Plastics are polymers – complex chains of molecules that make them mouldable to almost any function. But plasticity comes with a price: it requires energy to build up and break down the molecular chains, making plastics recycling a tough nut to crack.
Despite their complexity, though, since the 1960s, a befuddling acronym-soup of plastics has become part of the very definition of modernity. So much so that the world now produces an extraordinary 350 million metric tons every year – well under 10 percent of which is recycled in any way; and – tragically 8 million tons of which end up in the oceans.
What’s more, as most plastics are still derived from oil and manufactured under extreme heat, they are greenhouse-gas intensive – being responsible for around 3-4 percent of global energy-related CO2 emissions – which isn’t far short of the aviation sector’s carbon footprint. Luckily, though, increased public awareness of the damage our plastic-addition is doing to the planet is forging action and investment at regional, city and company-level and a suite of technologies is being scaled up.
Packaging and policy
Perhaps the area of plastics manufacturing on which consumers are most engaged is packaging (which uses around a third of all plastic polymers produced). For example, a 2019 Ipsos poll of 28 countries showed more than eight in ten people saying that manufacturers should be obliged to reduce packaging waste. A lot of this has translated into political action, with the European Union legislating to ban single-use plastic by the end of 2021 and China unveiling a plan to end the use of many plastic products on the same timeframe.
Ending single use plastic means pursuing one of several possible strategies: 1) changing cultural habits by – for example – popularizing reusable bags, cups and straws; 2) ensuring that most plastic products come from recycled plastic and/or 3) substituting non-plastic materials for fossil-derived polymers.
The good news is that an increasing number of consumer brands are responding to popular demand (and to new laws) by setting themselves targets. For example, Unilever wants at least a quarter of its products to be made from recycled plastic by 2030. PepsiCo is aiming for a third and Coca-Cola for half.
The challenge will be in meeting this increased demand for recycled plastics in a way that neither penalizes consumers nor sacrifices product safety.
“Technologically, all polymers are 100% recyclable” explains Sibele Cestari, a research fellow at Queen’s University Belfast whose team is developing a range of building materials from plastic waste-streams. One of the main challenges of recycling plastics is that different polymers (and there are seven main types) generally need to be recycled differently and cross-contamination can be a problem.
There is a difference between mechanical recycling and chemical recycling. With mechanical recycling, polymers of the same group are sifted out of waste-streams, pelletized and re-used in a degraded form – such as in textiles or building materials (this is downcycling). With chemical recycling, a more generous mix of polymers can be cracked under high temperatures (a process called “pyrolysis”) and either turned back into hydrocarbons like oil or naphtha (itself a feedstock for virgin plastic) or “de-polymerized” back into the constituent molecules used to make specific virgin polymers, like producing styrene from polystyrene and then back again (this is upcyling). It is the latter process that is – in theory – infinitely replicable and probably more lucrative. Of course, if any of these chemical processes is to be carbon neutral, the heat will need to be generated by zero-carbon electricity: either directly, in electric arc furnaces for example, or using zero-carbon fuels like hydrogen produced with renewable energy.
Tackling the challenge
Things are moving. Last year industrials giant Dow Chemical engaged Dutch firm Fuenix Ecology Group to turn waste plastics at Dow’s second largest production site, Terneuzen in the Netherlands, into oil and then back into plastics again. This is part of Dow’s goal to incorporate a minimum of 100,000 metric tons of recycled plastics into its products by 2025 and for all of them to be 100% reusable, recyclable, compostable or biodegradable by 2030.
Brightmark Energy, meanwhile, is spearheading one of the largest pyrolysis projects in the world, a $260 million plant in Indiana which aims to transform 100,000 tons of plastic waste per year into 68 million liters of diesel and naphtha to sell to BP. Brightmark claims that this will offset 152 million metric tons of greenhouse gas emissions each year.
And depolymerization is advancing as well. French company Carbios is building a $10 million demonstration plant outside Lyon to break down PET polymers using an engineered enzyme. Martin Stepan, deputy CEO, is enthusiastic: “You can depolymerize any kind of PET waste and make any kind of PET product. You can make a black transparent bottle using a black T-shirt as a feedstock, or you can make a black T-shirt using a transparent bottle”, he told industry outlet Chemical and Engineering News.
100,000 tons may sound a lot but pales in comparison to 38 million tons of plastic produced every year. Nonetheless, these solutions are technically scalable, provided the political will and investment are there. Recent analysis by McKinsey and the Energy Transitions Commission has estimated that plastics decarbonization, meanwhile, could come in at an average cost of $295 per ton, with perhaps as little as 1 cent being added to the price of a plastic soda bottle.
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We need to produce what people want, in a way the planet can afford. Read on for more about how both the Breakthrough Agenda, and action within individual industrial sectors, are stepping up to this challenge.
