Portugal societal exergy accounting - Past and Future

Laura Sofia De Campos Felício

Key information

Authors:

Laura Sofia De Campos Felício (Laura Sofia De Campos Felício)

Supervisors:

Tania Alexandra Dos Santos Costa e Sousa (Tânia Alexandra dos Santos Costa e Sousa); Sofia de Sousa Teives Henriques

Published in

11/30/2017

Abstract

Societal transformations have been reliant on the consumption of energy services such as heat, transport and power, being this evolution enabled by a growing consumption of energy and an increase of its use efficiency. The correct way to evaluate the importance of these energy transfers to society is exergy because this property takes into account their quality, i.e., the maximum amount of work a certain amount of energy may originate (e.g. lift a weight, electrical work, etc.). The current dissertation is based on societal exergy accounting studies for Portugal in order to provide 1) forecasts of exergy demand up to 2030 and 2) a detailed study on the electricity exergy efficiency series 1913-2014. Forecasts show that due to rebound effect it is not possible to have in the same scenario a rapid economic growth and a decrease in greenhouse gas emissions (decarbonized economy) based solely on efficiency improvements. Investing in renewables is mandatory to achieve that goal. Results regarding the aggregated efficiency of electricity show that rather than a continuous increase of efficiency, electricity final-useful aggregate efficiency has grown until the last quarter of the 20th century, around the 1970s and, after that has been decreasing continuously, reaching in 2014 a value similar to 1913 due to the dilution effect caused by the increasing shares of less efficient end- uses. These results emphasize the importance of the rebound and the dilution effects showing that they can partially offset the gains due to technology evolution.