The transformation of the energy sector, based on the development of low-carbon technologies, is essential to achieve climate neutrality. The Life Cycle Assessment (LCA) is a powerful methodology for assessing the environmental impact of energy technologies, which proves to be a useful tool for policy makers. The paper is a review of the main LCA studies of power generation systems performed over the past ten years aiming at comparing the energy technologies to identify those with the lowest impact on the environment, evaluated in terms of gCO_2eq/kWh emissions. Screening criteria were established to include only studies of the highest qualitative significance. The authors decided to assign greater weight to emission values reported in more recent studies. For nuclear and renewable energy technologies, most of the emissions are related to the pre-operational phases. Notably, both nuclear and wind technologies, along with other renewable sources throughout their entire life cycle, exhibit significantly lower and less variable emissions compared with conventional gas- and coal-fired technologies.

The selection of suitable sites for the disposal of radioactive waste constitutes a critical component of nuclear waste management. This study presents an original methodological proposal based on the Analytic Hierarchy Process (AHP), designed to support early-stage site screening for a near-surface repository in Italy. AHP could be used to identify appropriate locations, focusing on 51 areas that have already undergone a preliminary screening phase. These areas, included in the National Map of Suitable Areas (CNAI), were selected as they fulfill all the technical requirements (geological, geomorphological, and hydraulic stability) necessary to ensure the safety performance of the engineering structures to be implemented through multiple artificial barriers, as specified in Technical Guide N. 29. The proposed methodology is applicable in cases where multiple sites listed in the CNAI have been identified as potential candidates for hosting the repository. A panel of 20 multidisciplinary experts, including engineers, environmental scientists, sociologists, and economists, evaluated two environmental, two economic, and two social criteria not included among the criteria outlined in Technical Guide N. 29. Pairwise comparisons were aggregated using the geometric mean, and consistency ratios (CRs) were calculated to ensure the coherence of expert judgements. Results show that social criteria received the highest overall weight (0.53), in particular the “degree of site acceptability”, followed by environmental (0.28) and economic (0.19) criteria. While the method does not replace detailed site investigations (which will nevertheless be carried out once the site has been chosen), it can facilitate the early identification of promising areas and guide future engagement with local communities. The approach is reproducible, adaptable to additional criteria or national requirements, and may be extended to other countries facing similar nuclear waste management challenges.

Conductive thermal fields are influenced by convective intrusions. Although small-scale flow intrusions may not have immediate effects, they can significantly impact the thermal behaviour of the system in the medium and long term. In particular, the presence of aquifers near Borehole Heat Exchangers introduces an advective heat transfer component that alters both the undisturbed ground temperature distribution and the thermal relaxation process following heat injection or extraction. When the field is inactive, convective flow may alter the temperature distribution within the field. Conversely, when the thermal field is perturbed, it tends to revert to its original state through a process of thermal relaxation, which is enhanced or hindered depending on the extent of convective intrusions. This study investigates the impact of convection under conditions of inactive and active fields. An experimental monitoring system, equipped with Distributed Temperature Sensing, recorded temperature variations in the field under both inactive and operative conditions at ENEA geothermal site. Two complementary analytical methodologies are proposed to detect and locate convective intrusion on conductive thermal fields. Under undisturbed conditions, aquifer-induced heat removal was quantified by solving the heat conduction equation. The daily volumetric heat generation rate matches the presence of groundwater flow intrusion. Under active conditions the location of groundwater flow was assessed by evaluating deviations in the thermal relaxation rate of individual stratigraphic layers. Layers exhibiting relaxation rates higher than the average are characterized by aquifer-assisted relaxation. Results from the proposed methodology are validated through piezometers that confirm the presence and depth of the aquifer.