In the ever-changing world of consumer products, “bio” is gearing up to be the new buzzword (or prefix – take your pick) of the decade.
More and more products are hitting the shelves that are made of bio-based materials and/or are biodegradable. Simultaneously, confusion and questions about what to do with these products are rising at the same rate which they are landing in our grocery carts.
What do these terms mean? And more importantly, how do they affect you? Earth911 hit the streets to find out just that – and ended up learning a whole lot more.
Warning: This article is about to get a bit technical. But, we promise to distill it down the basics of everything you need it know. Put on your thinking caps!
Definitions You Have to Know
So, let’s start with a few terms you need to know:
Bio-based plastics or biopolymers – These are plastics made with materials that can be grown and are renewable. “‘Bio-based plastics’ means it’s made from a raw material that’s a renewable material,” said Keith Christman, managing director of plastics markets for the American Chemistry Council (ACC). Some bio-based plastics can be recycled in our current system, while others cannot.
Biodegradable – Some materials are biodegradable, meaning they are capable of being decomposed by the action of biological agents, especially bacteria. But don’t confuse these first two terms. “Some bio-based materials are not biodegradable,” Christman added.
For example, according to Christman, Dow is producing ethylene from sugar cane (used to make polyethylene or a component of plastic #1), and the material is recyclable in today’s current recycling stream, but not biodegradable. Most biodegradable plastics cannot be recycled in the current stream.
Compostable – This term implies that a product will break down in a composting environment (more to come on this), but typically implies that a product should be composted in an industrial facility, not at home. There are new products on the way that may defy this particular aspect of “compostable,” but for our discussions, keep this in mind.
Life cycle assessment – Also referred to as an “LCA,” these reports look at various aspects of a product’s production, such as solid waste, energy consumption and greenhouse gas (GHG) emissions. These reports, while they vary product to product, typically give us a full-circle look at what the overall impact really is of a product’s manufacturing.
Polylactic acid – Also known as “PLA,” this material is a bio-based plastic that is typically biodegradable in a commercial composting system. It is one of the most prevalent biopolymers on the market currently.
These concepts represent a wide array of applications and innovation in the plastics market today. “A lot of these things show that plastics are innovative. They are carbon-based materials and can be made from a variety of carbon materials.
“In the U.S., we traditionally use natural gas,” Christman said, noting that approximately 79 percent of the plastics manufactured in the U.S. are made from this particular fuel source. And while biopolymers and biodegradable materials still constitute a fraction of the overall market, their presence is growing.
How Things Biodegrade
With all this discussion about “biodegradable,” the take-home message is that we should just be able to leave a bottle out in a park or bury it in the yard and it will decompose, right? Well, not exactly.
“When the consumer hears ‘biodegradable,’ often times they think it’s a material that you can throw out the window of your car and after one good rain, it will be back to nature, and it will fertilize the roadside,” said Richard C. Bopp, senior material scientist for Natureworks, LLC, one of the leading producers of PLA.
“Saying ‘biodegradable’ is not specific enough to be useful, and it leads to all kinds of misunderstandings,” he added.
Left to its own devices, PLA will not simply biodegrade on its own – which may be surprising, but is actually a benefit. “Thank goodness it’s that way […] Otherwise you’d have a stability problem with your plastic – it’s like things going bad in your refrigerator,” said Bopp. Imagine mold growing on your cell phone, and you’ll understand why the basic concepts of “biodegradable” (a la the now-fuzzy fruit from last week’s lunch) don’t apply here.
So how does PLA actually biodegrade? Here’s how it works, according to Bopp:
- PLA cannot be metabolized by microbes. But the lactic acid, which is half of its molecular unit, can very easily be broken down.
- In the environment of a compost pile, which is typically around 60 degrees Celsius (140 degrees Fahrenheit) and 90 percent relative humidity, bonds in the PLA molecule are susceptible to a process called “hydrolysis,” which means being broken down by water.
- Because of this, water molecules come in and sever these bonds, ultimately freeing the lactic acid in the PLA molecule, meaning the microorganisms in the pile now have food to consume.
- The lactic acid is metabolized by the microorganisms, and water and CO2 are what remain from the original plastic.
According to Bopp, these biodegradable properties make more sense in some plastic applications over others. “I often like to say ‘why would I want to turn a perfectly good piece of plastic into dirt?’ […] Well, I’d want to turn it into dirt if the cost for recovery for recycling was just so high that it didn’t make sense to recover it as a plastic.
“For example, if I use the PLA for plates, knives, forks and spoons […] it may not make environmental or economic sense to recover dirty plastic covered with rotten food. It may make more sense, as it’s combined with paper napkins, paper cups, food waste, to compost it. And especially at a place like a theme park where you have gardens and use that for landscaping, it makes a lot of sense to compost bioplastics in those situations,” he said.
And with today’s PLA, what would constitute a less meaningful use of the material?
For illustrative purposes, Bopp uses the example of the instrument panel on a car’s dashboard. “Of course, it’s a double-edged sword, because if you have an instrument panel in a car made out of Ingeo PLA, as it is today, and it’s parked in Houston in the summertime, the interior of that car can get awfully close to [the conditions in] a compost pile,” he said. “For every 10 degrees Celsius (50 degrees Fahrenheit) increase in temperature, most reactions double in rate, so temperature is very important. I’m not saying PLA will never be used for an instrument panel, but we’ll have to figure out some stabilization developments.”
What’s the Holdup?
So, to recap so far, we’ve learned the basics of what constitutes a bio-based material and how breaking down PLA works. And, we can grow all of the materials we need for plastic right here at home in the U.S. So why isn’t all plastic made out of plants?
Getting to a Commercial Composter
One major hurdle right now is that finding a commercial composting facility is difficult, as they are are not as widely available and few cities across the U.S. have composting services. And, according to the National Resource Defense Council (NRDC), only 8 percent of Americans compost their waste, including residents in cities like San Francisco and Seattle, where composting is part of the general waste pickup.
“In terms of getting products to a commercial composting system in the U.S., there’s only a handful of communities that have collections for those kinds of materials right now,” Christman said.
“There’s no silver bullet,” Bob Lilienfeld, editor of the Use Less Stuff Report (ULS) tells Earth911. “There isn’t a single product that solves every issue out there.”
Since PLA is not recyclable in our current system, these bottles can end up getting thrown out. Lilienfeld notes that in order for anything to break down, including biopolymers, light, water and heat are required – exactly elements that “landfills are designed to keep out,” so they won’t break down as they are designed.
Overall LCA Impacts
The cumulative effect of the production of biodegradables and biopolymers are important as well.
According to Lilienfeld, in terms of solid waste, energy consumption and GHG emissions, “There’s really no biopolymer that outperforms a nonbiopolymer on those LCA measurements.You have to constantly balance the functionality of the product, the cost of that product and then finally the perceptions of that product [with its overall lifecycle impact].”
On the other hand, Bopp notes that “PLA has the lowest carbon footprint and the lowest use of fossil fuel energy of all the commercial plastics,” through the process of pelletizing the plastic – the step before the plastic is molded into an actual product.
“While these are important areas of innovation, [the use of PLA] needs to be teamed with products that are most suited to their applications […] and looking at their full lifecycle inventories,” said Christman.
“The other part that’s important there is the use of lifecycle inventories to make sure they [PLA plastics] do reduce environmental impact or not,” he adds. “There are cases where you can put more energy into making a renewable material into a package than you can save.”
What Really Matters
No matter which side of the fence you’re on, the most important considerations with these materials is to understand what they are and how you can (or can’t) use them in your area.
“The overall theme is that [bio-based materials and biodegradables] are innovative, but we need to be careful about it and we need to do some careful analysis,” said Christman.
Lilienfeld agrees. “Ultimately, like it or not, it’s all about the numbers. It’s not about making people feel good. Sometimes, natural gas may be the better source. On the other hand, if something grown domestically reduces our need for foreign oil and our need to defend ourselves, then that’s an important consideration too,” he says.
“Nature doesn’t care if you feel good about what you do. If what you do actually increases GHG gases […] it’s ultimately a negative.”
If you use bio-based materials that can be recycled in today’s current stream, such as Coke’s new Plant Bottle or Dow’s sugar cane-based resins, then the answer is simple: Toss it in the recycling bin. But if you do buy compostable plastics, be sure to seek out an industrial composting facility near you.
Earth911 partners with many industries, manufacturers and organizations to support its Recycling Directory, the largest in the nation, which is provided to consumers at no cost. The American Chemistry Council is one of these partners.