Invent a greener milk carton for the world

Invent a greener milk carton for the world

The humble milk carton has been part of our lives for so long that it is easy to forget that it was a marvel when it first appeared in 1952. Tetra Pak’s technology made a billionaire of Hans Rausing, scion of the company’s Swedish founding family, who died last week at the age of 93.

The Tetra Pak cartons, made from layers of paperboard and polyethylene, soon displaced glass bottles because they were far lighter and could easily be stacked and distributed. Its aseptic carton, with a layer of aluminium foil that allowed heat-treated milk to remain fresh, followed in 1961.

But every technology has drawbacks and Rausing died at the moment when those of plastic are becoming distressingly obvious. Landfills are stuffed with bottles and cartons, and trillions of pieces of plastic float in the world’s oceans. What happens to the 189bn Tetra Pak containers made last year as they are discarded?

Carton makers such as Tetra Pak and SIG Combibloc of Germany are far from the only contributors to the ballooning volumes of packaging waste. In some ways, they are encouraging recycling. But the rise of the carton shows how complex and difficult is the environmental challenge.

The case for cartons is simple: they may be better than the alternatives. They are easy to transport and a study for German carton makers found that they have 78 per cent less climate impact than glass bottles. They also contain 75 per cent paper and only about 20 per cent plastic.

When collected and taken back to a specialist mill, they are also fairly recyclable. Their various layers separate out into paper, plastic and aluminium fibres when pulped in liquid, allowing the paper fibre to be mixed with virgin wood pulp and turned into cardboard boxes, tissues and the like.

This is the good news; the rest is less hopeful. First, recycling is far from universal even in Europe, which has a better record than the US. Only 47 per cent of materials from the 37bn beverage cartons made for European countries in 2016 were recycled.

Cartons are also prone to a broader paradox — as economies advance, people tend to recycle more but also to consume more. Croatia’s overall recycling rate for packaging in 2016 was 55 per cent, compared with Germany’s 71 per cent, but the average German generated four times as much packaging waste as the average Croatian.

This is a frightening prospect on a global scale. McKinsey & Co, the consultancy firm, estimates that China will comprise 28 per cent of the global packaging market by 2022 and emerging economies such as Vietnam suffer from widespread dumping not only of plastic bottles but of cartons.

Second, paperboard is easier to recycle than the plastic, or the 4 per cent aluminium content of aseptic cartons. In theory, the plastic and aluminium fibres that emerge from the soup of old cartons can be turned to other uses — the metal can become material for roofing tiles, while the polymer can be melted into pellets for gas heating or steam.

In practice, this only happens patchily and, as one study put it, “complete recycling in the strict sense is currently not feasible for beverage cartons”. A carton is carefully bonded and constructed, often with a plastic lid and a straw fixed to the side; what Tetra Pak has joined together is not easily put asunder.

Consumer consciousness of plastic waste is rising sharply, thanks to campaigns against ocean pollution. But people still like the convenience of cartons and they offer many benefits, including access to fresh milk and juice in countries without sophisticated supply chains and refrigeration.

This means companies such as Tetra Pak need to do more to make their products not only useful but also sustainable. In the short term, that involves stronger links with recycling mills and waste companies to ensure that the containers they pump into the world are returned and reused.

Tetra Pak last year agreed a partnership with Veolia, the French waste management group, to recycle more polymer and aluminium fibres from cartons for industrial use in Europe. Along with other carton makers, it is also increasing its use of recycled and environmentally approved raw materials, such as wood pulp from certified forests.

In the long term, the company faces a huge technological challenge to get to what it says is its ultimate aim — to construct cartons entirely out of renewable materials, including recycled plastic. Cartons would then no longer require fresh supplies of polymer from oil and gas refineries.

It sounds improbable but innovation in materials science was what originally enabled the milk carton. That also took a long time to perfect from the first idea of creating a tetrahedral paper carton in 1944 to the manufacture of aseptic containers 17 years later. As Hans Rausing’s father, Ruben, observed: “Doing something that nobody else has done before is actually quite hard.”

The multilayer carton turned out to be a far more useful invention than even the Rausings realised at the time. But, like plastic bottles and aluminium cans, it was imperfect. Making it greener is a worthwhile project.

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