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Geopolitical developments since February 2022 and the numerous debates on climate change such as the COP27 are pushing for a greater acceleration in decarbonising the energy sector. The use of geothermal energy for thermal energy production and storage in district heating and cooling (DHC) grids may also be a key element in overcoming short-term energy peaks. This work aimed at evaluating the efficiency and performance of one of the most promising underground thermal energy storage systems, which uses boreholes to store heat or cold (BTES). Numerical simulations allowed for understanding how these technologies can be used as backup systems, or when the energy demand overcomes that supplied by conventional heating systems. The knowledge on how to exploit this energy source shows that a continuous heat extraction from the storage volume can meet both the base and peak load requests for several users, with cumulative energy amounting to 476,000 kWh over the first month. This study proved how the integration of these technologies in DHC contexts can contribute to greater energy and economic savings, becoming an efficient and flexible solution to meet the energy demand from the grid, and also as a backup system.

Air pollution is a growing environmental issue in densely populated urban areas worldwide. Rapid population growth and the consequent increase in energy demand, emissions from industrial activities and vehicular traffic, and the reduction in vegetation cover have in recent years led to increasing concerns about quality of life, especially due to serious health problems associated with respiratory diseases. This study focuses on air quality in the city of Turin in north-western Italy. Continuous one-year monitoring, which collected approximately two million georeferenced data points, was possible using specific devices—palm-sized, wearable, and commercially available sensors—in different parts of the city. This enabled the assessment of the geographical and seasonal distributions of the most commonly studied air pollutants, namely particulate matter (PM) of three size fractions, nitrogen dioxide (NO2), and total volatile organic compounds (TVOCs). The results highlight that the north-western zone and the urban centre are the most polluted areas. In particular, seasonal variations suggest that space heating and cooling systems, together with industrial activities, are the main contributors, more so than vehicular traffic. In this context, handheld devices in an IoT context can provide a reliable description of the spatial and temporal distribution of common air pollutants.

The central role of heating and cooling in energy transition has been recognised in recent years, especially with geopolitical developments since February 2022 which demand an acceleration in deploying local energy sources to increase the resilience of the energy sector. Geothermal energy is a promising and vital option to optimize heating and cooling systems, promoting sustainability of urban environments. To this end, a proper design is of paramount importance to guarantee the energy performance of the whole system. This work deals with the optimization of the technical and geometrical characteristics of borehole heat exchangers (BHEs) as part of a shallow geothermal plant that is assumed to be integrated in an already operating gas-fired DH grid. Thermal performances of three different configurations were analysed according to the geological information that revealed an aquifer at −36 m overlying a poorly permeable marly succession. Numerical simulations validated the geological, hydrogeological, and thermo-physical models by back-analysing the experimental results of a thermal response test (TRT) on a pilot 150 m deep BHE. Five-year simulations were then performed to compare 150 m and 36 m polyethylene 2U, and 36 m steel coaxial BHEs. The coaxial configuration shows the best performance both in terms of specific power (74.51 W/m) and borehole thermal resistance (0.02 mK/W). Outcomes of the study confirm that coupling the best geological and technical parameters ensure the best energy performance and economic sustainability.

Generally, greenhouses are high energy-consuming, sometimes accounting for 50% of the cost of greenhouse production. Geothermal energy plays a very important role in maintaining the desired temperature and reducing energy consumption. This work deals with a project of a hybrid heating plant (97% geothermal energy and 3% gas-condensing boiler) for the innovative Plant Phenotyping Greenhouse at the University Campus in Grugliasco (few km West of the city of Turin). The aim of the study is to testify to the energy efficiency of this kind of hybrid plant as well as its economic sustainability. Numerical simulations of a GRT were used to calibrate the system and verify that the software reasonably modeled the real case. They helped to correctly size the geothermal plant, also providing data about the thermal energy storage and production during on and off plant cycles. The results show a thermal power of 50.92 kW over 120 days of plant operation, in line with the expected energy needs to meet the base load demand. Long-term results further ensure a negligeable impact on the ground, with a thermal plume between 5 and 10 m from the plant, reducing substantially in a few months after switching off the plant.

Water in rock masses is a key factor in geo-mechanics, hydrogeology, mining, geo-thermics, and more. It is relevant in interpreting rock mass behavior (e.g., water-rock interaction or slope stability), as well as in defining heat transfer mechanisms. Pointing out the contribution of secondary porosity in increasing advective heat transfer instead of the conduction phenomenon, this study aims to highlight a different thermal response of sound rocks and faulted zones. Moreover, it provides some methodological suggestions to minimize environment disturbance in data collection and a robust interpretation of the results. An interesting outcrop was identified in a carbonate quarry near Valdieri (north-west Italian Alps): it was studied coupling a geo-mechanical and a thermo-physical approach. In particular, geo-mechanical and photogrammetric surveys, InfraRed Thermography (IRT), and Thermal Conductivity (TC) measurements were conducted. The rationale of the research is based on the fact that, when a substantial temperature difference between flowing groundwater and rocks was detected, IRT can reveal information about geo-mechanical and hydrogeological properties of the rock masses such as a degree of fracturing and joint interconnection. A comparative field and laboratory analysis using different devices enabled a more detailed insight providing values in both dry and wet conditions. A different thermal response was highlighted for the cataclastic zone as well. IRT results showed an evident inverse relationship among the number of joints per meter and the detected surface temperature. This is probably caused by the higher water flow within the cataclastic fault zone. Moreover, low fractured portions of the rock mass presented higher cooling rates and conducted heat far more than those with poor geo-mechanical characteristics (difference up to 40%). A negligible ratio between wet and dried thermal conductivity (about 1%) was also detected in lab measurements, which confirmed that primary porosity is not usually relevant in influencing thermal properties of the sound rock.

Post-wildfires geological hazards are an emerging problem in many places, including areas not typically associated with these events such as the Alpine Region. Hazards connected with post-fire processes such as debris-flows and flood-type events threatens people, infrastructures, services and economical activities. Apart from a few examples, there is a lack of models available to quantify the increase in susceptibility as a result of the modification induced by the wildfires. In this work we test the application of a modified version of the RUSLE, on GIS, to quantify the post-fire erosive phenomena for a case study in the north-western Italian Alps. The results of its application, taking advantage of high-resolution rainfall series and data deriving from field surveys, highlight the marked increase (more than 20 times) in erosion rates, quantified by expressing both the EI (erodibility index), the A (monthly soil loss) and the SL (monthly sediment loss) rise. The months of April, May and June represents the larger share of the total quantities. This is a consequence of the noticeable increase of the Erodibility Index EI, which for the post-fire scenario is more than one order of magnitude higher than the pre-fire one.

In heterogeneous and fractured rock masses, joints are the most important elements controlling the hydraulic conductivity. Joints parameters are therefore crucial for estimating transport of mass and energy in many technical problems (e.g., slope stability, tunnels, geothermal and oil and gas studies). Hydraulic conductivity conceptual models follow well understood generalizations, but their quantitative estimation is not simple. Both laboratory and field tests have many limitations due to representativeness and scale effects. This study proposes a methodology for a preliminary hydraulic conductivity estimation in fractured and/or heterogeneous rock masses through a combination of in-situ geomechanical and geophysical measurements. Contact and no-contact geomechanical surveys were coupled with electric resistivity topographies in two selected test sites within a Mexican geothermal area in the framework of the Ge-Mex H2020 project. The test sites are representative of two different geological settings: a faulted rock mass with expected high hydraulic conductivity in proximity of the faulted areas and an abandoned marble quarry, with very good mechanical characteristics and negligible degree of fracturing. Moreover, both of them are located in remote areas with limited accessibility, in which rapid, time and cost-effective procedures are welcomed and recommended. The preliminary findings of this study were promising: estimated hydraulic conductivities were compared with independent laboratory measurements performed by other researchers showing a good correspondence and reliability. The proposed methodology demonstrated its reliability in decision making, in the technical support and its economical applicability also in similar difficult logistic situations. Article Highlights A combination of in-situ geomechanical and geophysical measurements was adopted for a preliminary hydraulic conductivity estimation; Obtained field data were compared with independent laboratory estimations to assess the reliability of the proposed approach and compare representativeness and scale effects; Even given the difficult logistic conditions and the limitations of the available comparisons the proposed methodology demonstrated its reliability in decision making.

In northern Italy, most greenhouses rely on gas or oil heaters which are sometimes subject to high operating costs. Several greenhouses are nearby quarry lakes, which are the legacy of the expansion of cities in the last decades, including Turin (NW Italy). About 20 quarry lakes were excavated close to the Po riverbed in the southern part of this urban area, along a belt of more than 30 km in length, with an overall volume exceeding 10 million m3 water. The study addresses these artificial lakes as a low enthalpy thermal energy source, potentially providing heat to surrounding agri-business buildings. Detailed temperature monitoring of a large lake quarry was conducted over two years at different depths, measuring the surrounding groundwater level as well. Two different behaviors of the lake during the winter and summer seasons enabled the definition of a quite low water mixing process between the surrounding aquifers and the lake (in the range of 2–4 °C). An evaluation of the heat extraction potential using the lake as a heat source, depending on water temperature and its volume, and a qualitative comparison with groundwater systems are proposed. This study contributes to increasing knowledge on an overlooked resource for sustainable heating.

In many cases it is observed that drains or piezometers used in hydrogeology or landslide mitigation, often at considerable cost, may partly or wholly lose their function—even in few months—due to phenomena such as scaling, fouling, corrosion, etc. Several techniques are already available to overcome these problems, but none has proved decisive and/or effective in every situation. The use of ultrasonic technology in this context has certainly highlighted the complexity of the physical and chemical phenomena that characterize these kinds of problems. Analyzing the results obtained from tens of laboratory tests, it was noted that several factors play a role, and that such factors can somehow influence the effect of ultrasonic waves in removing fouling. However, it was highlighted that, for small diameter drainage (<10 cm in diameter) applications, using continuous or pulse frequencies of 25–20 kHz can give amazing results. The action of these mechanical waves results in the removal of impurities from solid surfaces. Any foreign object lodged or firmly anchored to the internal or external surface of the drain is broken down and crushed by ultrasonic waves. The forecasts for their useful application are optimistic: the working time was estimated, from laboratory tests, in the order of tens of seconds per meter so the time this technique should takes for the operation of cleaning in real cases would be almost 1–2 h for each drain, depending of course on the length, nature and severity of clogging.

A comparative study was carried out aiming at characterizing the thermal conductivity of rocks sampled in a borehole heat exchanger field. Twenty-three samples were analysed with four different methods based on both steady-state and transient approaches: transient divided bar (TDB), transient line source (TLS), optical scanning (OS), and guarded hot plate (GHP). Moreover, mineral composition (from XRD analyses), P-wave velocity, and density were investigated to assess the petro-physical heterogeneity and to investigate possible causes of divergence between the methods. The results of thermal conductivity showed that TLS systematically underestimates thermal conductivity on rock samples by 10–30% compared to the other devices. The differences between TDB and OS, and GHP and OS are smaller (about 6% and 10%, respectively). The average deviation between TDB and GHP, for which the specimen preparation and the measurement procedure were similar, is about 10%. In general, the differences are ascribable to sample preparation, heterogeneity and anisotropy of the rocks, and contact thermal resistance, rather than the intrinsic accuracy of the device. In case of good-quality and homogeneous samples, uncertainty can be as low as 5%, but, due to the above-mentioned factors, usually uncertainty is as large as 10%. Opposite relationships between thermal conductivity and P-wave velocity were observed when analysing parallel and perpendicular to the main rock foliation. Perpendicular conductivity values grow with increasing perpendicular sonic velocity, while parallel values exhibit an inverse trend. Thermal conductivity also appears to be inversely correlated to density. In quartz-rich samples, high thermal conductivity and low density were observed. In samples with calcite or other likely dense mineral phases, we noticed that lower thermal conductivity corresponds to higher density. The presence of micas is likely to mask major differences between silicate and carbonate samples.