Abstract
This paper presents the results of selected simulation runs based on the computer model Green-X. The results suggest that the most significant efficiency gains -measured in terms of premiums to support renewables - can be achieved by optimising national RESE support measures - between two thirds and three quarters of the overall cost reduction potential can be attributed to the optimisation of national support schemes. Further efficiency improvements at a considerably lower level (at about one quarter to one third of the overall cost reduction potential) are possible through an EU-wide harmonisation of support schemes provided that a common European power market exists. Regional coordination represents an essential step towards EU wide harmonisation; half the additional cost benefits of an EU-wide harmonisation can already be tapped through regional coordination compared to the nationally optimised schemes. If a harmonised policy is pursued, technology-specific support is superior to non-specific support with respect to cost minimisation.