The use of grey-based methods in multi-criteria decision analysis for the evaluation of sustainable energy systems: A review

The European energy system is characterized by a high dependence on fossil fuels and energy importation. Renewable energies are a solution to this issue. To change the energy supply, it is necessary to analyze the energy system. Thus, decision-makers face a multi-attribute decision problem. Many sustainable energy systems analyses are characterized by multiple, interrelated parameters and vague information. When the information is vague, it is necessary to implement multi-criteria decision analysis (MCDA) tools that can work with poor data systems. This article reviews appropriated methods and different stages of MCDA problems using grey relation methods (i.e., criteria selection and weighting methods). It is observed that technical criteria are the most evaluated parameters, followed by environmental criteria, in terms of gas emissions. In referring to criteria weighting, the analytical hierarchy process is the most popular tool, especially when it is essential to evaluate the opinion of an expert panel.