On behalf of RWE AG, Frontier Economics has analysed the implications of the possible introduction of the “550g rule” proposed in the draft of the EC winter package (Art 23 of the Electricity Regulation recast). The 550g rule would restrict access to capacity markets for installations with CO2 emissions at or in excess of 550g CO2/kWhel. The rule is set to apply for existing and future capacity mechanisms (a number of EU member states have already introduced a capacity market, and it is also possible that a capacity market will be introduced in other member states with the intention of guaranteeing future security of supply.)