Turing plastic waste into green energy

Environmental experts in Newcastle are working on a pioneering scheme to turn plastic waste into renewable energy aiming at current plastic pollution issues. According to the statistics, today 31% of plastic waste ends up in landfills, and about 8 million tons of plastic waste escapes into the oceans every year, which has a devastating impact on ecosystems and oceans.

Many countries have put forward ambitious targets to reduce plastic waste and recycle more. The UK aims to recycle 50% of all household waste by 2020. However, plastic often contains additives which make them stronger and more durable. Many of those additives could extend the life of products if they become litter. Some of them may take 400 years to break down.

Copyright-free images on Unsplash.com. Image source: https://unsplash.com/s/photos/plastic-pollution

But a recent study may provide a new solution – a method to reduce plastic waste and generate green energy at the same time.

Dr Anh Phan, the senior lecturer in chemical engineering at Newcastle University, is currently leading a pioneering research project to convert waste plastic into green energy and useful chemicals and materials through a process known as cold plasma pyrolysis.

Initial motivation

Anh started to reserach this issue is in 2004 during her PhD when she looked into energy recovery from the waste left behind after recycling . She found that plastic made up about 13% of municipal waste streams. Anh said:

“For me, plastic is valuable. My way is always to look at plastic as a resource but not a waste. I think plastic waste is not a problem, the way we dealing with it is a problem.”

In 2013, after she came to Newcastle University, she was determined to continue her research on plastic recycling issues.

Cold plasma pyrolysis – The new approach

Pyrolysis is a method of heating, which could decompose organic materials at temperatures between 400C and 650C, in an environment with limited oxygen. The process is normally used to generate heat, electricity or fuels, but when cold plasma is added to the equation it can convert waste plastics into hydrogen, methane and ethylene.

Provided by Anh Phan. Image source: https://www.ncl.ac.uk/who-we-are/vision/green-energy/

Hydrogen and methane are commonly known for their potential as alternative clean fuels since they only produce minimal amounts of harmful compounds. And ethylene is the basic foundation of most plastics globally. This means that recovering more ethylene will allow the reuse and reproduction of plastic products in industry.

What’s more, recently, Anh and her teams tested the effectiveness of cold plasma pyrolysis using plastic bags, milk and bleach bottles collected by a local recycling facility in Newcastle. They found that 55 times more ethylene can be recovered from the most widely used plastic (such as HDPE which is frequently used for producing milk cartons, garbage bins and cutting boards) with cold plasma, and 24% of the plastic used in the experiment was converted from HDPE into valuable products (such as laundry detergent).

Further steps

With her research, Anh hopes the cold plasma pyrolysis could help to effectively turn the plastic waste into green energy and useful chemical materials, which could develop a circular, low-carbon economy. Rather than simply recycling the waste plastic, her finding provides a more viable long-term solution to dealing with plastic pollution issues.

Anh hopes this technology could be widely used in industry in the near future.

“We are still doing researche and experiments trying to understand what’s happening. A huge gap still exists in terms of bringing the technology into the industry or bigger scale. But we try to move it up a little further in order to take the technology out.”

Interview/Writing: Jialu Yin
Video edit: Jiaxin Qian

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