The world is drowning in plastic. Each year, over 300 million tons of plastic finds its way to a landfill or into the environment where it will take hundreds of years to decompose and kill all manner of wildlife in the meantime.
A team of chemists at Purdue may have found a partial solution to our plastic woes. As detailed in a paper published this week in Sustainable Chemistry and Engineering, the chemists discovered a way to convert polypropylene—a type of plastic commonly used in toys, medical devices, and product packaging like potato chip bags—into gasoline and diesel-like fuel. The researchers said that this fuel is pure enough to be used as blendstock, a main component of fuel used in motorized vehicles.
Polypropylene waste accounts for just under a quarter of the estimated 5 billion tons of plastic that have amassed in the world’s landfills in the last 50 years.
To turn polypropylene into fuel, the researchers used supercritical water, a phase of water that demonstrates characteristics of both a liquid and a gas depending on the pressure and temperature conditions. Purdue chemist Linda Wang and her colleagues heated water to between 716 and 932 degrees Fahrenheit at pressures approximately 2300 times greater than the atmospheric pressure at sea level.
When purified polypropylene waste was added to the supercritical water, it was converted into oil within in a few hours, depending on the temperature. At around 850 degrees Fahrenheit, the conversion time was lowered to under an hour.
The byproducts of this process include gasoline and diesel-like oils. According to the researchers, their conversion process could be used to convert roughly 90 percent of the world’s polypropylene waste each year into fuel.
“Plastic waste disposal, whether recycled or thrown away, does not mean the end of the story,” Wang said. “Plastics degrade slowly and release toxic microplastics and chemicals into the land and the water. This is a catastrophe because once these pollutants are in the oceans, they are impossible to retrieve completely.”
The obvious benefit of this new conversion process is cleaning up the environment by finding a use for plastic waste. But as Wang pointed out in a statement, the fact that the produced fuel can be sold for a profit will also encourage the recycling industry to rapidly adopt it.
Indeed, as Wang pointed out, time is of the essence when it comes to implementing effective recycling strategies. Every year that nothing is done, millions of tons of plastic flow into the oceans, where they are swallowed by wildlife and kill coral reefs. This plastic is notoriously hard to clean up and poses a mounting threat to entire ocean ecosystems, which can lead to cascading environmental crises across the globe.
It’s unclear how difficult it will be to implement this new plastic conversion process at scale, but at least for once it looks like there might actually be a “great future in plastics.”