The energy production in the Danube region is predominantly based on fossil and nuclear energy sources contributing to climate change and endangering the ecosystem and lowering the quality of life. While in the last decade the share of renewable energy sources (RES) has grown steadily in final energy consumption, the national energy strategies in the Danube region are still mainly based on fossil and nuclear sources. The international financial crisis and the prolonged recession have pushed the issues of environmental protection and sustainable energy production in the region into the background. The existing RES technologies and plants are in some cases only pilot or small scale projects and they can not spread to their full extent due to political, legal, administrative, economic and technical barriers. Although a lot of studies try to quantify the Renewable Energy Source (RES) potential in the EU and worldwide, the methodology of assessment varies from country to country, from author to author and from time to time. This makes impossible to compare the results because of the diverting assumptions, time horizons and methodology (NREL 2012). Moreover, any informed decision on energy policy should consider the interlinks of energy supply and consumption to ecological, economic and social dimensions. Thus, the goal of the book is to advance in the sound assessment of RES potentials in the Danube Region as weil as in understanding the ecological, economic and societal aspects related with the deployment of those potentials