Italy has a long history of geothermal use, but a comprehensive, updated national assessment has been lacking. This study is the first to systematically evaluate geothermal resources across Italy using the modern geothermal play concept. The primary objective is to provide a standardized, transparent, and reproducible basis for comparing geothermal resources within Italy and across European geological settings. The assessment combines geological, tectonic, geothermal, and utilization data within a GIS framework to map geothermal play types, distinguishing convection- and conduction-dominated systems. Twenty-seven plays are identified and grouped into six main types: volcanic, plutonic, and extensional domains as convection-dominated play types, and foreland basins, orogenic belt, and basement rock provinces as conduction-dominated play types. They form the first geothermal play type map for Italy. From these, 17 key play reservoirs were analyzed using borehole temperature data, lithostratigraphy, reservoir geometries, and petrophysical parameters derived from published literature. Geothermal potential was estimated through volumetric methods for Heat in Place (HIP) and, where possible, Heat Storage Potential (HSP) for medium- and high-temperature Aquifer Thermal Energy Storage (ATES). Probabilistic Monte Carlo simulations addressed uncertainties. Results highlight the exceptionally high geothermal potential of traditional, convection-dominated, plutonic systems in Tuscany, where all power plants are currently operating. In parallel, conduction-dominated sedimentary basins—especially within the Po Plain—exhibit significant potential for direct heat use and thermal energy storage, supported by large reservoir volumes and favorable petrophysical properties. Given the broad distribution of this play type, geothermal resources in Italy have significant potential that extends well beyond traditional magmatic areas. The proposed national framework provides a robust basis for geothermal energy planning, supports cross-border comparison within Europe, and identifies priority targets for future exploration, direct heat utilization, and large-scale subsurface thermal energy storage.

The geothermal sector generates a vast amount of knowledge—from research project data to scientific publications, technical reports, patents, and open datasets—produced by scientists, operators, consultants, public authorities, and funding agencies. However, this wealth of information is often scattered across multiple repositories and platforms, which hampers effective access, integration, and utilization. EGRISE 2.0, developed within the EU-funded Geotherm-FORA project, addresses this challenge as the largest thematic repository for geothermal research and innovation in Europe. The platform aggregates information from EU-funded projects, open access publications, scientific journals, and public datasets hosted on repositories such as Zenodo and Pangaea. Each research product is indexed with detailed metadata, enabling users to search, filter, and explore thousands of documents—currently over 11,000—by criteria such as publication type, funder, country, year, language, or resource access.By consolidating this vast body of knowledge and facilitating its exploration, EGRISE 2.0 allows stakeholders to precisely map the state of R&D in the geothermal industry. Researchers can spot emerging trends, identify gaps, and recognize key contributors, while funding agencies and policymakers can evaluate technological maturity and set priorities for future research and investment. Additionally, the platform facilitates the preparation of innovative project proposals by offering instant access to scientific publications, datasets, and project deliverables.A set of integrated charts further enhances the platform’s value, offering insights such as publication trends, openness over time, and data FAIRness. EGRISE is an open tool available at https://egrise.openaire.eu/. It is powered by OpenAIRE CONNECT, a service to build customizable search portals on top of the OpenAIRE Graph, one of the largest open scientific knowledge graph. In this way, EGRISE 2.0 not only consolidates knowledge but actively empowers innovation, collaboration, and strategic decision-making leveraging on open research information, establishing itself as an indispensable tool for the European geothermal community.

The technology envisioned in the DeepU project (Deep U-tube heat exchanger) is expected to revolutionize the geothermal energy sector, increasing the accessibility of deep geothermal resources for low-carbon heating and power generation. The ultimate project goal is to create a deep (>4 km) closed-loop connection in the shape of a U-tube exchanger by developing a fast and effective laser drilling technology. The project comprises the development of a novel drilling technique and its application via geothermal modeling at selected sites. A prototype of a drill-head has been realized, combining the laser system with drill strings, sustaining the coupled action of laser and cryogenic gas. The fine particles of drilled rocks are ejected to the surface in the gas stream via the borehole annulus. This contribution focuses on the project’s activities related to the laser-rock interactions studied in the experimental laser drilling tests based on previous works (Seo et al., 2022; Li et al., 2022a, 2022b). Three types of lithologies were selected for initial laboratory tests: granite, sandstone, and limestone (50 x 35 x 15 cm). Constant rates of penetration (ROP) upwards of 20 m/h have been achieved in all lithologies with borehole diameter reaching 18 cm. The petro-thermo-mechanical phenomena occurring during laser drilling, such as spallation, melting, and evaporation, were recognized and described. The drilling process was investigated by thermocamera imaging providing information about the most effective process induced by heating the rocks, up to 700°C. The laser working parameters and experimental setup were optimized regarding observed phenomena. In the next step, sections of boreholes were cut out and examined. The microscopic observations on the thermal unaffected and affected rocks’ thin sections have been performed with the use of polarized optical microscopy and scanning electron microscopy revealing micro-fracturing patterns of the rock induced on rock samples by the heating processes. The change of physic-mechanical properties of rocks was investigated and acknowledged in geothermal models. This innovative and comprehensive study revealed macro- and micro-scale phenomena occurring during laser drilling, contributing to the successful development of this new drilling method and subsequently its application for exploitation of geothermal energy from depths below 4 km. This research is funded by the European Union (G.A. 101046937). However, the views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union or EISMEA. Neither the European Union nor the granting authority can be held responsible for them. References Li, G., Shi, D., Hu, S., Ma, C., He, D., and Yao, K., 2022a, Research on the mechanism of laser drilling alumina ceramics in shallow water: The International Journal of Advanced Manufacturing Technology, v. 118, p. 3631–3639, doi:10.1007/s00170-021-08190-0. Li, Q., Zhai, Y., Huang, Z., Chen, K., Zhang, W., and Liang, Y., 2022b, Research on crack cracking mechanism and damage evaluation method of granite under laser action: Optics Communications, v. 506, p. 127556, doi:10.1016/j.optcom.2021.127556. Seo, Y., Lee, D., and Pyo, S., 2022, The interaction of high-power fiber laser irradiation with intrusive rocks: Scientific Reports, v. 12, p. 680, doi:10.1038/s41598-021-04575-z.

We reviewed the historical process that led to the present knowledge of the Larderello geothermal system. This long journey through the human benefit of geothermal resources started in pre-historical times, with the fundamental needs to have warm areas for living, and chemical compounds, i.e., hydrothermal minerals, to exploit. The Larderello area is this: a historical site that evolved to the Present state, passing to be the birthplace of the modern geothermal-electrical industry and today one of the most productive fields in the world. Current knowledge comes from close collaboration between industry and research centres, being a key factor in improving the understanding of the relationships between geological structures and geothermal fluid flow in industrial terms. Due to the efforts of researchers, the evolution of the tectonic and hydrological setting has been revealed: circulating fluids were initially strongly influenced by magmatic and contact-metamorphic supplies, resulting meteoric in the late stage. Permeability is promoted by transfer faults and intersections with coeval normal faults, defining the Miocene-Pliocene Lago pull-apart Basin. In this area, the higher values of heat flow, mantle He isotopes, and shallow depth of the current magmatic source are concentrated, making it one of the most productive field. We conclude underlining the key-role of Earth sciences and of an interdisciplinary approach to face the new challenges of geothermal exploration and sustainable use of geothermal resources.

Geothermal energy, as a renewable and green source for power generation and district heating and/or cooling, is available all year round, at all times of the day, and has great potential for development in any country. However, the exploitation of deep geothermal resources is only possible after detailed characterization of the potential reservoir. In fact, knowledge of the thermo-physical properties of the underground reservoir is crucial for generate a forecast estimation of the geothermal reservoir thermodynamic behavior, as well as for mining risk reduction and optimization of the sound design of geothermal energy production systems.The InGEO project (Innovation in GEOthermal resources and reserves potential assessment for the decarbonisation of power/thermal sectors) aims to develop an innovative exploration workflow integrating geophysical data and other direct and indirect information, organized to make available a sort of decision support system of geothermal projects. It consists of the reconstruction of the crustal and subcrustal structures by joint analyses and interpretations of available and acquired geological and geophysical data (e.g., those provided by mechanical and thermal rock samples laboratory analyses, seismic and gravity anomalies), taking advantage of the different sensitivity that geophysical methods have on physical rock's parameters (temperature and composition). The results will be the input for the geothermal model that will quantify the deep geothermal resource potential of the area. The designed workflow will be tested in a case study area and partially calibrated with developed (hydrothermal) available data. The methodological approach proposed by InGEO is also expected to define the potential local use of geothermal systems by Deep Closed-loop Borehole Heat Exchangers (DBHE) for power generation, district heating and/or cooling. The InGEO results will contribute to the second mission of PNRR “MISSION 2: GREEN REVOLUTION AND ECOLOGICAL TRANSITION”, by expanding the business planning of deep geothermal resource use in Italy.The test area, chosen because it is considered particularly representative of the project topic and of potential reproducibility, includes the sector of the Northern Apennine buried structures, belonging to the Romagna and Ferrara Folds (RFF). The RFF area has been the target of previous geothermal studies highlighting relatively low geothermal gradients within the deep carbonate units (on average 14 °C/km) and more significant thermal gradients (on average 53 °C/km) in the overlying impermeable formations [1-2]. This feature in temperature distribution with depth is clear evidence for fluid thermal convection occurring in the deep-seated carbonate units of Mesozoic age, which constitutes the local geothermal reservoir.[1] Pasquale et al., 2013. Evidence for thermal convection in the deep carbonate aquifer of the eastern sector of the Po Plain Italy. Tectonophysics, 594, 1-12.[2] Pasquale et al., 2014. Heat flow and geothermal resources in northern Italy. Ren. Sust. Energy Rev., 36, 277-285.

Policy HighlightsTo achieve the recommendation stated in the chapter title, we propose the following: Policymakers should mandate that energy decision-making processes be more inclusive, supporting both geothermal representation in large-scale energy deliberation and the inclusive engagement of local communities in individual geothermal projects. Policymakers should foster inclusive societal engagement that goes beyond the minimal requirements of consulting and informing at planning stage, to incorporate processes of deliberation and co-creation with local communities. Geothermal industry actors should practise inclusive societal engagement which is early, continuous, and sensitive to the technical specificities (e.g. local resource, subsurface uncertainties) and social challenges (e.g. low public awareness) of geothermal technologies. Language alignment activities and mutual expert elicitation can support the exchange of knowledge across social-technical disciplines, bridging disciplinary siloes to tackle the problem above.

The dataset represent the Supplementary material of thew manuscript entitled "Map of the top of the Variscan basement in some sectors of Italy" now under revision. The Supplementary material consist of 9 files: input data: dataset_CROP.csv deep_wells.csv domains.geojson thrusts_2.geojson INA_data_point.csv output data: INA_depth_1km.csv ONA_OA_ISA_AF_depth_5km.csv INA_contour.geojson ONA_OA_ISA_AF_contour.geojson

The geoelectrical features of the Travale geothermal field (Italy), one of the most productive geothermal fields in the world, have been investigated by means of three-dimensional (3D) magnetotelluric (MT) data inversion. This study presents the first resistivity model of the Travale geothermal field derived from derivative-based 3D MT inversion. We analyzed MT data that have been acquired in Travale over the past decades in order to determine its geoelectrical dimensionality, directionality, and phase tensor properties. We selected data from 51 MT sites for 3D inversion. We carried out a number of 3D MT inversion tests by changing the type of data to be inverted, the inclusion of static-shift correction at some sites where new time-domain electromagnetic soundings (TDEM) were acquired, the grid rotation, as well as the starting model in order to assess the connection between the inversion model and the geology. The final 3D model herein presents deep elongated resistive bodies between the depths of 1.5 and 8 km. They are transverse to the Apennine structures and suggest a correlation with the strike-slip tectonics. Comparison with a seismic velocity model and well log data suggests a highly-fractured volume of rocks with vapor-dominated circulation. The outcome of this study provides new insights into the complex geothermal system of Travale.

This paper investigates and optimises the thermal performance of deep closed-loop heat exchanger (DCHE) systems by applying a computational numerical approach. The investigated DCHE configuration accounts for two deep vertical boreholes, an injection and a production well, connected by a horizontal borehole at depth and an insulated pipeline at the surface, establishing an effective closed-loop system. First, a parametric sensitivity study explores the effects of the environmental, design and operating variables on the production temperature. The simulation uses realistic geological and geothermal conditions, depths, circulation rates and injection temperatures. Two complex numerical models are then solved for site-specific DCHEs in different geological scenarios: a foreland basin and a convergent margin hosting low-to-intermediate and high-temperature geothermal resources, respectively. Production temperatures beyond 40-60 degrees C and 100 degrees C, sustainable for both heat and electric power generation, are obtained, depending on the geothermal conditions and closed-loop dimensions. Furthermore, circulation rates of 0.02-0.04 m(3) s(-1) are cost-effective, and the system's efficiency and sustainability increase when a fluctuating and periodic heat extraction strategy is employed. When efficiently operated, DCHEs are a viable solution for renewable energy production and should be integrated into the local heat market and distribution network infrastructure. Field of research: Earth and Planetary Sciences; Energy; Environmental Sciences

The paper describes a new experimental deep electrical resistivity acquisition (down to 1600 m) for exploring deep and shallow geothermal systems. The test site is located in the Larderello geothermal area, the oldest geothermal field in the world under exploitation for power production. In this area, many data have been acquired in the frame of previous exploration projects but nowadays several critical issues are still matter of debate: permeability distribution, depth and volume of the magmatic heat source, supercritical fluid condition at depth, and the occurrence of low resistivity anomalies in a dry-steam crystalline and carbonate reservoir. In order to develop new methods for contributing to the hydrothermal reservoir issues, an experimental high resolution 3D Surface-Hole Deep Electrical Resistivity Tomography (SH-DERT) was designed and the Venelle2 well in the Larderello geothermal site, hosted in the crystalline units, was used for the experiment. The design of the in-hole experiment and the results of the deep geoelectrical survey are hereby presented. SH-DERT was properly designed to face extreme conditions at depth characterizing the geothermal well. It provided a 3D resistivity distribution. Transmitting and receiving electrodes were distributed on a large surface (6 km(2)) and in the Venelle2 well (down to 1600 m). The in-hole electrical cable was equipped to be able to operate in very high temperature conditions. The experiment represents a challenge and an opportunity for the applied geophysics in geothermal areas, where a lowest resistivity is highlighted in a zone above the reservoir and the resistivity of the reservoir is higher. Moreover, the relationship between temperature, clay alteration and resistivity can define a challenger to enable better prediction of reservoir temperature distribution from resistivity measurements. It is a potential improvement of the reservoir knowledge and a useful success for exploration drilling.

Sicily hosts many natural manifestations that include thermal waters, gas discharges and mud volcanoes. Due to the significant geodynamic and geological differences, the fluid discharges along a NE-WS-oriented transect that run from the Peloritani Mts. to the Sciacca Plain shows a large variability in water and gas chemical and isotopic compositions. The studied waters are characterized by Ca-HCO3, Ca(Mg)-SO4, Ca-Cl and Na-Cl compositions produced by distinct geochemical processes such as water-rock-gas interactions, mixing between deep and shallow aquifers and seawater and direct and reverse ion exchanges. The gas chemistry is dominated by CO2 to the east and CO2-N-2 to the west of the study area, whereas the central part shows mud volcanoes discharging CH4-rich gases. Water isotopes suggest that the thermal waters are fed by a meteoric recharge, although isotopic exchange processes between thermal fluids and host rocks at temperature >150 degrees C are recognized. Accordingly, liquid geothermometry suggests equilibrium temperatures up to 220 degrees C. The carbon in CO2 and helium isotopes of the emissions from the westernmost sector of Sicily indicate that these two gases consists of up to 40 % of a mantle component, the latter decreasing to the east down to 10% where CO2 of thermometamorphic origin dominates. Accordingly, conceptual models of the fluid circulation for the western, central and eastern sectors are proposed. The regional geothermal reservoir, hosted in carbonates in the western sector and locally outcropping, is of low to medium temperature. Higher temperature conditions (up to 200-220 degrees C) are suggested by geothermometry and probably related to deeper levels of the system. Sicily can be regarded as a potentially suitable area for future investigations to evaluate specific activities aimed at exploiting the geothermal resource.

The technical collaboration program of IEA Geothermal, has, since 1997, through its Working Group 1, undertaken cooperative research studies on environmental and social issues relevant to advancing development of new renewable geothermal resources and sustaining production from existing geothermal systems, by using state-of-the-art technology and best-practice procedures. The goals of the group are: 1) to encourage the sustainable development of geothermal energy resources in an economic and environmentally responsible manner; 2) to quantify and balance any adverse and beneficial impacts that geothermal energy development may have on the environment, and 3) to identify ways of avoiding, remedying or mitigating adverse effects. Tasks include: a) addressing impacts on natural features by monitoring surface thermal feature and ecosystem changes and devising techniques to avoid or mitigate adverse impacts, while encouraging beneficial effects; b) rectifying discharge and reinjection problems, including gas emissions (CO2 & H2S), chemical contamination of water, subsidence, scaling and corrosion, treatment options, and reinjection strategies; c) developing methods of impact mitigation and environmental procedures through an analysis of issues, procedures, efficient policies, protocols, effective compliance, and successful strategies to address social and environmental effects; d) sustaining utilisation by undertaking long-term reservoir simulations, optimizing future operational strategies, improving recharge factors and recovery times, improving reservoir performance, and applying holistic sustainability protocol indicators. This paper summarizes the recent outcomes of that collaboration amongst eight participating countries: Australia, Iceland, Italy, Japan, New Zealand, Norway, Switzerland and the United States. One highlight has been the raising of international awareness of successful mitigation schemes and beneficial environmental or social outcomes.

Based on a joint analysis of geothermal indicators (e.g. temperature map at different depth, surface heat flux) and practical features (e.g. restricted areas, existing research lease), two promising areas in southern Tuscany were identified to perform a more detailed geothermal resource characterization. An area is located on the north-east of the Larderello-Travale geothermal field, and the other one is located on the west of the Mt. Amiata geothermal field. A quantitative geothermal resources assessment was performed in the aforementioned areas of Tuscany by solving numerical thermo-fluid dynamic models and by computing the geothermal potential using the ‘ThermoGIS’ software, as further developed for the Italian case (Trumpy et al., 2016). First of all, geological and geophysical data required for geological and thermo-fluid dynamic modelling were collected and organised. The geological data were used to build a 3D geological model of the two areas of interest suitable for numerical simulations. Static temperature data gathered from the Italian National Geothermal Database together with site-specific heat flow measurements were used to calibrate the simulated steady state temperature distribution. The geothermal potential computed by integrating geological, thermal and petro-physical information implementing the volume method used in ThermoGIS provided estimates of the heat in place and the geothermal technical potential maps. The resulting technical potential in the area close to Larderello –Travale is 330 MWe and in the Mt. Amiata sector is 50MWe. References Trumpy E., Botteghi S., Caiozzi F., Donato A., Gola G., Montanari D., Pluymaekers M., Santilano A., Van Wees, J.D., Manzella A. Geothermal potential assessment for a low carbon strategy: a new systematic approach applied in southern Italy. Energy 103, 167-181, 2016.

A revised surface heat flow map of a sector of the Northern Apennines is presented, constrained by recently available thermal and petrophysical logs from 174 wells drilled for geothermal and hydrocarbon exploration purposes. The borehole temperatures have been corrected for drilling, inclination, and palaeoclimate effects. The corrected temperature data, combined with petrophysical parameters for each individual formation, have been used to derive shallow geotherms (down to a maximum depth of 8 km), which have yielded site-specific heat flow values. These values, once corrected for palaeoclimatic topographic and erosion/sedimentation effects, have been contoured by a kriging procedure to obtain the heat flow map. The map shows a clear distinction between a western zone (the Tyrrhenian Domain) of high heat flow (> 150 mW m(-2)), with closely spaced heat flow isolines, and an eastern zone (the Adriatic Domain) of relatively low (< 70 mW m(-2)), spatially uniform heat flow. The boundary between the two zones is roughly parallel to the axis of the Apennines. Five crustal geotherms (extending to the Moho) and the corresponding rheological profiles confirm that the 70 mW m(-2) isoline corresponds to a major tectonic boundary, across which the thermal, structural, and seismic properties of the lithosphere go through a significant change.

Summary This work presents the two-dimensional stochastic inverse modelling of a magnetotelluric profile from the Larderello geothermal area (Italy). For the first time, the algorithm Particle Swarm Optimization was applied to this kind of field data to investigate a complex electrical structure without the initial assumption given by an external starting model driving the inversion. The outcome was in good agreement with results of previous research with the advantage of a lower data misfit as well as the contribution that the modelling was not initially constrained by a priori information (e.g., from well-log or other geophysical methods) that, in geothermal areas, can be unavailable or even misleading.

Summary We present the results achieved in the framework of different research projects, i.e. the Geothermal Atlas of Southern Italy, the Image, the Descramble and the Gemex Projects, mainly focussing on the thermal aspects of four geothermal fields developed in magmatic setting. We applied an integrated method in order to set-up numerical models able to simulate the conductive-convective thermal structure of the Ischia Island (southern Italy), Long Valley Caldera (eastern California), Acoculco caldera complex (eastern Mexico) and Larderello-Travale (central Italy) geothermal systems. We propose a numerical approach implemented in a Finite Element environment capable to evaluate the contribution of the main variables that characterize the magmatic heat source and the geothermal reservoir. The final 3D thermal models were achieved via the optimization of the available temperature measurements in deep boreholes tacking into account the thermal effects of the interplay between the free convection and the topographically driven groundwater flow, the reservoir permeability and the thermal load released by the parametrized heat source. Our results contribute to better understand the relationship of magmatism to geothermal resources in continental settings.