Environment

Heat and carbon turn plastic waste into jet fuel

Heat and carbon turn plastic w...
Hanwu Lei and his team at WSU
Hanwu Lei and his team at WSU
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Hanwu Lei and his team at WSU
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Hanwu Lei and his team at WSU

Commonly used to make a wide variety of items, low-density polyethylene can be recycled into new plastic, but there's much more waste than recycling facilities can currently handle. With that in mind, scientists have now devised a method of converting the material into something else – jet fuel.

Led by Assoc. Prof. Hanwu Lei, a team at Washington State University started with low-density polyethylene waste obtained from sources such as plastic bags, milk cartons and water bottles. They then ground that plastic into granules measuring approximately 3 mm across, or approximately the size of a grain of rice.

Those granules were then placed inside of what's known as a tube reactor, on top of a bed of activated carbon. The plastic and carbon were subsequently heated to a range of 430 to 571 ºC (806 to 1,060 ºF), resulting in a thermal decomposition process called pyrolysis. With the carbon acting as a catalyst, this caused the plastic to break down and release its stored hydrogen content.

After testing seven different types of activated carbon, the team was ultimately able to obtain a mix of 85 percent jet fuel and 15 percent diesel fuel from the plastic. Those fuels can be separated from one another, plus the carbon can also be separated for subsequent reuse, and can be reactivated once it starts losing its catalytic effect.

Overall, it's claimed to be a very efficient process, and it could reportedly be scaled up to industrial levels with little problem.

"We can recover almost 100 percent of the energy from the plastic we tested," says Lei. "The fuel is very good quality, and the byproduct gasses produced are high quality and useful as well."

A paper on the research was recently published in the journal Applied Energy. British Airways may be interested in the findings, as the airline has announced plans for a facility that would convert garbage – such as plastic waste – into jet fuel.

Source: Washington State University via EurekAlert

13 comments
Skipjack
How efficient? Does it take more energy to make the fuel than you get from burning it? If so, it is worthless.
WolfeSA
This is excellent. The problem with recycling is value addition. At the moment the game add from selling it for reuse as a bottle is low. But it's it was a feedstock for jet fuel then you can charge more. It's worth subsiding because the positive impact on society is high. All you need is you get to a compact stage where such plants can be placed next to landfills. But if we ban single use plastics this tech may need a wider range of plastic inputs.
Nik
Should I buy a landfill site full of plastic? It might be an oil-well waiting to happen!
roger90
Cost per gallon? Remember the biofuels at $22 per gallon?
myale
Waste pyrolysis has been around for ages - https://wastepyrolysisplant.net/waste-plastic-to-fuel - the article needs more information as to what makes this version better
McDesign
From the original article, "You have to separate the resulting product to get jet fuel," Lei said. "If you don't separate it, then it's all diesel fuel." Uh - this is at best a vague statement of the end of the process - would like to see actual detail.
Expanded Viewpoint
I've read a few articles about bio-fuels, but not even one of them ever mentioned a price point or any efficiency levels. Which ALWAYS leads me to wonder why they are doing it, if it's not cost effective. Talk about a dollar waiting on a dime! $22 for a gallon of bio-fuel?? That cost really needs to be brought down for anyone to take it seriously. Randy
flyerfly
If one uses solar generated heat this might work...if you have to use other sources of heat it seems like a dog chases tail problem. It would be a way of "storing" the solar heat in a long term fashion while getting rid of waste plastic. If it works well the EPA will probably ban its use though...
Username
If milk cartons are made of plastic should we still be calling then cartons? (carton being the french word for cardboard)
DaveWesely
Yeah, just what we need to do - convert more solid carbon compounds into CO2, with engines that utilize less than 33% of the chemical energy in the fuel.