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The European Directives, along with the general notion that wastes are resources, and the effort to reduce the environmental impact in urban environment from waste management, are the driving forces behind waste to energy philosophy. The most sustainable cities in the EU consider that their sustainability is also based on energy recovery from wastes. They all use Waste-to-Energy facilities to treat a significant segment of their waste in order to produce energy in the form of heat and electricity. They do so in a very successful and environmentally friendly way, as they mainly utilise waste fractions that cannot be recycled or reused, and they do not dispose of these resources in landfills. This approach proves that sustainable waste management cannot be achieved without Waste-to-Energy facilities, since a fraction of wastes consists of non-recyclable and non-reusable materials, which provide a significant heating value that cannot be neglected as an energy source. Apart from recycling, Municipal Solid Waste (MSW) treatment is achieved through various processes that aim towards the conversion of waste into useful forms of energy or easily biodegradable, stabilized products. Dedicated treatment methods for getting different refuse derived products that can be used as fuel for producing energy are available. The aim of this paper is to briefly present these methods, review their processes and reveal where their individual energy costs/losses are derived from. A review and a calculation example for the methods of Recycling, Anaerobic Digestion, Composting, Biodrying and combustion are presented concisely. Finally, these methods are compared in terms of energy costs and recovery. Moreover, the calculation methodology of the energy costs of MSW treatment facility is presented. Energy costs/losses are not a synonym for the efficiency of a MSW treatment method, but are an important factor that must be taken into consideration when designing a MSW treatment facility. Furthermore, different waste mixtures will provide different results for this study but the main conclusion remains unaltered: In terms of energy demand for waste management a percentage of methods are energy consuming and others are energy producing, or lead to significant energy savings, which is key action for a sustainable future. Municipal wastes is one of the greatest problems that the modern societies must solve. The current approach is the environmental impact of the method considering the volumes that must be treated and the sustainability of the method. Last but not least, energy consumption must be adopted in each and every human activity so as to achieve sustainable development. [ABSTRACT FROM AUTHOR]