The dena-Leitstudie Integrierte Energiewende develops and compares transformation pathes for the energy system in Germany with the objective to attain the climate-political goals by 2050. It pursues an innovative cross-sector scenario approach. At the same time, it is based on the branch knowledge of more than 60 partners from all relevant sectors and on the continuuos exchange with important actors from politics, society and science. The objective is to give impulses for designing the energy system by 2050. ewi ER&S is the main scientific advisor to the study. The central results of the study say that Germany will be able to attain its goals to reduce greenhouse gas emissions by 80 as well as by 95 % up to the year 2050 if the strains in all sectors are increased. Therefore, the roll-out and system integration of renewable energy sources must be forced, the end energy consumption has to be reduced by extensive energy efficiency efforts, and synthetic regenerative energy sources must be used on a big scale. A broad mix of technologies and energy sources makes the transformation of the energy system more cost-efficient than a fortified use of electricity-based applications.