Everything you need to know about plant-based plastics

In partnership with the National Geographic Society.

More than eight trillion kilograms of plastic have been produced to date, and eight billion kilograms of plastic flow 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?

The answer?

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 from polylactic acids (PLAs) found in plants like corn and sugarcane, 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).

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 fertilisers and land diverted from food production.

Using a substance like corn for plastic instead of food is at the centre 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, that also makes livestock feed, sweeteners, and ethanol.

Eco Products deferred questions about their products to the industry trade association 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 representative Elleni Almandrez.

Addressing criticism that bioplastics may divert land away from growing food, Almandrez 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. Earlier this year, 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 realised 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.

Now read 5 Recycling Myths Busted.

National Geographic is committed to reducing plastics pollution. Learn more about our non-profit activities at natgeo.org/plastics. This story is part of Planet or Plastic?—our multiyear effort to raise awareness about the global plastic waste crisis. Learn what you can do to reduce your own single-use plastics, and take your pledge.