The article examines why there are a lot of unused pollution permits in the EU system. It suggests that companies are strategically saving these permits for the future. By doing this, they can reduce their pollution gradually over time, which lowers their overall costs. The researchers used simulations to find that this strategy of saving and using permits can help companies manage their pollution more efficiently in the long run. This means that the large number of extra permits might not be a problem after all, but rather a clever plan by companies to control their pollution and costs effectively.