Growing crops to make plastic could theoretically reduce reliance on fossil fuels and even remove carbon from the atmosphere, but at an enormous environmental cost.
IT’S THE YEAR 2050, and humanity has made massive progress in decarbonizing. That’s largely thanks to the negligible price of solar and wind power, cratering even back in 2022. Yet the fossil fuel industry hasn’t just doubled down on making plastics from oil and gas—instead, as the World Economic Forum warned it would happen, it has tripled production from 2016 levels. In 2050, humans are churning out trillions of pounds of plastic a year and, in the process, emitting the greenhouse gas equivalent of over 600 coal-fired power plants. Three decades from now, we’ve stopped using so much oil and gas as fuel, yet way more of them as plastic.
In 2022, people are trying to head off that nightmare scenario with a much-hyped concept called “bio-based plastics.” The backbones of traditional plastics are chains of carbon derived from fossil fuels. Instead, Bioplastics use carbon extracted from crops like corn or sugarcane, mixed with other chemicals, like plasticizers, found in traditional plastics. Growing those plants pulls carbon out of the atmosphere and locks it inside the bioplastic—if it is used for a permanent purpose, like building materials, rather than single-use cups and bags.
At least, that’s the theory. In reality, bio-based plastics are problematic for a variety of reasons. It would take an astounding amount of land and water to grow enough plants to replace traditional plastics—plus energy is needed to produce and ship it all. Bioplastics can be loaded with the same toxic additives that make plastic plastic and still splinter into micro-sized bits that corrupt the land, sea, and air. And switching to bioplastics could give the industry an excuse to keep producing exponentially more polymers under the guise of “eco-friendliness” when scientists and environmentalists agree that the only way to stop the crisis is just to stop making so much damn plastic, whatever its source of carbon.
But let’s say there was a large-scale shift to bioplastics—what would that mean for future emissions? That’s what a new paper in the journal Nature set out to estimate, finding that bioplastics could go carbon-negative if a slew of variables were to align—and that’s very theoretical.
The modelling considered four scenarios for how plastics production—and the life cycle of those products—might unfold through the year 2100, modelling even further out than those earlier predictions about the production through 2050. The first scenario is a baseline in which business continues as usual. The second adds a tax on CO2 emissions, making it more expensive to produce fossil-fuel plastics, encouraging a shift toward bio-based plastics and reducing emissions through the end of the century. (It would also incentivize using more renewable energy to produce plastic.) The third assumes the development of a more circular economy for plastics, making them more easily reused or recycled, reducing emissions and demand. The last scenario imagines a circular bio-economy in which much more plastic has its roots in plants and is used repeatedly.
“Here, we combine all of these: We have the CO2 price in place, we have circular economy strategies, but additionally, we kind of push more biomass into the sector by giving it a certain subsidy,” says the study’s lead author, Paul Stegmann, who's now at the Netherlands Organization for Applied Scientific Research but did the work while at Utrecht University, in cooperation with PBL Netherlands Environmental Assessment Agency. He says that if all three conditions are met, it is enough to push emissions into the negative.
In this version of the future, people would still have to grow lots of crops to make bioplastics, but those plastics would be used—and reused—many times. “You basically put it into the system and keep it as long as possible,” says Stegmann.
This is a hypothetical scenario, not a prediction, for the plastics industry's future. Many pieces would have to fall together just the right way for it to work. Stegmann and his colleagues note in their paper that “a fully circular plastics sector will be impossible as long as plastic demand keeps growing.”
Plastics companies will happily meet that demand by ramping up production, says Steven Feit, senior attorney at the Center for International Environmental Law, which did the emissions report showing what would happen if plastics manufacturing grew through the year 2050. “The pivot to petrochemicals has been the plan for years for the broader fossil fuel industry,” he says. “It's understood that plastics and nitrogen fertilizers are the two real pillars of petrochemicals, which are the engine of growth for fossil fuels.”
And as long as the plastics industry keeps producing exponentially more of it, there’s no incentive to keep the stuff in circulation. It’s so cheap to manufacture, so recycling doesn’t work in its current form. (Among the many reasons scientists are calling for negotiators of a new treaty to add a cap on production is that it would increase the price and demand for recycled plastic.) Another wrinkle is that plastic can only be recycled once or twice before it becomes too degraded. Some products, like multilayered pouches, have become increasingly complicated to recycle, so wealthy nations have been shipping them all to economically developing countries, which is about as far from a circular economy as possible.
Another issue is the space needed to grow the feedstock crops. “It increases the already huge pressure on land use,” says Jānis Brizga, an environmental economist at the University of Latvia, who studies bio-based plastics but wasn’t involved in the new paper. “Land use change has been one of the main drivers for biodiversity loss—we're just pushing out all the other species.”
In 2020, Brizga published a paper calculating how much land it would take to grow enough plants for bioplastics to replace all the traditional plastics used in packaging. The answer: At a minimum, an area bigger than France requires 60 per cent more water than the European Union’s annual freshwater withdrawal. (The new paper didn’t consider land use or water, but Stegmann says that could be an avenue for future research.)
It would also take many chemicals to keep those plants healthy. “Many of these crops are produced in intensive agricultural systems that use a lot of pesticides and herbicides and synthetic chemicals,” Brizga says. “Most of them are also very dependent on fossil fuels.”
And from a human health perspective, we don’t want to keep plastics circulating us. A growing body of evidence links their component chemicals to health problems: One study linked phthalates (a plasticizer chemical) to 100,000 early deaths each year in the US, and the researchers were conservative with that estimate. Microplastics are showing up in people’s blood, breast milk, lungs, guts, and even newborns’ first faeces because we’re surrounded by plastic products—clothing, carpeting, couches, bottles, and bags.
It’s also unclear what kind of climate effect the plastics will have after they’re produced. Early research on microplastics suggests that they release significant amounts of methane—an extremely potent greenhouse gas—as they break down in the environment. Even if a circular bioplastics economy attempts to keep carbon and methane locked up by turning plastics into long-term building materials or landfilling, whatever can’t be used again, nobody knows if it will work. We need more research on how plastics off-gas their carbon under different conditions.
The more plastic we produce, the more corrupted the environment grows—it’s already poisoning organisms and destabilizing ecosystems. “I fear that by the time we get enough answers to all of our questions, it will be too late,” says Kim Warner, senior scientist at the advocacy group Oceana, who wasn’t involved in the new paper. “The train will have already left the station for what it's doing to the atmosphere and the oceans, carbon and health, and everything else.”
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