The introduction of severe emission constraints — aiming at the "less than 2°C temperature increase" European target — will trigger drastic changes both in the relative cost-effectiveness and in the dynamics of energy technologies. The POLES model of the world energy system provides a tool for analysing the impacts of emission constraints in a detailed endogenous technology framework, . The seminar will address both the methodological aspects of endogenous technological change in an explicit technology model and the results of different scenarios, illustrating the changes in trajectories introduced by learning by searching, learning by doing and social network effects.