The technical people, those with PhDs in polymer science who have also spent years in application development work, will tell you it is simply impossible to find other materials that perform as well as linear low density polyethylene (LLDPE).
Multilayer LLDPE films are vital in applications such as wrapping food, they argue, thanks to excellent barrier properties. We are told this makes replacing these films impossible, as the end-result would be more food going to waste. It can be argued this makes getting rid of LLDPE morally indefensible in a world where hundreds of millions of people still lack adequate nutrition.
Methane emissions from rotting food are the world’s third largest source of these emissions. You can therefore make a strong case that plastic waste caused by LLDPE is a small price to pay for the benefits it is already delivering in mitigating climate change.
But this is assuming materials science remains static. What if other materials are developed – made from polymers or non-plastic materials – that perform just as well as LLDPE? The public and legislative reaction to the plastic waste crisis is sufficient to make this happen.
New and very ambitious initiatives for dealing with plastic waste are constantly being announced. Take, for example, the 2018 announcement by the Ellen MacArthur Foundation in collaboration with the United Nations Environment Programme to accelerate the shift towards a circular economy. 250 companies, including polymer producers Borealis and Indorama, have signed on to a bold set of sustainability targets for 2025.
This means there is an awful lot of money to be made by innovators if they take on and beat an LLDPE industry that rests on its laurels. Because of the strength of the public backlash against plastic waste, wholesalers, retailers and the public may be willing to accept inferior performance by replacement materials.
Think of the emotional response to pictures of a dead pilot whale in Thailand that was found to have 8kg of plastic in its stomach. People could be willing to pay more for inferior packaging if it is 100% recyclable.
The LLDPE industry must innovate very quickly if it is to avoid a trajectory of low or declining growth. Global demand growth could be lower than our base case prediction of an average of 4.6%/year from now until 2030. If growth were to, say, average just 1%/year, this would result in 118m tonnes of lost demand in 2018-2030 versus our base case, as seen on the first chart.
LLDPE would in this downside scenario end up like polystyrene – it would become an “ex growth” polymer where new investment is hard to justify.
LLDPE confronts loss of demand because, as science stands now, it is very hard to recycle. Plus, around 55% of LLDPE consumption is for single-use applications. This is not the case with HDPE, where recycling is already pretty viable. LLDPE producers have to find ways of economic and sustainable recycling if they are to avoid a major loss of sales.
The loss of 118m tonnes of LLDPE demand would have a major impact on the viability of the whole steam cracker business, unless alternative uses could be found for the lost ethylene demand.
The second chart assumes no alternative uses are found. Based on new investment plans, global ethylene operating rates fall to just 82% from 2025 onwards. In reality, however, new cracker investments would surely be cancelled.
If mechanical recycling – processing waste plastic directly back into polymers – proves impossible, perhaps the answer might be chemicals recycling. Here plastics are broken back down into fuels, feedstock or even other chemicals. A combination of solutions seems likely. We as yet do not know all or maybe even any of the answers. But we cannot afford to delay our search.