[en] In 2001, the Green Certificate System for Sustainable Energy will become operational. This certificate system will stimulate sustainable production of energy in the Netherlands, which should reduce the Dutch contribution to CO2 emissions. The pros and cons of such a system are discussed it is investigated whether it is ready for implementation. Liberalisation of energy markets in an international context serves as a starting point, because it has an important influence on trends in national energy provision. It is also examined whether anything can be learned from the experience gained with American systems of tradable permits, which show some similarity to the Green Certificate System. Finally, a checklist of characteristics, that the system should meet in order to be an effective part of the environmental and especially climate policy of the Netherlands, is given. If those conditions are satisfied, the system seems ripe for implementation. 7 refs