2011 saw the global plastic production reaching 280 million tons. The U.S. itself swept aside 32 million tons as waste, and just 8 percent of that waste was recovered for recycling. The rest found its way into landfills and some into the oceans, accounting for countless seabird and marine mammal deaths. Burning plastic in the traditional manner creates extremely polluting byproducts. But this didn’t thwart Yiannis Levendis, the Distinguished Professor Mechanical and Industrial Engineering at Northeastern University who noted that plastic contains the same amount of energy per pound as premium fuel.
Yiannis Levendis keeps a photograph of a burning plastic foam cup tacked to the wall above his desk. Thick black smoke emanates from the receptacle, which, subsequent pictures reveal, was reduced to a sooty powder by the end of the combustion process. The photo represents a mission for Levendis, whose expertise in combustion and device design has led to the development of dozens of clean energy products. Levendis wondered, “Instead of throwing them away, could we make use of them in a cleaner way?” The answer, it turned out, was yes.
That simple step has a daunting name: pyrolytic gasification. Instead of directly setting the cup aflame with a match in the open air, the team’s reactor heats the material to a whopping 800 degrees Celsius in a completely oxygen-free environment. This causes the plastic to become a gas, which is then mixed with air before it is burned as a clean fuel. The researchers have also shown that the same process works for burning biomass, a leading alternative fuel source that is rapidly gaining traction as our global energy demand reaches new heights. Using plastic as fuel is not a new idea but this is the first time anyone has burned them so cleanly.
Harminder Singh