It’s accepted wisdom among UK and European policy makers that one of the best ways to lower carbon emissions is through marketisation and cross-border trade. This manifests itself in the phenomenon of what can be called ‘market imagination’, where entirely new markets are created to serve particular policy goals. The problem with these types of markets is that, if designed badly, they can produce perverse outcomes. One such market is the European Guarantee of Origin system. Under this system one ‘certificate’ is created for every MWh of electricity generated from renewable sources. This market is terribly designed, and has meant that green electricity is being double sold and consumers are being mislead.