Carbon is almost unique in its ability to form bonds with itself comparable in strength to those it forms with other atoms. This is the basis for its pre-eminent role as the key building block of life. Hence the name ‘organic’ for any chemical compound involving carbon-carbon (C-C) bonds. Proteins, fats, and sugars are each based on a backbone of C-C bonds, elegantly constructed by nature.

Humans have also developed an impressive array of long-chain molecules, based on C-C bonds. These ‘polymers’ are usually compounded with speciality additives and/or other polymers to form the ‘plastics’ which we see used in products across a host of sectors, including packaging, agriculture, construction, consumer, transport, and industrial manufacturing. The current weight of plastic produced per year currently stands at just under 400m tonnes, a figure expected to double well before 2050.

However, there is a catch – the manufacture of plastics can never be decarbonised. Carbon is the fundamental unit without which long-chain molecules cannot be made. Sadly, waste management practices, especially in single-use packaging, imply that nearly 60% of global polymer waste is simply sent to landfill or otherwise discarded. Disgracefully, a growing pile of plastic rubbish is tipped into rivers or dumped into the oceans. The Ellen MacArthur Foundation suggests the oceans could contain more plastic than fish by weight in 2050. This is simply unsustainable and has rightly catalysed a public outcry for change.

Rushing to outlaw plastics is hardly a credible option. The key enabling factor to permit a sustainable plastic industry will be circularity.

So, what can we do? Rushing to outlaw plastics is hardly a credible option. The world would simply grind to a halt overnight if all plastics were banned, and plastics more broadly will necessarily continue to support economic development. A switch to more sustainable consumption patterns has an important role to play, as does a substitution by other materials in some end markets. However, the key enabling factor to permit a full-scale sustainable plastic industry will be circularity – essentially converting waste plastics into future feedstock for the chemical industry itself.

Mechanical recycling is already in use. In essence, this involves chopping down, melting and re-using the plastic waste to create a lower grade plastic. However, the collection processes required prior to re-processing are complex and imperfect. While technical and organisational advances can be expected in future, mechanical recycling can never be more than a partial solution to the plastic waste problem.

Thankfully, there is another way to help us out of the mire, so-called ‘chemical recycling’. This process also transforms the problem, plastic waste for disposal, into a valuable input material for manufacturing – without requiring extensive sorting. It breaks down the chemical bonds holding the waste plastic molecules together, recovering nearly all of the starting material. It then creates smaller molecules which can be used to make other new plastics. Chemical recycling is now at the stage of growing research and commercial development, which is the missing link in making plastic recycling practical in many contexts.

There is clearly a carrot for chemical companies to invest in this technology, but there is also a large stick. Currently, carbon demand  from the chemicals industry accounts for roughly 10% of ‘the barrel’, with the lion’s share going to meet fuel demand in the transport sector. The foreseeable rapid adoption of EVs means that the shift away from oil-based transport fuels is now irreversible. Less gasoline and diesel means less need for oil exploration and refining, and the economics will not support refining merely to provide feedstock for the chemical industry.

Therefore, chemical companies will be forced to find new sources of feedstock in future, at very large scale. Chemical recycling is the answer to that need, and can be a key factor in making circularity a reality for plastics, in turn allowing them to continue to play a key role in society. Indeed, their new life cycle may serve as a model in a future world circular economy. Both humans and ocean dwellers can look forward to a better future as a result.

Dr Paul Satchell