1 A multiple criteria decision making approach for electricity planning in Spain: economic versus environmental objectives Pedro Linares 1 and Carlos Romero 2* 1 Universidad P. Comillas de Madrid, Spain; and 2 Universidad Politécnica de Madrid, Spain Growing social concern about the environmental impact of economic development has drawn attention to the need to integrate environmental criteria into energy decision-making problems. This has made electricity planning issues more complex given the multiplicity of objectives and decision-makers involved in the decision making process. This paper proposes a methodology that combines several multi-criteria methods to address electricity planning problems within a realistic context. The method is applied to an electricity planning exercise in Spain with a planning horizon set for the year 2030. The model includes the following objectives: total cost, CO 2 , SO 2 and NO x emissions as well as the amount of radioactive waste produced. An efficient social compromise between these conflicting objectives is obtained, which shows the advantages of using this model for policy-making purposes. Keywords: multiple criteria decision making; energy; environmental studies; compromise programming Introduction In the last few decades, modern societies have realised the need for a sustainable development that requires that both economic and environmental resources be allocated efficiently from a social point of view. Unfortunately, this socially-efficient allocation cannot be carried out solely by market mechanisms, because of the existence of environmental externalities, i.e., effects on the environment caused by human activities, not included in the market price. In fact, it is well known that the presence of externalities generates a “market failure”, implying that the allocation of resources provided by the market mechanisms is inefficient. This is especially relevant in the * Correspondence: Prof. C Romero, ETS Ingenieros de Montes (Unidad de Economía), Avenida Complutense s/n, 28040 Madrid, Spain. E-mail: auggiegp@montes.upm.es