Researchers at the University of Illinois have developed a method for converting waste polystyrene into a sustainable jet fuel additive, overcoming a key obstacle to the wider use of sustainable aviation fuels.
The study, undertaken by lead scientist Hong Lu and his colleagues at the Illinois Sustainable Technology Centre, addresses the challenge to switch commercial aircraft in the United States from their near-total reliance on fossil fuels to more sustainable aviation fuels.
The study details a cost-effective method for producing ethylbenzene, an additive that improves the functional characteristics of sustainable aviation fuels, from polystyrene, a hard plastic used in many consumer goods.
Lu and his colleagues chose to develop ethylbenzene because it has a lower tendency to form soot upon burning than other highly aromatic compounds. They chose to start with polystyrene because it is rich in hydrocarbons and is abundantly available in the waste stream.
“We produce in the U.S. about 2.5 million metric tons of polystyrene every year, and almost all of it is disposed of in landfills,” Lu said.
Several government agencies in the US have created a roadmap for addressing the climate-related impacts of fossil-fuel-derived aviation fuels.
The Sustainable Aviation Fuel Grand Challenge sets goals to produce three billion gallons per year of domestic sustainable aviation fuels by 2030, and 100 per cent of projected aviation jet fuel use, or 35 billion gallons per year, by 2050.
At present, standards require a minimum of 8.4 per cent aromatic hydrocarbons be included in any blend of sustainable aviation fuels and fossil-derived fuels “to maintain compatibility with existing aircraft and related infrastructure,” the researchers report.
“Currently, they use a blend of 20 per cent to 30 per cent sustainable aviation fuels and 70 per cent to 80 per cent conventional jet fuel,” said Lu.
When mixed with a sustainable aviation fuel, the polystyrene-derived ethylbenzene performed “almost as well as ethylbenzene derived from fossil fuels,” Lu said. Further purification would improve its performance.
When undertaking a preliminary cost analysis, Lu said the team found that the ethylbenzene produced from waste polystyrene is cheaper than that produced from crude oil.
“A lifecycle analysis of our ethylbenzene found it reduced carbon emissions by 50 per cent to 60 per cent compared with the ethylbenzene made from crude oil.”
The findings are reported in the journal ACS Sustainable Chemistry and Engineering.
For more information, visit: https://pubs.acs.org
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