DEVELOPMENT OF A DECISION SUPPORT TOOL FOR SUSTAINABILITY ASSESSMENT OF ENERGY RECOVERY SYSTEMS USING REFUSE DERIVED FUEL D. Kolaitis, D. Giannopoulos and M. Founti* Laboratory of Heterogeneous Mixtures and Combustion Systems, Thermal Eng. Section, Mechanical Engineering Department, National Technical University of Athens, Heroon Polytechniou 9, Polytechnioupoli Zografou, 15780 Athens, GREECE * Corresponding author, email: mfou@central.ntua.gr Abstract A decision support tool has been developed in order to assist the procedure of selecting the “optimum” technology among several alternatives using multivariable assessment techniques. The developed tool has been implemented in the case of energy utilization systems that use RDF, a fuel derived from municipal waste. The specific criteria adopted in the selection procedure, have been selected so that to highlight the contribution of each proposed technology in the concept of sustainability. The comparative analysis has shown that while the superiority of “classical” RDF combustion technologies is unquestionable using “conventional” assessment criteria, more “modern” methods like pyrolysis and gasification could emerge as viable alternatives, if environmental issues would be given high priority. Overall, it has been demonstrated that multicriteria methodologies can be effectively used in evaluating thermal utilization and energy recovery systems. Keywords: refuse derived fuel, multicriteria analysis, multivariable assessment, sustainability 1. INTRODUCTION A “multiple criteria” concept has always been involved in the decision- making procedure followed by the human brain, even in cases when supporting tools have not been available. When one has to decide among several alternative solutions, a sub-conscious effort emerges in order to estimate the “global” quality of each option. The difficulty of multicriteria analysis lies mainly in resolving the dilemma of conflicting objectives, since, very often, attributing higher importance to one criterion can be only done at the expense of another. In the present work a decision-supporting tool has been developed, which uses a variation of the well-known PROMETHEE multicriteria method. The outcome of the computational procedure is the positive and negative “flow” of each alternative that is being compared. The relative values of these flows determine the final ranking of each proposed solution. The methodology has been applied to evaluate four different energy recovery technologies used for Refuse Derived Fuel (RDF). The studied assessment problem has a clear multidimensional character, since it can be seen from an environmental, social, financial and/or technical point of view. Consequently, only a