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The quantitative prognosis and assessment of possible impacts of temperature changes in groundwater due to the geothermal use of the shallow subsurface in urban regions requires process-based numerical models of coupled non-isothermal groundwater flow, heat and mass transport processes and biogeochemical reactive processes. This work therefore aims at developing and implementing numerical methods as well as the required parameterizations to simulate the effects of temperature increases due to heat injection in a groundwater aquifer. Parameter and process models for fluid flow, solute transport, mass transfer processes between aqueous and non-aqueous phases, and microbial growth coupled to contaminant biodegradation are expressed as functions of temperature for this purpose. The developed model is implemented in the OpenGeoSys code and applied in a set of benchmark simulations, where thermal impacts of borehole heat exchangers (BHE) are simulated in an aquifer with a TCE contamination in a residual NAPL source zone. The thermal plumes emitted by the BHEs result in a focusing of groundwater flow due to a viscosity reduction of the heated water. The local increase in groundwater flow as well as an increase in TCE solubility with temperature leads to increased TCE emissions from the source zone. At the same time, increases in microbial growth rates allow for higher TCE degradation rates by reductive dechlorination. Results of the benchmark simulations allow insights into the interactions of the individual processes and potential benefits or conflicts of geothermal use of the subsurface and natural attenuation processes at contaminated sites. Also, the benchmark simulations can be used as test cases for intercomparison and validation of reactive transport codes.

New techniques and methods for energy storage are required for the transition to a renewable power supply, termed “Energiewende” in Germany. Energy storage in the geological subsurface provides large potential capacities to bridge temporal gaps between periods of production of solar or wind power and consumer demand and may also help to relieve the power grids. Storage options include storage of synthetic methane, hydrogen or compressed air in salt caverns or porous formations as well as heat storage in porous formations. In the ANGUS+ project, heat and gas storage in porous media and salt caverns and aspects of their use on subsurface spatial planning concepts are investigated. The optimal dimensioning of storage sites, the achievable charging and discharging rates and the effective storage capacity as well as the induced thermal, hydraulic, mechanical, geochemical and microbial effects are studied. The geological structures, the surface energy infrastructure and the governing processes are parameterized, using either literature data or own experimental studies. Numerical modeling tools are developed for the simulation of realistically defined synthetic storage scenarios. The feasible dimensioning of storage applications is assessed in site-specific numerical scenario analyses, and the related spatial extents and time scales of induced effects connected with the respective storage application are quantified. Additionally, geophysical monitoring methods, which allow for a better spatial resolution of the storage operation, induced effects or leakages, are evaluated based on these scenario simulations. Methods for the assessment of such subsurface geological storage sites are thus developed, which account for the spatial extension of the subsurface operation itself as well as its induced effects and the spatial requirements of adequate monitoring methods.

New methods and technologies for energy storage are required to make a transition to renewable energy sources; in Germany this transition is termed “Energiewende”. Subsurface georeservoirs, such as salt caverns for hydrogen, compressed air, and methane storage or porous formations for heat and gas storage, offer the possibility of hosting large amounts of energy. When employing these geological storage facilities, an adequate system and process understanding is essential in order to characterize and to predict the complex and interacting effects on other types of subsurface use and on protected entities. In order to make optimal use of georeservoirs, a comprehensive use planning of the subsurface is required that allocates specific uses to appropriate subsurface locations. This paper presents a generic methodology on how subsurface use planning can be conducted and how its scientific basis can be developed. Although synthetic, realistic scenarios for the use of the geological underground for energy storage are parameterized and numerically simulated, accounting for other kinds of subsurface use already in place. From these scenario analyses, the imposed coupled hydraulic, thermal, mechanical and chemical processes, as well as mutual effects and influences on protected entities are assessed and generalized. Based on these, a first methodology for large-scale planning of the geological subsurface considering different surface and subsurface usage scenarios may also be derived.

We investigated the onset of preferential flow in heterogeneous porous media using the random walk particle tracking (RWPT) concept. The RWPT model is first used to analyze empirically the required number of particles to achieve accurate concentration distributions in two-dimensional homogeneous media and under uniform flow conditions. The analysis is then extended to randomly heterogeneous systems. By increasing the variance of log-normal hydraulic conductivity fields, the transition between homogeneous and preferential flows is observed. To analyze the degree of preferential flow in the porous media, we provide a diagram that consists of two dimensionless parameters: normalized travel time and distance. All the heterogeneous media synthetically generated show a linear relation in the diagram. The characteristic travel velocity increases with increasing heterogeneity. We found the diagram is a useful tool to analyze preferential flow.

This paper reviews the current research on aquifer thermal energy storage (ATES) and mine thermal energy storage (MTES) in Germany providing descriptions of 3 low-temperature ATES (LT-ATES), 8 high-temperature ATES (HT-ATES), and 2 MTES research sites. While the overview reveals a diverse field of investigations spanning various spatial scales, research objectives, and methodologies, the predominant focus is limited to early-stage research with low technology readiness levels (TRL). The high number of HT-ATES research sites suggests greater research interest compared to LT-ATES. The integration of ATES into district heating (DH) grids in particular is a prominent research focus, yet almost none of the projects are specifically intended for practical implementation. Future research should therefore prioritize real-world demonstration projects and identify key locations, which is crucial for showcasing the benefits of ATES. The need for a streamlined regulatory framework that addresses environmental risks and ensures installation quality and efficient permit procedures is also discussed.

Die Forschung zur Psychiatrie im Nationalsozialismus hat sich zu einem großen Teil auf die Medizinverbrechen der Zwangssterilisation und der Patient*innenmorde konzentriert. Deutlich weniger Aufmerksamkeit erhielten die im psychiatrischen Alltag durchgeführten Therapien und die Beurteilungen ihrer Erfolge. Letztere führten im psychiatrischen „Normalbetrieb“ auch unter den Bedingungen des Nationalsozialismus zu Entlassungen oder zu Verlegungen innerhalb der oder zwischen den Institutionen der Versorgung. Sie konnten aber im negativen Fall auch tödliche Konsequenzen für die Patient*innen haben. Insofern ist es relevant, was Psychiater in dieser Zeit unter „Heilung“ und „Remission“ verstanden, wie und in welchen Abstufungen sie die Beurteilung der Erfolge ihrer Behandlungen auch hinsichtlich der neueren, intensiven somatischen Therapiemaßnahmen und der Arbeitstherapie vornahmen. Diesen Fragen geht der Beitrag im Sinne einer Fallstudie am Beispiel der Universitätspsychiater Gottfried Ewald und Carl Schneider nach, die Lehrbücher verfassten und für ihre unterschiedliche Haltung zu den Patient*innenmorden bekannt sind. Research on psychiatry under National Socialism has largely focused on the medical crimes of compulsory sterilisation and patient killings. The therapies carried out in everyday psychiatric work and the assessments of their success received significantly less attention. Even under the conditions of National Socialism, the assessments of therapeutic success led to dismissals or transfers within or between institutions as a part of the “normal” psychiatric practice. In the negative case, however, these assessments could also have fatal consequences for the patients. In this respect, it is relevant what psychiatrists understood by “healing” and “remission” during this period, how and in what gradations they assessed the success of their treatments - also with regard to the more recent, intensive somatic therapy measures and occupational therapy. The article explores these questions as a case study using the examples of the university psychiatrists Gottfried Ewald and Carl Schneider, who wrote both textbooks and are known for their different attitudes towards patient killings.

Die Forschung zur Psychiatrie im Nationalsozialismus hat sich zu einem großen Teil auf die Medizinverbrechen der Zwangssterilisation und der Patient*innenmorde konzentriert. Deutlich weniger Aufmerksamkeit erhielten die im psychiatrischen Alltag durchgeführten Therapien und die Beurteilungen ihrer Erfolge. Letztere führten im psychiatrischen „Normalbetrieb“ auch unter den Bedingungen des Nationalsozialismus zu Entlassungen oder zu Verlegungen innerhalb der oder zwischen den Institutionen der Versorgung. Sie konnten aber im negativen Fall auch tödliche Konsequenzen für die Patient*innen haben. Insofern ist es relevant, was Psychiater in dieser Zeit unter „Heilung“ und „Remission“ verstanden, wie und in welchen Abstufungen sie die Beurteilung der Erfolge ihrer Behandlungen auch hinsichtlich der neueren, intensiven somatischen Therapiemaßnahmen und der Arbeitstherapie vornahmen. Diesen Fragen geht der Beitrag im Sinne einer Fallstudie am Beispiel der Universitätspsychiater Gottfried Ewald und Carl Schneider nach, die Lehrbücher verfassten und für ihre unterschiedliche Haltung zu den Patient*innenmorden bekannt sind. Research on psychiatry under National Socialism has largely focused on the medical crimes of compulsory sterilisation and patient killings. The therapies carried out in everyday psychiatric work and the assessments of their success received significantly less attention. Even under the conditions of National Socialism, the assessments of therapeutic success led to dismissals or transfers within or between institutions as a part of the “normal” psychiatric practice. In the negative case, however, these assessments could also have fatal consequences for the patients. In this respect, it is relevant what psychiatrists understood by “healing” and “remission” during this period, how and in what gradations they assessed the success of their treatments - also with regard to the more recent, intensive somatic therapy measures and occupational therapy. The article explores these questions as a case study using the examples of the university psychiatrists Gottfried Ewald and Carl Schneider, who wrote both textbooks and are known for their different attitudes towards patient killings.

The numerical simulation of scenarios is a promising approach when quantifying the potential hydraulic, thermal, geomechanical, and chemical effects of subsurface energy and mass storage. Particularly, the coupling of processes is a strong point in numerical simulations. This study defines the geoscientific parameter demand as well as the demand for process understanding for simulating subsurface energy and mass storage, describes the existing numerical codes to conduct the simulations, provides generally valid parameter values, and emphasizes on discussing parameters where only few values exist. In this context, it is exemplified that the parameterizability of the regarded processes is determined by an uncertainty in parameter values (variability or aleatory uncertainty) as well as in the understanding of processes (epistemic uncertainty) as it was suggested by Walker et al. (Integr Assess 4:5–17, 2003 ). The study categorizes the knowledge about parameter values and processes into these uncertainty groups and exemplarily evaluates the impacts of the uncertainties. Using this approach illustrates the concepts needed for calculating prediction errors of numerical scenario simulations, such as sensitivity analyses in the case of statistical data uncertainty and laboratory or field studies in the case of scenario uncertainties.

Injection of CO₂ into gas reservoirs for CO₂-enhanced gas recovery will initiate a series of geochemical reactions between pore fluids and solid phases. To simulate these conditions, the coupled multiphase flow and multicomponent reactive transport simulator OpenGeoSys-ChemApp was extended to take into account the kinetic nature of fluid/mineral reactions. The coupled simulator is verified successfully for the correctness and accuracy of the implemented kinetic reactions using benchmark simulations. Based on a representative geochemical model developed for the Altensalzwedel compartment of the Altmark gas field in northeastern Germany (De Lucia et al. this issue), the code is applied to study reactive transport following an injection of CO₂, including dissolution and precipitation kinetics of mineral reactions and the resulting porosity changes. Results from batch simulations show that injection-induced kinetic reactions proceed for more than 10,000 years. Relevant reactions predicted by the model comprise the dissolution of illite, precipitation of secondary clays, kaolinite and montmorillonite, and the mineral trapping of CO₂ as calcite, which starts precipitating in notable quantities after approximately 2,000 years. At earlier times, the model predicts only small changes in the mineral composition and aqueous component concentrations. Monitoring by brine sampling during the injection or early post-injection period therefore would probably not be indicative of the geochemical trapping mechanisms. One-dimensional simulations of CO₂ diffusing into stagnant brine show only a small influence of the transport of dissolved components at early times. Therefore, in the long term, the system can be approximated reasonably well by kinetic batch modelling.

Sequestration of CO 2 into a deep geological reservoir causes a complex interaction of different processes such as multiphase flow, phase transition, multicomponent transport, and geochemical reactions between dissolved CO 2 and the mineral matrix of the porous medium. A prognosis of the reservoir behaviour and the feedback from large-scale geochemical alterations require efficient process-based numerical models. For this purpose, the multiphase flow and multicomponent transport code OpenGeoSys-Eclipse have been coupled to the geochemical model ChemApp. The newly developed coupled simulator was successfully verified for correctness and accuracy of the implemented reaction module by benchmarking tests. The code was then applied to assess the impact of geochemical reactions during CO 2 sequestration at a hypothetical but typical Bunter sandstone formation in the Northern German Basin. Injection and spreading of 1.48 × 10 7  t of CO 2 in an anticline structure of the reservoir were simulated over a period of 20 years of injection plus 80 years of post-injection time. Equilibrium geochemical calculations performed by ChemApp show only a low reactivity to the geochemical system. The increased acidity of the aqueous solution results in dissolution of small amounts of calcite, anhydrite, and quartz. Geochemical alterations of the mineral phase composition result in slight increases in porosity and permeability, which locally may reach up to +0.02 and 0.1 %, respectively.