Hourly Attributional Prospective Life Cycle Assessment of the Italian Electricity Grid

The environmental profile of the electricity grid varies throughout the year, especially with the introduction of renewables, given their high level of discontinuity. Additionally, positive energy districts emerged as a solution for decarbonizing the building sector, thanks to high levels of self-consumed electricity and the benefits of exporting electricity to the national grid. Most life cycle assessment studies assume a retrospective and static background system for these evaluations. This study presents a prospective attributional life cycle assessment of the Italian national electricity grid for 2024–2040. Hourly factors were derived from a cost-optimization energy model, plus ecoinvent and PREMISE for background modeling. The model projects a sharp decline in fossil-based generation and a significant expansion of solar photovoltaics and wind, which together exceed half of national production by 2040. A total of 16 impact categories were evaluated, revealing decreasing trends in climate change (255 to 141–100 gCO2-eq/kWhe) and others, and rising temporal variability in mineral/metal resource depletion and land use due to renewable intermittency. Applying the method to a positive energy district in Bologna shows that time-resolved factors offer clearer insights than annual averages, especially for season-dependent impacts, and demonstrate substantial reductions in impact by 2040, alongside notable differences between consuming and exporting electricity.