Population growth, rising per capita incomes as well as changing consumption patterns especially in developing countries are key drivers for increased energy consumption. Current energy provision is however not sustainable and leads to air pollution and climate change through CO2 emissions. In their Kiel Policy Brief, the IfW researchers Matthias Weitzel and Alvaro Calzadilla line out different versions of future energy systems which differ in the degree of centralization and the share of renewables and other low-carbon technologies such as nuclear or carbon capture and storage (CCS). They stress that the ideal energy system depends on local circumstances, for example for rural electrification a more decentralized energy provision might be favorable where the situation will be different for countries with an existing grid. Despite the need for differentiation, there is a need to act soon under a global long term vision to avoid lock-in effects by power plants that pre-determine emissions for several decades.