The switch from the current energy system that is mainly based on fossil carbon to a sustainable energy system with alternative energy curriers (AEC) - renewable, CO2-poor or - free sources of energy - is of central importance for a sustainable energy- and economic-system. The most important AEC are: bio-ethanol, biogas, biodiesel, and other AEC based on biomass, e.g. 2nd and 3rd generation biofuels like e.g. Bio-ethanol from Lignocelluloses (raw materials for production are all cellulosic materials, e.g. grass, straw, wood and different remainder and waste products from the agriculture and wood industry as well as local wastes and residual substances), BtL fuels - they offer the largest quantity potential after current level of knowledge under the bio fuels, since the pallet of raw materials is very large and all plant components can be used - as well as electricity and hydrogen from renewable energy sources and synthetic fuels. In addition, there are possible AEC from fossil sources like e.g. LNG, CTL, GTL¿ The core objective of this project is it to analyze whether and under which circumstances, to which extent and when these alternative sources of energy could be economically of importance in Austria in the future (inclusive external costs). Their potentials, costs, environmental aspects, cumulated energy and necessary promotion strategies will be analysed in a dynamic context, whereby technological learning effects will be considered. The methodic of approach of the analysis consists in principle of a dynamic general survey of the alternative sources of energy among themselves as well as with the conventional sources of energy, whereby mutual reciprocal effects and factors of influence are considered. In order to be able to evaluate the long-term perspectives of AEC at least the following influence parameters in scenarios will be considered: - possible developments of the energy price level and the energy demand; - global developments (particularly regarding learning effects) - Environment, energy and transport policy in Austria and on EU level. Depending on these parameters scenarios are developed, depicting which alternative sources of energy are feasible on a long-term basis, until 2050 in Austria under different developments of these influence parameters, and which can achieve a critical mass and relevant potential. Based on this constructing analyses of sensitivity are accomplished, in order to test the stability of the possible market entrance of the respective alternative sources of energy regarding the changed parameters. From these analyses it will be derived which market diffusion of the AEC is to be expected in a dynamic context and which AEC has a special relevance in Austria in the short to medium-term. The most important results of this project will be concrete action plans for policy makers for the least-cost dynamic development of these potentials in the form of strategies with the necessary accompanying energy-political instruments. These strategies are based on scenarios representing which AEC under which economic and political circumstance as well as with which learning rates to which extent will penetrate into the market and when. Finally, recommendations for the future priority-setting of technology research and development in the field of sustainable AEC in Austria will be derived from it.