Insights from Past Trends in Exergy Efficiency and Carbon Intensity of Electricity: Portugal, 1900–2014

Abstract

We use the societal exergy analysis to identify periods and factors controlling efficiency dilution and carbon deepening of electricity in Portugal from 1900 to 2014. Besides estimating the carbon intensity of electricity production, we propose a new indicator, the carbon intensity of electricity use, which quantifies CO 2 /kWh of electricity derived useful exergy. Results show final to useful efficiency dilution until World War I (50% to 30%) due to a decrease in share of the high-efficiency transport sector and from mid-1940s to 1960 and mid-1990s onwards (58% to 47% and 47% to 40%) due to an increase in share of the low efficiency commercial and residential sector. Decarbonization from 1900 to mid-1960s, with carbon intensities of electricity production and use dropping respectively from 12.8 to 0.2 and from 33.6 to 0.4 kg CO 2 /kWh due to an increase in thermoelectricity efficiencies and an increase in share of hydro. Then, a period of carbon deepening until 1990 with carbon intensities tripling due to a shift in shares from hydro to thermoelectricity and more recently a period of decarbonization with carbon intensities decreasing to 0.35 and 0.9 kg CO 2 /kWh, due to the increase in renewable electricity despite a dilution in final to useful efficiency.Energies 2019, 12, 534 2 of 22 effects on the lives of women and society in general that resulted from time savings associated with electricity powered domestic devices such as the refrigerator and the washing machines.Due to its social and economic importance and ease of use, electricity has become a significant proportion of the present final energy consumption of OECD (Organisation for Economic Co-operation and Development) countries (22%) [4], second only to oil. Over the next few decades, it is expected that the importance of electricity will increase even more because it is a crucial energy carrier to fuel a sustainable 4th industrial revolution based on electrical and autonomous vehicles, communication, robotization, data gathering and artificial intelligence [5,6]. Additionally, it is essential that many of the end-uses that are currently being provided by fossil fuels, such as mobility, will in the future be provided by renewable electricity [5,7]. Otherwise, the decarbonization of society imposed by the need to decrease the human impact on the climate system will be difficult to achieve.The efficiencies and carbon intensities of electricity production and use are of crucial importance in determining the environmental, social and economic benefits of the imminent energy transition. In order to estimate and locate the opportunities to increase exergy efficiency and decrease carbon intensity, a thorough societal exergy analysis of the whole energy conversion chain, from the primary to final and then to the useful stage, is necessary. To properly estimate primary to final exergy efficiency, one needs to consider the efficiency of electricity generation and distribution, which depends on the energy mix and technical efficiency of the different power statio...

Challenges in Assessing Useful Exergy and Its Significance for Economic Development Studies: An Examination of Mozambique’s Economics Sectors, 1971–2014

“…The end uses for industrial, commercial and services sectors followed the end uses obtained from the literature [7,15,16], which indicate types of end uses, such as mechanical drive, heat, lighting, cooling, and other uses.…”

The Impact of Energy Efficiency on Economic Growth: Application of the MARCO Model to the Portuguese Economy 1960–2014

“…Portugal is a good candidate for this type of analysis: in the last 50 years, there have been both periods of considerable improvements and stagnation in the thermodynamic final-to-useful energy/exergy efficiency of the country [44,76]. Furthermore, previous analyses carried out with Portuguese energy/exergy and economic data have uncovered robust evidence of a close relationship linking thermodynamic efficiency with total factor productivity [42] and overall useful exergy consumption with economic growth [49].…”

“…Data on human labor (engaged individuals, hours worked, population) are obtained from the Penn World Tables (PWT10.0) [3]. Data on primary, final, and useful energy and exergy use, along with the corresponding efficiencies, are obtained from the work of [44,76]. Data on energy prices are obtained from Portuguese-specific databases-that of the Directorate-General for Energy and Geology (DGEG) [82] and the Banco de Portugal long-time series [83].…”

“…The time period covered by all annual time series included in the implementation of the MARCO-PT model is 1960-2014. This range is justified by the best available energy/exergy datasets for Portugal at the time of this analysis [44,76], which have not yet been extended beyond 2014. However, these same datasets have the advantage of covering a significantly long time period going back as far as 1960.…”

Electricity, Exergy and Economic Growth in Mozambique

“…Where: X t is the four endogenous variables vector, so that UEx -data for Mozambique was constructed inspired in the literature (Felício, et. al, 2019;Serrenho et al, 2014;and Ayres et al, 2005) following four steps: the first step was the conversion of FEC into exergy; the second was the allocation of final exergy consumption, per sector, to the different end-uses, the third was the application of the final exergy efficiencies, according to end-uses, to obtain the useful exergy (UEx) data of the FEC, per sectors for Mozambique.…”