Every year, hundreds of millions of banknotes are returned to the Bank of England because they’re old, damaged or dirty. Until around 30 years ago, the notes were incinerated – including at the Bank of England’s London offices to help heat the building. But then the Bank of England introduced recycling, along with composting using methods similar to those used for food waste.
Some banknotes continued to be incinerated, with the energy being recovered for electricity generation. The introduction of polymer banknotes in 2016 forced a rethink, as these aren’t compostable. So now the Bank of England is switching to a new form of recycling, in which the notes are processed to make new plastic products like plant pots.