National energy sustainability and ranking of countriesNational energy sustainability and ranking of countries Κεφάλαιο σε Βιβλίο Book Chapter 2023-07-052021enAll economies need energy to function. However, energy sources are usually finite and energy generation and consumption create pollution and major environmental problems, the most prominent of which is the present climate crisis. Thus, the sustainability of energy is a very important aspect of every national economy. In this chapter, we present two methodologies to assess energy sustainability on the country level using a fuzzy/analytical model called SAFE and a multicriteria method called TOPSIS. We then rank 151 countries on a scale 0–1 using 26 indicators per country. Both models yield rather similar results despite their analytical differences. It becomes clear that the richer countries exhibit higher energy sustainability than poor ones, despite low environmental performance. It also becomes clear that the energy repercussions of rich countries burden the global environment a lot more than poorer ones. This behavior needs urgent attention given that some effects are irreversible.http://creativecommons.org/licenses/by/4.0/Green Energy and TechnologyEnergy Systems Evaluation (Volume 2) Kouikoglou Vasileios Κουϊκογλου Βασιλειος Grigoroudis Evangelos Γρηγορουδης Ευαγγελος Phillis Yannis Φιλλης Ιωαννης Springer Energy sustainability Sustainability assessment Fuzzy evaluation Multicriteria decision analysis Sustainability indicators