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Maretec, Environment and Energy Scientific Area, DEM, Instituto Superior Técnico IST, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal





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Academic Editor: Jean-Pierre Bédécarrats

Abstract The current method used for calculating societal aggregated exergy efficiencies is reviewed. Cooling is introduced as an end-use category; conversion efficiencies for heating processes are obtained for each energy carrier; and electricity shares per end-use are retrieved for each sector, improving the accuracy of the estimated values of aggregated exergy efficiencies. We show that: 1 cooling uses are a relevant end-use in Portugal and that their introduction decreased overall efficiency by 3.4% in 2009; and 2 disaggregating the heating second law efficiencies for each energy carrier has a significant effect on the aggregated efficiencies of the country, decreasing aggregated efficiency by 1.3% in 2009. We studied two other factors that showed no significant impact on aggregated exergy efficiency: a technological lag of 10 years in the efficiency of stationary mechanical drive devices and the use of a year-specific ambient temperature to compute exergy efficiencies of heating processes. View Full-Text

Keywords: energy; exergy; efficiency; useful exergy; energy use; energy carriers energy; exergy; efficiency; useful exergy; energy use; energy carriers





Autor: Miguel Palma * , Tânia Sousa * and Zeus Guevara

Fuente: http://mdpi.com/



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