Turning carbon emissions into plastic

By Zoe Cormier

Not only would this reduce the amount of fossil fuels we use, it would have an impact on climate change, lowering greenhouse gas emissions.

Plastic has gotten a lot of bad press lately – and deservedly so. Our careless use of it has covered the earth and filled the oceans with an estimated eight trillions of tons of plastic garbage.

But the dark side of plastic waste can overshadow its importance: without question, plastic revolutionised life in the 20th century. Durable, pliable, sterile and versatile, nothing like plastic polymers can be found in nature. Without it we could never have created vinyl records, magnetic tape, photographic film or compact discs. Without plastic, recorded music and movies would not be possible. Modern medicine is completely reliant on plastic – think blood bags, syringes, and flexible tubing. Auto parts, lightweight aircraft materials, satellites and space shuttles – all reliant on plastic – have allowed us to travel the globe and explore the universe. And of course: computers, phones, and all forms of internet technology. Almost every single person reading these words is doing so because of plastic. Look around you and you will realise how much your daily life is only made possible with plastic.

Aside from the problem of disposal, there’s another nasty side to plastic: the source. It’s easy to forget that plastics are made from fossil fuels. About four per cent of the oil and gas we use annually goes into polymer production – which might not sound like a lot, but it still involves plastic production being wedded to fossil fuel extraction and climate change.

Bioplastics – are they as good as they sound?

Are there alternatives? There has been a phenomenal amount of hype over bioplastics, such as polylactide (PLA): disposable cutlery made from potatoes, bottles fashioned from corn, rubbish bags cleverly crafted from food waste. Sporting cheerful green leaf logos, these seem like an ideal solution, but the truth is far from simple. For one, bioplastics do not biodegrade as easily as the name might suggest, usually requiring industrial composters to process. Even worse, when you factor in the energy required to produce them – harvesting of crops with machinery, processing of raw materials in factories and so on – bioplastics often have a higher carbon footprint than conventional plastics.

plastic plate
In some cases, bioplastics can have a higher carbon footprint than regular plastics. © Claudio Rampinini | Getty
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Researchers at the University of Sheffield recently examined the full environmental impact of producing plastic bottles from a range of materials, including corn and recyclable PET, and bioplastics did not come out well.

Thanks to fertiliser costs, transport, and harvesting, bio-based plastics came out worst. The best performer in the study - virgin fossil oil, says Dr Peter Styring, Professor of Chemical Engineering and Chemistry at the University of Sheffield. Not the result the researchers were hoping for.

Moreover, the water and fertilisers involved can contribute to the pollution of rivers and estuaries through eutrophication. Plus, if people accidentally put bioplastic into their household recycling, the materials can contaminate recycling streams and degrade the quality of recycled plastic.

So far, so disappointing.

There is one alternative chemists have been chasing for over a decade, and we are on the verge of seeing the hard work of thousands of researchers bear fruit: plastics made from carbon dioxide.

Instead of using fossil fuel as the feedstock [raw material], you can turn the industry on its head by using waste carbon dioxide by using chemical tricks – this will revolutionise the petrochemical sector."

Prof StyringDirector of the UK Centre for Carbon Dioxide Utilization

Plastic from CO2

“Instead of using fossil fuel as the feedstock [raw material], you can turn the industry on its head by using waste carbon dioxide by using chemical tricks – this will revolutionise the petrochemical sector,” says Prof Styring, who is also the Director of the UK Centre for Carbon Dioxide Utilization, has been working on this solution for over a dozen years. Currently most of the carbon dioxide is from hydrogen production, but researchers are working towards capturing industrial emissions as well.

Not only would this reduce the amount of fossil fuels we use, it would have an impact on climate change, lowering greenhouse gas emissions.

At the CDUUK, researchers have figured out how to make polyacrylamide from carbon dioxide, for example. “It’s genuinely crazy to think you can make Nylon from carbon dioxide, but we’ve done it,” says Prof Styring.

The key to making plastic out of carbon dioxide lies in designing sophisticated catalysts – materials that speed up the rate of a chemical reaction without being used up in the process - such as compounds containing metals like copper.

Scientists at Covestro discovered a catalysts that could allow carbon dioxide to react with epoxides to produce a family of chemicals called “polyether polycarbonate polyols” the basis of the polyurethane – the material found in mattresses, cushions, and refrigerator insulation.

ball in a net
One day our plastic could come from the air. © Yasuhide Fumoto | Getty

Sleeping on gas

Covestro plants in Germany are producing mattresses formed of 20 per cent carbon dioxide under the brand name Cardyon. Given that more than 15 million tonnes of polyurethane are made globally every year, switching to carbon dioxide as a feedstock could have a huge impact.

In the UK, Econic is also producing polyurethane from carbon dioxide, and expect to have foam products on the shelves within two years, as well as coatings, sealants, and elastomer.

Not only do these materials match conventional plastics in quality, they can even exceed them in some ways. “We are discovering that some of our materials have enhanced performance, such as flame retardant capacity or scratch resistance,” says Leigh Taylor, Head of Sales and Licensing for Econic.

Econic estimate that if 30 per cent of all polyols (molecules used as cross linking agents) were made from carbon dioxide, this would result in a savings of 90 million tonnes of carbon dioxide from the atmosphere – equivalent to four million trees, or taking two million cars off the road. What’s more, because carbon dioxide is so cheap – about $100 a tonne, compared to $2,000 for propylene oxide (the standard raw material) – it would save a manufacturer $10 million a year for a plant with a 50 kilotonne annual output.

An even more ambitious goal is to produce ethylene from carbon dioxide: about half the plastic we produce globally is created with ethylene, making it one of the most important raw materials in the world. At Swansea University, Professor Enrico Andreoli of the Energy Safety Research Institute and his team are working to develop copper-containing catalysts that allow for the creation of ethylene by combining carbon dioxide with water and electricity.

It will take maybe 20 years to produce the plastic polyethylene on a commercially viable scale from ethylene made from carbon dioxide. “But we won’t be able to make ethylene from fossil fuels in 30 or 40 years – so already we have a need to pursue other ways to make it from carbon dioxide,” says Prof Andreoli, just to put that in perspective.

At the University of Bath, chemists under Prof Antoine Buchard at the Centre for Sustainable Chemical Technologies have developed a way to make polycarbonate (used for reusable containers such as baby bottles) by combining carbon dioxide with sugars such as xylose, the main component in wood easily derived from used coffee grinds.

Current manufacturing processes for polycarbonate typically use phosgene (a toxic gas used as a chemical weapon in WWI) and a chemical called bisphenol-A, which mimics estrogen and is now banned from baby products in countries such as Canada. The sugar-based polycarbonate would be safer to produce and safer to use, making it suitable for medical implants, stitches and organ scaffolds.

In the US, chemists at Rutgers University have developed a new technique using electrocatalysts containing nickel and phosphorus to combine water and carbon dioxide with electricity to produce complex carbon-containing molecules that can be used to produce plastics and other products such as pharmaceuticals. “This is essentially artificial photosynthesis,” says Professor Charles Dismukes, Distinguished Professor in the Department of Chemistry and Chemical Biology at Rutgers University–New Brunswick. “We knew it was possible to beat natural photosynthesis for efficiency – and this is just blowing it away.”

Conventional ways to produce plastics might be the norm – but that doesn’t make them ideal, says Prof Dismukes.

“Creating monomer building blocks from fossil fuels is a very energy intensive and dirty process: using heat to drive the chemical reaction is slow, and incredibly wasteful and inefficient,” he says. “We don’t need to do it that way.”

Featured image by George Clerk | Getty