The non-profit Plastic Deposit Organisation, responsible for managing Denmark's container deposit system, estimates that this change alone will enable them to collect and reuse approximately 70 million additional bottle caps annually. This equates to 140 tonnes of plastic each year.

https://www.emballagefokus.dk/goer-noget-uden-at-goere-noget...

This assumes a 90% cap return rate before (which seems low) and a 100% return rate afterwards (not in Denmark myself but I can't be the only one to have returned zero of the new caps vs almost 100% before).

The whole thing smells like a made up issue concocted by some company wanting to sell their bottle cap solution.