Cars fueled by plastic waste: Scientists develop novel recycling solution

04 Sep 2018 --- Scientists at Swansea University, UK, may have found a way to minimize the scourge of plastic pollution while feeding the insatiable and global demand for car fuel. Discarded plastic could be used to fuel cars in the future thanks to a ground-breaking process developed by scientists from the University. The team believes this process could be cheaper than recycling because any kind of plastic can be used and it does not need to be cleaned first. The process has been able to transform unwanted plastic into hydrogen which in turn could be used to run vehicles.

“We have been working in the field of solar-driven fuel production for a few years, and this built-up expertise allowed us to develop a catalyst that can generate hydrogen from plastics,” Dr Moritz Kuehnel of the University's Chemistry Department tells PackagingInsights.

“We have previously shown that we can generate hydrogen from other types of waste (waste biomass, paper, cellulose), so it didn't come as a total surprise that we could translate this approach to plastics.”

He adds: “What did surprise us, though, is the fact that we see the same hydrogen production whether we use highly pure plastic samples from a chemical supplier or a real piece of plastic cut out of a water bottle. Conventional recycling requires very 'clean' waste, free of any dirt or other types of plastics. Our solar-driven process is very tolerant to contaminants and real-world waste.”

Kuehnel explains how light-absorbing material is added to the plastic before it is placed in an alkaline solution and then exposed to sunlight, which creates hydrogen.

“There's a lot of plastic used every year – billions of tons – and only a fraction of it is being recycled. We are trying to find a use for what is not being recycled,” he says.

Most plastic bottles are made from PET [polyethylene terephthalate] which can be recycled but often end up being burned or thrown into landfill.

Kuehnel continues: “But even if you do recycle it, it needs to be very pure – so only PET, nothing else mixed in with it ... and it has to be clean, no grease, no oil.”

“Potentially you need to wash it which is very expensive, and even if you do all of that, the plastic you get isn't always as nice as virgin material.”

“The beauty of this process is that it's not very picky. It can degrade all sorts of waste.”

“Even if there is food or a bit of grease from a margarine tub, it doesn't stop the reaction, it makes it better.”

“The process produces hydrogen gas. You can see bubbles coming off the surface. You can use it, for example, to fuel a hydrogen car."

However, he warned that rolling out the project on an industrial level may still be years away.

“Our work currently is at the proof-of-concept stage, meaning we can generate only very small amounts of hydrogen. The next step will be scale-up, which is currently ongoing,” he tells PackagingInsights.

“One obstacle is that the photocatalyst that we use for the hydrogen production is toxic, and we are working on developing a more benign material with the same performance. The Austrian company OMV, which are part-funding this work are supporting our scale-up activities,” he says.

In other recent research, a team of researchers has found that polyethylene releases methane and ethylene into the environment when exposed to sunlight. Dr. Sarah-Jeanne Royer of the University of Hawaii intended to measure methane gas coming from biological activity in seawater but instead found that plastic bottles were a greater source of the warming molecule than the bacteria in the water.

Under the conditions of Kuehnel’s studies, hydrogen was the only gas detected. This is in addition to the formation of organic compounds which were also observed, for example terephthalic acid, which can be collected and used to make new plastics.

By Joshua Poole, with additional reporting from Laxmi Haigh