with EN13432 standards, the compostable variety of bioplastic must show 90 percent biodegradation of the materials in a commercial composting unit within 180 days. Biodegradable bioplastic enthusiasts point out that these newer materials would enable nearly all household garbage to be composted: with the removal of things like aluminum foil and glass from household garbage by residents, nearly everything else – food scraps, most paper products and bioplastics – could be aerobically composted together without the need for costly separation and cleaning of organic residue from plastics, which often renders them unsuitable for recycling (think about that next time you drop that plastic squeeze bottle of ketchup into the blue bin without washing it out first).
Plastic supermarket bags and food wrappers aside, the industrial world has found a nearly unlimited number of applications for bioplastics. Today, they are starting to show up in everything from cell phones to building materials to carpet fiber, though in products like these, they are more likely to be merely bio-based rather than actually biodegradable.
In the meantime, research labs all over the world are busy working with newer bioplastics and broader applications for them. One of those places is at the Department of Plant Agriculture at the University of Guelph in Ontario, which now houses the new Bioproducts Discovery and Development Centre. At the Centre, a team of plant biologists, chemists and engineers, led by Dr. Amar Mohanty, work together to investigate and commercialize biomaterials such as switchgrass, wheat, soy and corn starch to create new bioplastics for the manufacture of everything from packaging to furniture, wind turbines and automobiles. The Centre has a testing lab with equipment specially designed to test the durability and commercial potential of the end products. The team is currently working on a project to use biomass from soybeans to make the blades of wind turbines.
Outside the research labs and in the earthier manufacturing sector, however, there are worries that the rise of bioplastics (and perhaps future bans on petroleum-based plastics) would necessitate a complete overhaul of factories that produce plastic-heavy products such as packaging, healthcare supplies and disposable cups and cutlery. The worries may be misplaced. One of the most common bioplastics, PLA (polylactic acid), has properties that so closely resemble petroleum-based plastics such as polyethylene and polpropylene, it can be successfully processed on factory equipment designed for the production of conventional plastics, eliminating any need for factory modifications. PLA is a starch-based plastic generally produced from crops such as corn starch or sugarcane, and it’s usually the bioplastic of choice for the production of water bottles, plastic cups and food packaging.
Issues about the cost of bioplastic production compared with traditional plastics are still a concern, of course, not to mention the
necessity of building specialized industrial composting facilities to deal with the bioplastics after use. A Dutch scientists named Jean-Paul Meijnen may have taken some important steps toward solving the first part of the problem: cost of manufacture. Meijnen claims to have trained specialized bacteria to consume the sugars in food wastes and convert them into bioplastics. Meijnen started with a bacterium called Pseudomonas putida S12 to see what it could do with the three primary sugars in biowaste: glucosez, xylose and arabinose. At the start of the experiment, Pseudomonas was able to convert only glucose, and not the two others. Meijnen then modified the bacteria by injecting two enzymes from another bacterium, the not-so-friendly E. Coli, into Pseudomonas. The modification provided Pseudomonas with the ability to ingest and convert all three sugars, resulting in complete conversion of the biowaste. The result was that the bacteria ate biowaste and produced a bioplastic substance called para-hydroxybenzoate (pHB), which is widely used in both the pharmaceutical and cosmetic industries.
Going mad for bioplastics, of course, will come with its own set of environmental concerns, even if increased use does cut the carbon footprint of the plastics industry. For starters, the enormous amount of biomass (plant materials) that would be needed may cause farmers to begin planting crops for the manufacture of plastics rather than food, which could cause global food shortages. This is a concern that has already proven to be salient in the growing of corn for bio-ethanol production. Secondly, the increased agricultural cultivation for bioplastics could lead to devastating environmental side effects such as deforestation, degradation and erosion of soil, pesticide and herbicide use (for killing weeds) and increased water usage.
Many critics of bioplastics say it’s actually a matter of carbon emissions. When bioplastics decompose, like anything else that decomposes, they release carbon, which adds to worldwide global emissions. With traditional plastic which does not break down (not for a very long time, anyway), the carbon used in the manufacturing process remains locked in the plastic and doesn’t contribute to greenhouse gas emissions. Counter-critics, however, point out that when the biomass materials used to make bioplastics grow as plants, they suck up (sequester) carbon, so when the carbon is later released during decomposition, there is no net gain of carbon.
One thing we can be certain of is that bioplastics will be a big part of our future (along with all those water bottles, diapers and food storage bags in the landfills). Research group Frost & Sullivan, in its 2009 “Global Bio-based Plastics Market” study, wrote that many bioplastics companies are currently in the process of transitioning from laboratory and pilot production to market entry and commercialization of products. Researchers noted that the range of products using bioplastics will continue to expand: Frost & Sullivan has pegged the 2008 worldwide global bioplastic market at over $750 million (which sounds pretty modest), but expects that figure to double to nearly $1.5 billion in 2015. A recent report from BCC Research pegs the expected growth rate somewhat lower, but still quite brisk, at about 41 percent.
And this is a good thing. Otherwise, it’s depressing to think that though our own ancestors of a thousand years ago left us cathedrals, castles and illuminated manuscripts, we’re on track to leave our ancestors, one thousand years from now, a planet covered with miles-deep landfills of plastic water bottles and supermarket bags.