The European Union's Emissions Trading System is the largest system in the world for trade in greenhouse gases. It used to be a cap-and-trade scheme with a fixed supply of permits. However, a recent reform of the system "punctures the waterbed" by making the supply of permits endogenous. The...

The European Union’s Emissions Trading System, EU ETS, has been reformed, shifting the system from a fixed-cap system into a system with an endogenous supply of permits. This paper discusses how to handle the scheme in project appraisal. The focus is on a few relatively straightforward...