What you need to know about plant-based plastics
Can bioplastics truly relieve pressure on the environment? Experts weigh in.
More than eighteen trillion pounds of plastic have been produced to date, and eighteen billion pounds of plastic flows into the ocean every year. It ensnares the marine animals we cherish and the fish we put on our plates, it appears in the table salt we use, and it’s even found in our own bodies.
As more research on the impact of using so much plastic comes to light, consumers and manufacturers are left scrambling for an alternative to the ubiquitous material, and bioplastics have emerged as a potential alternative.
At a glance, the name sounds promising, with a prefix that hints at an Earth-friendly product. But is bioplastic the panacea for our environmental woes? An easy-to-use single-use item that feels like plastic minus the guilt?
It’s complicated, say scientists, manufacturers, and environmental experts, who warn its potential merits rest on many “ifs.”
What is bioplastic?
Bioplastic simply refers to plastic made from plant or other biological material instead of petroleum. It is also often called bio-based plastic.
It can either be made by extracting sugar from plants like corn and sugarcane to convert into polylactic acids (PLAs), or it can be made from polyhydroxyalkanoates (PHAs) engineered from microorganisms. PLA plastic is commonly used in food packaging, while PHA is often used in medical devices like sutures and cardiovascular patches.
Because PLA often comes from the same large industrial facilities making products like ethanol, it’s the cheapest source of bioplastic. It’s the most common type and is also used in plastic bottles, utensils, and textiles.
Plants, oil, and the fight for food security
“The argument [for bio-based plastics] is the inherent value of reducing the carbon footprint,” says chemical engineer Ramani Narayan from Michigan State University, who researches bioplastic.
About eight percent of the world’s oil is used to make plastic, and proponents of bioplastic often tout a reduction in this use as a major benefit. This argument rests on the idea that if a plastic item does release carbon once it’s discarded, as it degrades, bioplastics will add less carbon to the atmosphere because they’re simply returning the carbon the plants sucked up while growing (instead of releasing carbon that had previously been trapped underground in the form of oil).
A whale shark swims beside a plastic bag in the Gulf of Aden near Yemen. Although whale sharks are the biggest fish in the sea, they're still threatened by ingesting small bits of plastic.
However, that’s not the end of the story. One 2011 study from the University of Pittsburgh found other environmental issues associated with growing plants for bioplastic. Among them: pollution from fertilizers and land diverted from food production.
Using a substance like corn for plastic instead of food is at the center of a debate over how resources should be allocated in an increasingly food-scarce world.
“The other value proposition is that plant biomass is renewable,” Narayan adds. “It's grown all over the world. Oil is concentrated in regions. Bioplastics support a rural, agrarian economy.”
Bio-based plastics have benefits, but only when taking a host of factors into consideration, says environmental engineer and National Geographic explorer Jenna Jambeck, who is also at the University of Georgia.
“Where is it grown? How much land does it take up? How much water is needed?” she gives as examples of important questions.
Whether bio-based plastics are ultimately better for the environment than oil-derived ones “is a big question based on many 'ifs,'” she says. In other words, there’s no clear answer at present.
What happens when we're done with it?
Depending on the type of polymer used to make it, discarded bioplastic must either be sent to a landfill, recycled like many (but not all) petroleum-based plastics, or sent to an industrial compost site.
Industrial composting is necessary to heat the bioplastic to a high enough temperature that allows microbes to break it down. Without that intense heat, bioplastics won't degrade on their own in a meaningful timeframe, either in landfills or even your home compost heap. If they end up in marine environments, they'll function similarly to petroleum-based plastic, breaking down into micro-sized pieces, lasting for decades, and presenting a danger to marine life.
“If PLA [bioplastic] does leak out, it also will not biodegrade in the ocean,” says Jambeck. “It's really not any different from those industrial polymers. It can be composted in an industrial facility, but if the town doesn't have one, then it's not any different.”
So, should you use it?
One of the largest manufacturers of bioplastic in the U.S. is Colorado’s Eco Products. They buy raw corn-based PLA from NatureWorks, a chemical manufacturer in Blair, Nebraska.
Eco Products deferred questions about their products to the Plastics Industry Assocation (PLASTICS), who said that demand for bioplastics has increased in the past decade or so.
Consumer interest in sustainable alternatives to plastics and more efficient technology are driving that growth, says PLASTICS Assistant Director of Regulatory and Technical Affairs Patrick Krieger.
Addressing criticism that bioplastics may divert land away from growing food, Krieger said companies represented by Plastics partner with groups like the World Wildlife Fund’s Bioplastic Feedstock Alliance to ensure crops are grown sustainably.
But environmentalists still say a serious dearth of industrial compost sites mean bioplastics will do little to curb the amount of plastic entering waterways.
Dune Ives is the executive director of the Lonely Whale, an environmental non-profit geared toward business-oriented solutions, particularly around plastics. In 2017, the group headed a “Strawless in Seattle” campaign to lobby for a plastic straw ban. As part of that effort, Lonely Whale investigated whether they would tout bioplastic straws as an alternative. One of the things they learned: Among local businesses that did have compost bins, few reported bioplastic items actually making it into the appropriate places, says Ives.
“We quickly realized that the idea of compostable plastic sounds very interesting, especially if you look at an area like Seattle, but there's still that human element of you and me,” she says.
Dune adds that without adequate composting infrastructure and consumer know-how, bioplastic products can end up an example of greenwashing, a phrase coined by environmentalists to indicate when consumers are misled about how sustainable a product truly is.
“The marketing is getting us to feel good about what we're buying,” she says, “but the reality is the systems aren't in place to accommodate for those materials.”
The Biodegradable Products Institute (BPI) is a non-profit formed to advocate for biodegradable products and waste infrastructure. They see bioplastics and industrial composting as untapped potential.
“Composting is inherently local,” says Rhodes Yepsen, the executive director of BPI. “It won't make sense to ship food waste to another country. It rots quickly, and it's primarily water. It's heavy and messy.”
He points out that recycling is often inefficient, capturing less than a fifth of recyclable material produced in the world.
“Fifty percent of the waste we generate is biodegradable waste like food and paper,” says Narayan, who also serves as a scientific adviser for BPI. He thinks landfills should be eliminated altogether and replaced by more robust and comprehensive waste collection.
“Landfills are tombs. We are preserving garbage. That makes no sense,” he says.
Ives points to opportunities to create sustainable alternatives that don’t have any plastic.
Plastic made from petroleum or plants like corn is among the cheapest material for things like packaging, but smaller-scale manufacturers are developing even more natural alternatives. In the U.K., one boutique is growing fungus into lightweight furniture, and in the U.S., the Department of Agriculture is using a milk film to create packaging that keeps food fresh.
“This is a field right now for entrepreneurial investors. There’s no shortage of incredible opportunity for alternatives that are marine degradable, that don’t overtax the land and our food production system,” Ives says.
Correction: An earlier version of this story incorrectly stated products manufactured by NatureWorks. This article has also been updated to clarify that PLA is made from plant sugar, not contained in the plant itself.