Stabilising the concentration of CO2 in the atmosphere at a level of 450 ppm in order to keep global temperature increase below 2 degrees C requires an ambitious climate policy. This study analyses the role of different technologies in the EU-27 with regard to efficiency improvements, fuel switching and energy saving measures under such a climate policy target. The analysis is carried out using the regionalised Pan-European TIMES energy system model, a technology oriented, linear optimisation model. Thereby limited resources and import potentials of various energy carriers, competition among different sectors and the country-specific differences in energy demand are taken into account. As a result, it turns out that the structure of energy use inside the EU-27 is much stronger, influenced by political targets and positions regarding climate protection, energy security and the use of nuclear energy than by available technologies. In the case of climate protection polices and limited use of nuclear energy, the most important measures for the reduction of greenhouse gases are an increased use of renewables, carbon capture and storage, fuel switching and the intensified application of electricity in the end use sectors. Efficiency improvements play an additional role when security of supply is taken into account. (C) 2010 Elsevier Ltd. All rights reserved.