Are plastics the new natural gas?

Yiannis Lev­endis, Dis­tin­guished Pro­fessor Mechan­ical and Indus­trial Engi­neering at North­eastern, 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.

Con­sider these sta­tis­tics: In 2011, global plastic pro­duc­tion reached 280 mil­lion tons. The U.S. 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.

“Instead of throwing them away,” Lev­endis won­dered, “could we make use of them in a cleaner way?” The answer, it turned out, was yes.

Burning plastic in the tra­di­tional manner cre­ates extremely pol­luting byprod­ucts, as evi­denced by the black smoke pro­duced by the cup. But this didn’t thwart Lev­endis, who noted that plastic con­tains the same amount of energy per pound as pre­mium fuel.

“We wanted to tackle the problem by pre­pro­cessing the plas­tics,” said Chuanwei Zhuo, a doc­toral can­di­date in Lev­endis’ lab. Toward that end, the team devel­oped a com­bus­tion system that adds a simple step to the burning process that allows for turning plastic into a fuel that burns just as cleanly as nat­ural gas.

Pro­fessor Yiannis Lev­endis and doc­toral can­di­date Chuanwei Zhou with their reactor. Photo by Brooks Canaday.

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 patent-​​pending process gave way to another sur­prising result: when the researchers intro­duced a bit of stain­less steel into the reactor, they found it acted as a cat­a­lyst for growing uni­form carbon nan­otubes. Thus, not only can our plastic waste problem be rerouted to gen­erate elec­tricity, it can also be upcy­cled to gen­erate one of the market’s most pop­ular new materials.

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,” Zhuo said. But this is the first time anyone has burned them so cleanly.

news @ Northeastern

7 Comments on "Are plastics the new natural gas?"

Dave Thompson on Thu, 5th Dec 2013 1:03 am 



Is this a good way to use scientific research? Find more ways to continue our industrialized world.I am starting to lose all hope for humanity.

Kenz300 on Thu, 5th Dec 2013 1:06 am 



The worlds oceans are being polluted with plastics….

Anything that recycles, reuses or reduces the amount of waste plastic that is accumulating in the environment is a good thing.

DC on Thu, 5th Dec 2013 1:16 am 



I am quite skeptical of the anyone claiming thy can burn plastic cleanly. Nor, doeS NG burn ‘cleanly’. Its pollution is just less obvious. Since you can neither create or destroy matter or energy, all you can do is convert it to a different form. All the toxins contained in the plastic MUST be present and will be outgassed when combusted. There is no way around this. All the long chain polymers and dixons contained in the plastic initially, will have to go out the tailpipe in one form or another. I suspect the only thing this process will actually accomplish, is to make all the highly toxic and long lived parts of the plastics, invisible to the naked eye.

It wont make them ‘go away’.

rollin on Thu, 5th Dec 2013 3:54 am 



280 million tons of plastic makes about 900 million tons of CO2 when burned. Almost another gigaton, and when the energy to collect and process all this is added in, a gigaton at least. Just another form of oil.

Wonder where the vanadium goes?

Norm on Thu, 5th Dec 2013 1:58 pm 



Lets have more tire fires. Fun for the whole family.

SteveO on Thu, 5th Dec 2013 3:39 pm 



I agree with DC. All plastics have a highly reactive halogen group element like Chlorine or Florine in them. What is happening to those elements? They have to be in the combustion waste somewhere.

Norm on Thu, 5th Dec 2013 8:56 pm 



If the elements are in the ash, why is that bad? Fire ash, by definition is elements and molecules. Kinda lime moon dust. Dump with the coal ash. Solved.