The material base of money is rarely noticed by the people who use it. Notes slip from hand to hand, folded, crumpled, tucked into wallets, then eventually withdrawn by a bank when too worn to circulate. Yet the substrate—the sheet on which money is printed—shapes both the note’s lifespan and its ecological footprint. For an industry that prints billions of notes every year, the question of what those notes are made of has become central to sustainability.
For more than a century, cotton-based paper dominated. Stronger than wood pulp and flexible under heavy use, cotton provided a balance of durability and print quality. But cotton production carries costs that are increasingly hard to ignore: it demands large quantities of water and pesticides, and is often tied to exploitative agricultural practices. A single kilogram of cotton fibre can require more than 10,000 litres of water, depending on where it is grown. Multiply that across the tonnes of cotton used for banknote paper, and the environmental toll becomes clear.
Enter polymer substrates. Made from biaxially oriented polypropylene (BOPP), polymer notes first appeared in Australia in the 1980s and have since spread to more than 30 countries, including Canada, the UK, and Nigeria. Their promise is straightforward: polymer lasts two to three times longer than paper, reducing the frequency with which notes need replacing. Longer life means fewer print runs, lower transport emissions, and reduced pressure on printing facilities. Polymer notes are also more resistant to dirt, moisture, and counterfeiting—features that reinforce both security and hygiene.
But the polymer solution is not without dilemmas. Derived from oil, BOPP substrates carry the baggage of fossil fuel dependence. Their durability, while an advantage in use, creates challenges at the end of life. For years, central banks stockpiled shredded polymer waste, unsure how to dispose of it without environmental harm. Only recently have recycling solutions begun to scale. In Canada, old polymer notes are shredded into pellets used in plastic manufacturing, from benches to construction piping. The challenge is consistency—ensuring that all withdrawn notes actually enter recycling streams rather than landfills.
This has opened a third path: hybrid substrates. These combine a cotton paper core with polymer reinforcement, offering the feel and printability of paper with the extended durability of polymer. They represent a “middle road” for countries hesitant to fully abandon cotton or commit to pure plastic. Meanwhile, material scientists are exploring bio-based polymers derived from renewable resources such as cornstarch or sugarcane, which could reduce reliance on oil.
The substrate debate is not just technical—it’s political. Countries weigh the ecological benefits of polymer against public perception (“plastic money” often meets initial resistance) and cost. Cotton notes may be cheaper to produce, but their shorter lifespan raises replacement expenses. Lifecycle analyses conducted by the Bank of England and the Reserve Bank of Australia suggest that polymer’s overall environmental impact is lower, but the margins depend on effective recycling systems. Without them, polymer’s benefits shrink.
For the International Currency Association, the substrate question symbolises a larger sustainability challenge: every choice in money design has ripple effects across ecosystems, economies, and societies. The task is not to find a single “perfect” material but to plan for lifecycles that balance durability, recyclability, and resource efficiency. A greener note is not just one that lasts longer, but one that begins and ends its life without burdening the planet.
In the years ahead, the innovation frontier will not simply be in dazzling new security features but in humble fibres and films. The future of sustainable currency will be measured as much in litres of water saved and tonnes of waste diverted as in its resistance to counterfeiters. The note of tomorrow, in other words, will be judged not only by what it’s worth but by how lightly it weighs on the world.
