Pore water in the containment providing rock zone (CRZ) and groundwater from the surrounding aquifers provide the chemical initial conditions and boundaries for reactive transport simulations of radionuclide migration in the context of radioactive waste disposal. Hydrochemical differences between the two hydrogeological domains lead to gradients in the pore water profile across the CRZ, which affect sorption, diffusion, and thus migration of radionuclides such as uranium. However, pore water and groundwater compositions differ on the spatial and temporal scales relevant to safety assessments. To quantify the impact of this variability, we performed one-dimensional reactive transport simulations of uranium migration through Opalinus Clay using the geochemical code PHREEQC, varying both initial and boundary conditions. Our results show that uranium migration distances differ by several decametres over one million years depending on the initial pore water composition in the CRZ. Variations in groundwater chemistry only affect natural uranium concentrations close to the contacts between CRZ and its bounding aquifers. Consequently, the pore water composition in the CRZ is more decisive for uranium migration than hydrochemical variations in embedding aquifers.
Large-scale thermal use of shallow groundwater is often constrained in cities because temperature plumes can extend far beyond project boundaries and affect third-party water rights. Unidirectional Aquifer Thermal Energy Storage (UD-ATES) addresses this by reversing the conventional open-loop arrangement. The injection well is placed up-gradient and the production well down-gradient. During summer cooling, warmed return water is injected up-gradient; the resulting warm plume is carried by the natural groundwater flow to the down-gradient well and can be recovered in the following heating season. Conversely, during the heating season, cooled water is injected up-gradient; the resulting cold plume drifts down-gradient and can be recaptured for cooling in the next summer. This configuration is particularly suited to shallow, highly permeable aquifers with pronounced natural gradients, settings in which classical ATES suffers from advective losses, while also minimizing off-site thermal impacts that complicate permitting.At the State Hospital Graz South site (Austria), we surveyed and characterized the aquifer and built a coupled groundwater-flow and heat-transport model to design a UD-ATES well pair tailored to local conditions. The optimized spacing between injection and production wells is ∼463 m, aligning transport time with the seasonal load profile with a peak thermal power of 1.25 MW (60 L s−1ΔT>3.5 MW using three pairs of wells appears to be feasible at the location in question. These findings support UD-ATES as a practical pathway to decarbonize large, space-constrained consumers in high-flow aquifers while safeguarding neighbouring groundwater uses.
Climate change exerts substantial adverse effects on water resources within the catchment area of Lake Velence in Hungary, intensifying conflicts among stakeholders and diverse water users. This region, characterized by rapid urbanization and economic expansion, also exhibits ecological heterogeneity, including significant wetland areas, some designated as Ramsar sites. At the same time, population growth and modern real estate development have led to a high density of solar panel installations, resulting in above-average per-property renewable energy production capacity across the country. This study proposes an inter-basin water transfer system to mitigate the hydrological impacts of climate change, leveraging the area's topography and solar energy production potential by integrating pumped hydro storage reservoirs and surplus solar energy to transfer water from the adjacent Váli-víz watershed is considered. The ecological flow requirements of the donor area are also considered to protect its ecosystem. The objective is to design a sustainable, low-carbon water replenishment system that addresses the region's economic, social, and ecological requirements. By synchronizing excess solar energy production with pumped hydro storage systems, the approach ensures dual functionality: renewable energy storage and strategic water supply enhancement for Lake Velence, thus increasing the system and the area's resilience under climate stress.
Effective geothermal resource development requires sophisticated computational tools integrating different physical and chemical processes. This work describes a novel coupling of GOLEM, an open source simulator for thermal-hydraulic-mechanical modeling based on the MOOSE multiphysics framework, with the PHREEQC geochemical solver. GOLEM solves coupled partial differential equations governing subsurface fluid flow, heat transfer, conservative mass transport, and mechanical deformation in complex geological environments. PHREEQC is a proven and widely adopted geochemical simulator in the scientific community. The coupling to GOLEM is achieved leveraging an efficient and original wrapper based on the IPhreeqc module. The newly developed coupling of flow, transport and geochemical reactions is validated against standalone PHREEQC by means of 1D RTM benchmarks including both equilibrium and kinetic mineral reactions. A further demonstration of the capabilities of the GOLEM-PHREEQC coupling is shown, on a 2D domain with three distinct geochemical zones.
On 7–9 January 2005 Storm Erwin (known as Storm Gudrun in the Nordic countries) passed across northern Europe causing damage and interrupting power and transportation networks from Ireland to the eastern Baltic region. In northern England the storm was associated with severe river flooding around Carlisle that cut transportation links into the city and necessitated evacuations. In Scandinavia strong winds were reported, resulting in large scale forest damage and power outages. In Denmark, wind energy was impacted as wind speeds crossed the 25 m s−1
Waiwera in New Zealand is a small coastal village with a 50 °C warm reservoir of 400 m thickness directly underneath. Hydrogeological models support water management by providing insights into sustainable extraction from the system. It is artesian and the geothermal water is of meteoric origin percolating down to sufficient depth getting heated. It rises through a fault zone into the shallow and leaky aquifer. Therein the geothermal water mixes with cold fresh groundwater and sea water. The aim of the presented study is to summarise the scientific work over the past decades and the knowledge and progress in process understanding. New radiocarbon dating shows the geothermal water entering the reservoir to be >20 000 years old and underlines the topography driven recharge model. Water management plans helped curbing overproduction. Most recently the springs have restarted discharging geothermal water on the beach.
Digital-rock analysis can now simulate pore-scale flow and geomechanics with high fidelity, yet routine application is still limited by the cost of converting images into pixel-accurate pore masks. Some porosity measurements measure total porosity, but flow requires connected porosity. The need to distinguish between isolated and connected pores is clearly important. The question is why it is difficult to identify connected and unconnected pores. To tackle this, we present a fully labelled 2-D scanning-electron-microscope (SEM) image dataset of outcrop carbonates designed to separate isolated intragranular pores from the connected fracture–pore network. This distinction controls seal performance in carbon-capture and storage (CCS) and radioactive-waste repositories. Each of the 29 056 × 22 952 px images were partitioned into 100 tiles (2048 × 2048 px), annotated by polygon tracing. We then employ and benchmark eight unsupervised computer-vision algorithms: Morphological Gradient, Distance Transform, Local Contrast, Watershed, Global Threshold, Gabor Texture, Refined Morphology, and Edge-based methods. We contribute (i) an open carbonate SEM dataset with labels separating connected and isolated pores, (ii) an efficient polygon-based labelling workflow, and (iii) a quantitative comparison of eight classical pipelines plus a Hybrid voting ensemble. These resources shorten the path from raw images to pore-network predictions, and provide a foundation for future learning-based methods.
The utilization of subsurface reservoirs for geothermal or aquifer thermal energy storage applications requires the drilling of boreholes, which are part of the site infrastructure. For a successful utilization and implementation of this subsurface infrastructure, it is important to know the hydraulic characteristics of the technically connected reservoir system as reliable and early as possible. Comprehensive hydraulic tests required for this are usually carried out after well completion and first filter developing in order to minimize possible influence of the drilling mud and any alteration of the near wellbore area caused by the drilling operation. This normally requires a temporal decoupling of the first well development and the main hydraulic test which is carried out afterwards. In order to optimize this procedure, a combination of well development and hydraulic testing was performed at the High Temperature Aquifer Thermal Energy Storage (HT-ATES) site in Berlin Adlershof. It is shown that hydraulic parameters, such as transmissibility, permeability, productivity index (PI), and skin factor can also be determined already during the well development. For this purpose, a five- and a two-stage step-rate test were carried out, each with subsequent shut-in phases. The combination of analytical and numerical modelling was employed to analyze the aquifer performance. For the analysis, the concept of radially varying permeability around the borehole was developed to account for the area of influence due to drilling mud infiltration and to determine its transient course. The application of a combination of a classic Pressure Transient Analysis (PTA) together with numerical models enabled reliable characterization of the aquifer. The methodical approach developed herein delivers a permeability of 1.5 to 2.0 D and a PI of 1.1 to 1.2 L s−1 bar−1
Soil gas measurements are extensively utilized for seepage detection in natural hydrogen exploration; hydrogen concentration in the soil exhibits significant temporal and spatial variability. We developed an in-soil hydrogen concentration monitoring instrument, named MONHyTOR, capable of up to 1 s sampling rate with up to months of autonomy. Laboratory tests using a closed chamber demonstrate the accuracy of the instrument for diffuse gas flow and a monitoring campaign conducted in the southwest of France yielded several interesting recordings. Each field dataset begins with a hydrogen concentration peak linked to the drilling of the borehole during installation, where parameters from fitting an exponential decay to its decrease indicate the effects of soil type on hydrogen diffusivity and retention in the soil. While the origin of the measured hydrogen is not identified in this paper, our long-term monitoring data suggest that soil gas movements vary with air pressure and temperature values, as well as water circulation in the soil. This paper shows that sampling rate in the order of seconds is appropriate for the commonly observed wavelengths of hydrogen concentration variation in the soil and data processing, and the absence of pump allows for a study on proxies for soil gas diffusivity.
This article presents the new version of the map of critical raw materials hard rock deposits that has been produced in the frame of the GSEU project (Geological Service for Europe). The map displays over 800 medium to very large deposits for 30 Critical Raw Materials (CRM) from the 2023 list of the European Commission, in 33 European countries. We explain the objective of this work and the process and methodology for collecting, compiling and harmonizing CRM data from multiple providers. We also describe the map itself, the information it carries and its availability. As an example of added-value output, we present a pan-European assessment of CRM potential, classified in 4 categories of confidence from “historical or non-compliant resource estimates” to “mineral reserves”. This assessment provides an image of the current known potential for CRM in Europe. Based on this exercise, we discuss the challenges and barriers of compiling and harmonizing mineral resources data at continental scale, and the future perspectives of this work we envision through the EGDI (European Geological Data Infrastructure). We also discuss the limitations of the map and dataset to raise awareness on their proper interpretation and use.
In this contribution the potential impact of spatial variability of pore water diffusion coefficient on uranium diffusion in the Opalinus Clay formation at the Swiss Mont Terri underground research facility is estimated by means of 2D reactive transport simulations. Three lithological facies are considered: sandy, carbonate-rich, and shaly, each with different porosity ranges and chemical sorption capacities due to variations in mineralogy and reactive surfaces. Unconditional geostatistical simulations of porosity with varying correlation lengths (5–20 m) were used to derive spatially variable pore water diffusion coefficients Dp, included in the reactive transport simulations. Two boundary conditions were tested: (1) a linear and (2) a point source, both simulated over one million years. Homogeneous pore water initial conditions or with spatial gradients were considered as well. Results of simulations indicate that the influence of spatial variability is proportional to the correlation lengths of the underlying geostatistical simulations and increases with longer average migration distances. The effect of spatial variability is measured by the geometrical spread of the isolines representing a fixed concentration of dissolved U resulting from spatially variable coupled simulations with respect to the reference homogeneous simulation. This spread reaches 8.5 % and 12.9 % in the shaly facies for the linear and point source respectively. This can be read as a potential uncertainty affecting assessments based on 1D models. These findings highlight the fact that spatial variability cannot be neglected as source of uncertainty on long-term radionuclide transport in potential repository sites.
The safety case for a nuclear waste repository requires the consideration of future evolutions. Methodology and technical implementation for the systematic derivation of a limited number of expected and deviating future evolutions of potential repository siting areas are presented. Evolutions are derived from the analysis of FEP (features, events, and processes) catalogues, which are comprehensive, structured descriptions of a repository system and the interactions and dependencies of processes and components within the repository. In order to apply this work-intensive method to the ninety sub-areas which are currently under consideration in the Site Selection Procedure for the final disposal of high-level radioactive waste in Germany, a generic FEP catalogue is compiled in a first step, from which host rock-specific and area-specific FEP catalogues are created. An analysis of component and process interactions is completed at host-rock level and then transferred and adapted to individual areas, taking site-specific information into account. To facilitate the documentation and analysis of the disposal system and ensure consistency, a sophisticated in-house database solution has been developed.
Underground hydrogen storage (UHS) is emerging as a promising tool for managing surplus energy derived from renewable energy sources. Rock salt (halite) formations, particularly solution-mined salt caverns, offer a secure and efficient storage medium due to their low permeability, self-healing properties, and chemical stability. Laboratory experiments simulating reservoir-like conditions are essential for reducing uncertainties surrounding hydrogen–rock interactions prior to large-scale deployment. This study investigates the response of rock salt to hydrogen exposure under controlled conditions (10 MPa, 60 °C, 30 d) in an autoclave. Two samples from the Eocene Barbastro Formation (Southern Pyrenees), recovered from a deep borehole within a potential salt cavern-type storage site, were tested. The halite samples included impurities such as anhydrite, quartz, feldspars, dolomite, calcite, and phyllosilicates, allowing assessment of non-halite phase reactivity also. Results indicate no significant mineralogical changes after hydrogen exposure. Observed alterations were minor and limited to localised halite recrystallization, slight particle detachment, and occasional chloride precipitation. These findings suggest an overall mineralogical stability of the salt matrix and impurities under the tested conditions and scales. By improving our understanding of hydrogen–rock interactions in evaporitic settings, this study contributes to ongoing efforts to develop safe, science-based solutions for underground hydrogen storage in salt caverns.
The subsurface provides society with many different geo-resources. In addition to the traditional raw materials of coal, oil, and natural gas or drinking water, underground geology has to be used more in future to accomplish climate and energy policy goals as part of the implementation of the energy transition. The prevailing view in the scientific community is that large amounts of carbon dioxide (CO2) from the atmosphere and highly radioactive waste must be disposed of safely – kept away from the biosphere, the human habitat, for geological time periods. In that regard, studies on natural processes that extend over thousands of years help to assess the long-term behaviour of deep geological repositories. Experiments cannot be carried out for such a long time period. However, processes similar to those in the Earth's history can be detected at depth. With regard to the long-term safety of CO22
The division on Energy, Resources, and the Environment (ERE) of the European Geosciences Union (EGU) follows an interdisciplinary approach to serve society with provision of solutions to challenges of our time and in the future. The global energy landscape is undergoing a profound transformation driven by the urgent need to mitigate climate change and achieve net-zero emissions. This transition necessitates a multidisciplinary approach that integrates geoscience with engineering, environmental science, and policy-making to address the complexities of resource utilisation, energy storage, and environmental stewardship. This volume of Advances in Geosciences presents papers covering key themes from recent developments, beside others, in geothermal systems, critical raw materials, carbon cycle dynamics and renewable energy integration, emphasizing the role of interdisciplinary research in overcoming technical, economic, and societal challenges.
To date, most geothermal projects in Germany have focused on deep geothermal systems, while resources at intermediate depths have only been explored to a small extend. However, medium-depth geothermal systems have a high potential for heat generation, even in areas previously considered less favorable for deep geothermal energy, and could make a significant contribution to Germany's heat supply. To accelerate the heat transition and to become independent of fossil fuels, the ArtemIS project aims to assess the medium-depth geothermal systems in Germany, covering all types of geological plays and providing regional information for different geothermal applications. Interactive heat transition profiles are being developed containing all relevant subsurface information required for preliminary geothermal assessment, such as geological descriptions of potential geothermal reservoirs, reservoir thickness, hydraulic and thermal rock properties, and fluid chemistry. In addition, static 3D geological models are being created as the basis for 3D numerical reservoir models using COMSOL Multiphysics to simulate the regional heat potential and different geothermal scenarios, including the performance of hydrothermal doublets. The investigation of well logs and core sample data of the Upper Maastrichtian Calcarenites in the North German Basin indicates a good geothermal potential, but notable lateral and vertical heterogeneities regarding reservoir thickness, grain size or glauconite content throughout the study area need to be considered during exploration. The first COMSOL simulation results highlight the impact of inter-well distance and reservoir thickness on operational parameters such as the occurrence time of thermal breakthrough and cooling rate in a multi-well array. Likewise, a 3D structural model of the Upper Rhine Graben was created and used to assess the regional heat supply, indicating a high potential for heat production in the sedimentary units at intermediate depths. The results of the ArtemIS project will be integrated into the publicly available web platform “Geothermal Information System – GeotIS”, which will provide general information, data, and modelling results in a user-friendly way for non-professionals such as local communities and municipal energy suppliers.
The Permo-Triassic Sherwood Sandstone Group is an important aquifer with potential for both shallow and deep geothermal energy use in the UK. This study investigates the hydrogeological properties of the shallow buried Sherwood Sandstone Group in Northern Ireland, with a focus on its porosity, using borehole nuclear magnetic resonance (BNMR) and petrophysical models (Archie and Waxman-Smits). BNMR and downhole geophysical logging (resistivity, EC, temperature and natural gamma) were carried out on three boreholes drilled into the lower Sherwood Sandstone Group aquifer at depths of about 100 m on Queen's University Belfast campus. The results showed that the porosity calculated from BNMR and the Waxman-Smits model are comparable, demonstrating the relationship between BNMR and petrophysical-derived porosity. The average porosity of the Sherwood Sandstone Group at this location ranges between 14.9 % and 17.6 %, with maximum values ranging between 33.7 % and 40.4 %. However, the results from the Archie model are significantly larger than those of BNRM, confirming its unsuitability for lithologies containing clays, even in small amounts. This study confirms storage capacities in the lower Sherwood Sandstone Group that make it suitable for ATES systems.
Salt weathering, driven by the crystallization of saline solutions within sedimentary rocks, leads to significant material degradation. Key factors influencing this process include salt type, concentration, moisture levels, temperature fluctuations, and pore structure. Environmental conditions and microbial activity further impact weathering, either mitigating or exacerbating its effects. Microorganisms contribute to biological weathering but may also enhance rock properties through biofilm formation or biocementation. Laboratory techniques such as rock testing and micromodel experiments face challenges in replicating complex interactions between microorganisms and salt-bearing porous materials. In this study, we investigated the activity of Paracoccus denitrificans
The AGEMERA project (Agile Exploration and Geo-Modelling for European Critical Raw Materials) advances the exploration of critical raw materials in the EU by deploying innovative, non-invasive geophysical technologies. Funded by the Horizon Europe programme, it aligns with the European Critical Raw Materials Act to enhance resource security and sustainability. Utilising passive seismic methods, drone-based electromagnetic sensing, and muography, the project maps subsurface characteristics across multiple countries in Europe and Zambia. Outcomes are integrated into a dynamic web-based platform for enhanced co-visualisation of different data sets.
The electricity generation sector is undergoing profound transformations via the introduction of wind and solar energies. It is impacted by changing climate conditions, both on the demand and the supply side. The impact of a change in wind and solar resource coupled to the change in demand has however not been studied in regard of its effect on optimal investment decisions. We tackle this issue through the use of regional climate projections coupled to a minimalistic electricity system modeling tool. We find that for the case of France, increasing levels of climate change tend to decrease the optimal penetration of wind energy, while the optimal level of installed solar energy remains constant. We propose that this is explained by the interplay of an average effect coupled to a demand to generation correlation. To the contrary of previous literature, we find that the sole impact of climate change has no adverse consequences on system total costs, with adaptation measures being less attractive economically than their passive counterparts. This highlights the importance of specifying the working hypotheses and phenomena taken into account when issuing policymaking advice, and calls for further research exploring how combining all processes related to climate change impact all relevant elements of the electricity generation sector. We also encourage continued research at the climate and energy interface, to increase the precision and interpretability of similar studies.