Three-level energy decoupling : energy decoupling at the primary, final and useful levels of energy use

Tese de doutoramento, Sistemas Sustentáveis de Energia, Universidade de Lisboa, Faculdade de Ciências, 2015

Reducing the energy intensity of the economy (energy decoupling) is one of the top priorities of the sustainability agenda. As energy is fundamental for every economic activity, any measure to reduce its consumption must be adequately designed so as not to negatively affect economic growth. Primary energy intensity, which is the standard indicator for energy decoupling analysis, has a high degree of aggregation and therefore is unable to give enough information about its components. A close look at this indicator suggests that the analysis of energy decoupling can be improved with an adequate characterization of energy flows. The objective of this thesis is to improve the understanding of energy decoupling by including in the analysis a detailed characterization of the transformation and use of energy flows in the economy. The work consisted of building models that disentangle economic and energy components from primary energy use. To do so, several methodological tools were used: useful work accounting, decomposition techniques, and input‐output analysis. The proposed models successfully deconstruct primary energy use into several components: 1) structure and efficiency of the primary‐to‐final conversion; 3) structure and efficiency of the final‐to‐useful conversion; 3) useful exergy demand composition and intensity; 4) economic structure; and 5) final demand of non‐energy goods and services. Through these models, it is possible to analyze the relative contribution of each factor on energy decoupling (or coupling) in economic systems. The models were applied to evaluate the trends of primary energy use and energy decoupling in Portugal between 1995 and 2010. The country experienced a relative decoupling driven by three main forces: improvements in primary‐to‐final energy conversion efficiencies, reductions in useful exergy intensity and economic structural changes. This study shows that the analysis of energy decoupling can be improved by the inclusion of three levels of energy use, i.e. primary, final and useful. The present thesis contributes to the literature of energy decoupling, energy input‐output analysis and energy‐related decomposition studies.

Fundação para a Ciência e a Tecnologia (FCT)