A long-term vision for a sustainable energy system needs to address a multitude of challenges. Policy and socioeconomic aspects are crucial but the contribution of science and technology will be of paramount importance as well. The talk will present and discuss a robust transformation path over the next 50-100 years that can ensure economic development worldwide and access mitigation through a consistent decarbonization of all energy sectors. Associated pitfalls and risks will be also included in the discussion. Setting the right priorities, making tough decisions and starting immediately are thereby a must.