The expansion of the renewable energies is one of the supporting strategic pillars for a sustainable climate friendly design of our energy system. Since the start of the renewable use in the nineties and during the dynamic further development the conflicts related to their utilisation have aggravated in different sectors.

This concerns e.g. the wind energy sector with the conflicting areas climate protection on the one hand and the aesthetical impact of the landscape on the other hand. These conflicts are likely to increase if the expansion goals of the Federal Government (Doubling of the renewable share until 2010) and the further conception of the Federal Ministry of Environment (perspective to reach a renewable energy share of 50 percent of the energy supply until mid century) should be realised.

Against this background, after defining and classifying the problem, the study first describes and assesses the individual technological impact of the different utilisation options in the relevant application area of the renewables.

This includes quantifiable efficiency classes on the one hand (e.g. disburdening factor compared to conventional power and heat supply technologies for the sectors greenhouse effect, acidification, material and raw material use) and on the other side not quantifiable effects (e.g. intervention in the interests of nature and landscape protection). This operation step bases on the process chain analysis, an instrument that makes it possible to consider the impacts from "the cradle to the grave". The impacts of the utilisation options are analysed under comparative and evaluative view.

The results of this ecological comparative analysis are, together with further studies with a rather economic and energy efficient focus (e. i.e. assessment of potentials, target achievement factor for the renewable energies under global system view), a basis for the formulation of specifications on the optimised further development of renewable energies in Germany, that are to finally lead to the development of "optimised" development scenarios.

The final part of the study discusses what kind of barriers are opposed to such a further development of the renewable energies and which instruments are to be used to stimulate the relevant market players towards an optimised development of the renewable energies.

The period under review for the study reaches to the year 2020, so that also beyond the already implemente, beneficial energy - political measures for the development of renewable energies, it is necessary to develop further ideas and conceptions and to bundle them into consistent packages of measures.