New way to turn plastic waste into jet fuel

Scientists have found a novel way to turn daily plastic waste products like water bottles and plastic bags into jet fuel. Researchers at Washington State University in the US melted plastic waste at high temperature with activated carbon, a processed carbon with increased surface area, to produce jet fuel.

"Waste plastic is a huge problem worldwide. This is a very good, and relatively simple, way to recycle these plastics," said Hanwu Lei, an associate professor at WSU. The research, published in the journal Applied Energy, tested low-density polyethylene and mixed a variety of waste plastic products, like water bottles, milk bottles, and plastic bags, and ground them down to around three millimetres, or about the size of a grain of rice.

The plastic granules were then placed on top of activated carbon in a tube reactor at a high temperature, ranging from 430 degree Celsius to 571 degrees Celsius. The carbon is a catalyst, or a substance that speeds up a chemical reaction without being consumed by the reaction. "Plastic is hard to break down. You have to add a catalyst to help break the chemical bonds. There is a lot of hydrogen in plastics, which is a key component in fuel," Lei said.

Once the carbon catalyst has done its work, it can be separated out and re-used on the next batch of waste plastic conversion. The catalyst can also be regenerated after losing its activity. After testing several different catalysts at different temperatures, the best result they had produced a mixture of 85 per cent jet fuel and 15 per cent diesel fuel.

"We can recover almost 100 per cent of the energy from the plastic we tested," Lei said. "The fuel is very good quality, and the byproduct gasses produced are high quality and useful as well," he said. He also said the method for this process is easily scalable. It could work at a large facility or even on farms, where farmers could turn plastic waste into diesel.