New Technique Could Turn Plastic Back Into Oil

There is way too much plastic in the world—and we’re making more every day, even as we struggle to find a way to get rid of the old stuff. A new study poses an interesting solution: Melting plastic bags and bottles back into the oil it was originally made from.

The new research, published Wednesday in Science Advances, looks at a technique called pyrolysis, which essentially melts down polyolefin into its original form—aka oil and gas. Polyolefins are a very common type of plastic in everyday items from drinking straws to packaging to thermal underwear to plastic cling wrap. It accounts for two-thirds of the world’s plastic demand. The production of these kinds of plastics has been a huge boon for the oil and gas industry, and is giving fossil fuel producers a glimmer of hope for the future; while plastics only account for 14% of oil demand today, they’re projected to make up half the world’s demand for oil by 2050.

The study details a new type of technique for treating single-use plastics that, researchers say, can break down all sorts of tough-to-recycle plastics—including polyethylene bottles and bags—into liquid petrochemicals. One of the most notable things about the new technique is that it’s able to break down the plastics at lower temperatures than other pyrolysis methods, which helps transform the plastic into denser fuel and uses two to three times less energy.

“Most prior work focuses on pyrolysis that heats the plastic to high temperatures of 400-800 [degrees Celsius],” study author Dionisios Vlachos, a professor of chemical and biomolecular engineering at the University of Delaware, said in an email. “The energy need is super high.”

These high-heat techniques, Vlachos said, break down most of the chemical bonds in the plastic, which makes the final product closely resemble light gases like shale. This new technique, by contrast, can create liquid fuels at the lower heat used—around 437 degrees Fahrenheit (225 degrees Celsius)—producing “nearly ready-to-use fuels for cars, trucks, or airplanes and lubricants,” Vlachos said.

Single-use plastics, like bags, straws, and can rings, which are basically meant to be discarded right after use. This easy-throwaway stuff makes up half of the 300 million tons of plastic produced worldwide each year, so there’s a lot of it to work with. It’s also the bulk of what’s gumming up the environment as bigger pieces break down into smaller microplastics that can pose a threat to humans, animals, and ecosystems alike.

Clearly, though, turning it into fuel is not a panacea for all our environmental woes. It basically doesn’t do anything to curb climate change. Fossil fuels, of course, release emissions when you burn them; using a gallon of oil melted down from a bunch of Tupperware won’t change that.

Still, there’s an urgent need to figure out what to do with all this plastic trash that’s clogging up the planet. It’s polluting waterways and killing wildlife. Our current best method of getting ride of it—simply burning the trash—also releases toxic and planet-heating emissions. Converting plastic back to the stuff it was originally made out of may not be a perfect solution, but it sure is better than nothing (and potentially has an added bonus of creating fewer revenue streams for oil and gas companies as we find ways to reuse the stuff they sold to us in the first place). And the time is now, Vlachos said, to throw energy into researching techniques like these, before our plastic addiction runs away from us.

“We need to take action on the plastics problem and develop technologies and policies to eliminate it from the environment,” Vlachos said. “Research takes 10-plus years before it becomes useful. Investing in this field now is a priority.”