Diminishing natural resources and global climate change are threatening the peaceful course of human development. A fundamental prerequisite for alleviating these dangers is to convert our energy system to renewable generation technologies that neither consume exhaustible resources nor degrade environmental quality despite continuous operation. Therefore, also, the questions have to be answered about how the future electricity system should be structured, which techniques should be used and, of course, how costly the shift to renewable electricity might be. This also raises the question of how far we can get with the existing technologies and what costs are to be expected if one applies them at today’s costs, as a worst case assumption. It is apparent, however, that only taking into account currently available technologies at their actual costs would constitute a worst-case cost assumption, since future developments will unquestionably improve economic performance. But on the other hand it is a conservative approach, not overstressing the fantasy with optimistic cost assumptions, and therefore it results in a sound basis for further considerations. These questions have constituted the focus of a study to determine the optimum cost of an electricity supply realized for Europe and near-proximity Asian and African regions (Czisch 2005). In the supply area considered are currently living about 1.1 billion inhabitants with a total annual electricity consumption of about 4,000 TWh. The approach includes the option of supplying electrical energy to national economies not only or mainly from domestic resources but likewise in cooperation with neighbouring countries and distant regions using transmission systems to interconnect all participants within a wide supply area containing huge renewable energy resources. The freedom for international cooperation between the nations opens up synergetic benefits. Many of the nations within the area of consideration are emerging nations bounding on Europe with renewable potentials far in excess of national demand. Due to this circumstance, the possibilities of wide-area interconnection promise unprecedented economic and technical benefits for all participating nations. The investigations have confirmed that a totally renewable electricity supply is well within the range of current technology, delivering the electricity at costs if at all only slightly above the current cost of electricity even if future equipment cost reductions are ignored.