From electrification to decarbonization: Insights from Portugal's experience (1960–2016)

Deep electrification powered by renewable sources has emerged as a pivotal strategy for achieving ambitious CO2 emission reduction targets. However, the true impact of electrification on decarbonization remains inadequately measured because the whole energy chain has not yet been fully considered. This study combines Societal Exergy Accounting and Logarithmic Mean Divisia decomposition analysis to quantify the main drivers of relative (de)carbonization in Portugal from 1960 to 2016. The results reveal a significant increase in the carbon intensity of useful exergy from 250 to 380 tons CO2/TJ during the late 1990s, followed by a decline to 280 tons CO2/TJ in the 2000s. These changes were driven by fossil fuel dependency and the efficiency and structure of the energy system. Decarbonization was facilitated by electrification when the following three conditions were met: (1) end-use electrification was at least a third of total useful exergy consumed, (2) renewable resources were at least a third of overall mix (above 33%) and (3) natural gas was at least a third of the mix of fossil fuels used for electricity generation. (above 30%). Policies promoting fossil fuel use for economic development led to the peak in carbon intensity of useful exergy in the 1990s while investments in renewable resources for electroproduction facilitated effective relative decarbonization later. Based on the current structure and efficiency of the energy system, policy recommendations include prioritizing investments in renewables, enhancing final-useful efficiency, and promoting the electrification of mechanical drive end-uses.