The objective of this doctoral thesis is to apply different multisectorial models available to analyse the impact that would had on the Catalan economy as a result of the introduction of policies designed to reduce emissions of greenhouse effect gases and save energy, and also at the same time to improve the environmental competitiveness of both individual companies and the economy as a whole. For the purposes of this thesis I have analysed the six greenhouse gases that are regulated by the Kyoto Protocol: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). The range of exercises that I put into practice in this thesis enables us to examine the usefulness of the models applied, and allow to analyse questions that are of great importance for the future environmental and economic conditions of Catalan society.The chapter one contains a brief introduction to computable general equilibrium models, describing the different phases that make up the construction of any applied general equilibrium model, and the advantages and limitations of this type of models. I also give an introduction to the subject of computable general equilibrium models applied to the environment. In the chapter two I construct a social and environmental accounting matrix for Catalonia in the year 2001 (referred to below as NAMEACAT01), which will be used as the numerical basis for all subsequent analyses. A NAMEA (National Accounting Matrix using Environmental Accounts) is simply a double-entry table in which the rows contain the origins of the economic resources and the columns show the uses that economic agents give to the resources concerned.In the next chapter, I define a linear model of emission multipliers using the NAMEA for the Catalan economy. Like income multipliers, emission multipliers can be divided into own effects, open effects and circular effects. This decomposition shows the various channels of income generation and how they affect regional greenhouse pollution.The chapter four I analyses the economic impact of alternative policies implemented on the energy activities of the Catalan production system. Specifically, I analyse the effects of a tax on intermediate energy uses, a reduction in intermediate energy demand, and a tax on intermediate uses combined with a reduction in intermediate energy demand. The methodology involves two versions of the input-output price model: a competitive price formulation and a mark-up price formulation. In chapter five, I use the model proposed by Roland-Holst and Sancho (1995) to assess the economic and social impact of the implementation of different policies to reduce CO2 emissions and improve, at the same time, the environmental competitiveness of enterprises and the private real income in Catalonia. Alternativelly, I also apply a second model, which is an extension of the exogenous determination of production in the input-output quantity model (Miller and Blair, 1985) to a SAM database. Finally, chapter six summarises the conclusions and future research of this study. / La presente tesis doctoral tiene como objetivo efectuar una aplicación de los diferentes modelos multisectoriales, para analizar el impacto que tendría en la economía y la sociedad catalana la implementación de diferentes políticas que nos permitiesen disminuir las emisiones de gases de efecto invernadero y obtener ahorros de energía y al mismo tiempo mejorar la competitividad de nuestras empresas y de nuestra economía. Concretamente para la realización de la presente tesis, hemos utilizamos los seis gases de efecto invernadero regulados por el protocolo de Kyoto: dióxido de carbono (CO2), metano (CH4), oxido nitroso (N2O), hexafluoruro de azufre (SF6), hirofluricarbonos (HFCs) y perflurocarbonos (PFCs). El conjunto de ejercicios que llevamos a cabo en esta tesis permite observar la utilidad de estas aplicaciones, abordando cuestiones de un importante interés para la realidad medioambiental y económica de la sociedad catalana.