Chemists develop a revolutionary technique to convert plastic waste into fuel

Researchers have made a breakthrough in the fight against plastic waste. Chemists from Purdue University in the United States (US) have developed a ground-breaking technique to convert plastic waste, namely polypropylene (PP) into pure fuel and other valuable products. This innovation may help to radically reduce the billions of tons of plastic waste that have accumulated in landfills and in the natural environment across the world. According to the researchers, their revolutionary technique could be used to convert about 90 percent of the world’s yearly polypropylene waste into fuel.

Converting plastic waste into valuable products

As explained in their study published in “Sustainable Chemistry and Engineering”, the researchers have transformed PP waste into oil using supercritical water at 425 °C. Polypropylene waste accounts for about 25% of the estimated 5 billion tons of plastic that have accumulated in landfills around the world in the past 50 years. It is commonly used in the manufacturing of toys, medical devices and product packing such as potato chip bags.

According to the chemists, this innovative conversion process is net-energy positive and potentially even has higher energy efficiency and lower greenhouse gas emissions than mechanical recycling and incineration. They concluded that the oil derived from PP could be used as gasoline blendstocks (a principal component of fuel used in motorized vehicles) or feedstocks for other chemicals.

Linda Wang, leader of the research team, highlighted in a press communiqué that PP can be transformed into a wide range of valuable products such as clean fuels, polymers and naphta. This innovative technology could bring huge benefits to the recycling industry and drastically reduce the amount of plastic waste that has accumulated around the world. Every year, more than 300 million tons of plastic end up in landfills or into our environment, taking hundreds of years to decompose and releasing toxic microplastics and chemicals into water and soil. And once these pollutants get into oceans, it is practically impossible to retrieve them all back.

Plastic to fuel projects have gained traction since some years already in the energy industry in parallel with the increasing awareness of the environmental damage caused by single-use plastics and poor recycling habits and measures. Researchers from Swansea University have invented a technique to convert plastic waste into hydrogen fuel that could be used to power cars. Dr Moritz Kuehnel explained that this process is not very picky as it can degrade various types of waste. It is also cheaper than actual recycling options, according to the team. Another team from the Chemistry department at the University of California has invented, on its side, a method to transform plastic into diesel by dissolving bonds of polyethylene. The team was successful in deriving a liquid fuel that can be used in cars or for other industrial purposes.

This conversion can give a boost to the recycling industry

The new technique should give a boost to the recycling industry. The latter may be keen to use it as produced fuel could be sold for profit. And this plastic conversion may unlock a positive future for this material notoriously hard to clean up and for the environment. As a matter of fact, even if plastic recycling is becoming an increasingly important sector, it is not a success story. According to statistics, every year over 400 million tons of plastic waste is produced globally. However, only about 9 percent is recycled and some 13 million tons of this waste ends up in oceans.

As Erik Solheim, Head of UN Environment said, “plastic isn’t the problem. It’s what we do with it”. A group of academics covering multiple disciplines across Heriot –Watt University has equally highlighted that the best approach would be to move towards a circular economy for plastics instead of continuing with the current model of ‘make-use-dispose’. They see total bans as short-term goals that do match the reality. Professor David Bucknall from the group of academics argues that there is no clear alternatives for plastics and outright bans may have serious impacts on various spheres. For instance, replacing plastics with currently available materials such as glass or metals would double global energy consumption and triple greenhouse gas emissions.

Creating a circular economy for plastics

Apart from the industrial impact, total bans can have massive societal impacts, as underlines Professor Kate Sang. Today, many people suffering from disabilities rely on various single-use plastics for their everyday lives. She highlights that we have to acknowledge that single-use plastics have revolutionized healthcare and have even become vital for delivering responsible and safe health service. Single-use straws, for example, are essential for many elderly people as well. Paper straws are generally not suitable as they are not flexible and disintegrate rapidly. Silicone straws, on the other hand, have to be sterilized which is not practical in public places. “The idea of straws on prescription is stigmatizing and impractical- imagine getting a GPs appointment for straws!”, argues Kate Sang.

At the same time, she claims that banning plastic food packaging is not the right solution for the time being. In her opinion, ready meals and pre-prepared vegetables or food are a big help to many people who have a hectic timetable and struggle to prepare meals. She advises that manufacturers should be onboarded to develop suitable alternatives and proper collection and disposal of single-use plastics so that neither disabled people nor those who rely on ready meals or pre-prepared vegetables and food are marginalized.

In a bid to create this circular economy for plastics, several countries are coming up with new propositions to encourage recycling. The UK, for instance, will be introducing a new tax on manufacture and import of plastic packaging made up of less than 30 percent recycled material. This new measure should be enforced as from 2022. On a parallel note, much development is being done with regards to alternative materials. Danish company Arla, for example, has already introduced wood-based bioplastic cartons for milk. These cartons can be recycled just like cardboard.