This Ingenious Technique Could Turn Plastic Waste Into Clean Fuel

Scientist Linda Wang demonstrates plastic conversion technique
Linda Wang and a team of Purdue scientists claim they can turn polypropylene waste into clean fuels. Purdue Research Foundation image/Vincent Walter

A society that lives by the plastic fork may very well die by it.

That’s how things are looking, anyway, for a world so steeped in disposable habits that any hope for a solution also increasingly seems destined for the landfill.

Sure, there have been some promising ideas. Remember Boyan Slat, the Dutch inventor who developed a plan for Hoovering up the Great Pacific Garbage Patch? Not long after it was deployed, Slat’s system experienced “material fatigue” — likely the result of being strained by all that trash — and the mission was put on hold.

All the while, the plastic tide rises. Its growth is nothing short of "exponential," according to Linda Wang, a professor of chemical engineering at Purdue University.

“We’ll have more plastic than fish by 2050,” Wang says in the video above, which was posted to YouTube earlier this month by Purdue's College of Engineering.

Yet Wang, along with other researchers at Purdue, may have a solution not only to this plastic menace, but also to the growing need for clean energy.

Her team has developed a chemical conversion system that turns polypropylene waste — a durable, lightweight material that accounts for about a quarter of all plastic waste — into a highly pure form of gasoline.

Publishing their findings in the journal Sustainable Chemistry and Engineering, the scientists claim that instead of making plastic go away, they can break it down and repurpose it — essentially using chemistry to undo what chemistry foisted onto the world when plastic was developed back in 1907.

How it works

The process uses "supercritical" water — heated to around 450 degrees Celsius (842 degrees Fahrenheit), beyond the critical point at which distinct liquid and vapor phases exist — to boil plastic waste into an oil, the researchers explain. It takes a couple hours for the supercritical water to complete the transformation, but the result is an oil that can be used as a high-octane gasoline or diesel fuel. It can also be turned into other products, like pure polymers or feedstock for other chemicals.

The researchers have only made the conversion in a laboratory setting so far, but they suggest ramping up the process to a commercial scale may not be far off.

And considering the 300 million metric tons of plastic seeping into the environment every year, that day can’t come soon enough.

“Plastic waste disposal, whether recycled or thrown away, does not mean the end of the story,” Wang says in a press release. “These 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.”