Renewable energies (RE) represent a cornerstone to steer our energy system in the direction of sustainability and supply security. Generating electricity, heat or biofuels from renewable energy sources has become a high priority in the energy policy strategies at national level as well as at a global scale. Challenging goals for these "new" supply options to meet our energy demands have been set, e.g. at European level by the commitment of meeting 20% of the overall energy demand from renewable energy sources by 2020. A broad set of different RE technologies and resources exist today. Obviously, for a comprehensive investigation of the future RE development it is of crucial importance to provide a detailed investigation of the country-or region-specific situation-e.g. with respect to the potential of the certain RE's in general as well as the part that can be realised in the near future. It is the core objective of this paper to fulfil above-mentioned constraints, aiming to present an overview on the RE potentials and prospects globally-but based on region- and/or country-specific assessments of the resource conditions, the overall energy system boundaries and the related energy policy framework. Thus, a topical focus is put on both the near to mid future up to 2020 and the long-term perspective, indicating besides theoretical and technical potentials also the realisable mid- and long-term potentials referring to the time-horizon between 2030 and 2050 and prospects for the various renewable energy options. Future prospects are discussed by means of analysing energy policy scenarios as conducted for the International Energy Agency (IEA)'s "World Energy Outlook"-series. in this context, emphasis is given on the illustration of the possible contribution of renewable energies to power supply. (C) 2008 Elsevier Ltd. All rights reserved.