Ralf Köber

Kiel University | CAU · Institute of Geosciences

Underground thermal energy storage (UTES) can contribute to renewable energy usability, especially in urban areas with the most demand and available infrastructure. But UTES may interact in those areas with non-aqueous phase liquids (NAPL) by increasing the temperature in storage formations. To determine temperature effects on NAPL dissolution rate...

Despite their potential in heating supply systems, thus far high-temperature aquifer thermal energy storages (HT-ATES) currently lack widespread application. Reducing the potential risks by improving the predictability of hydrogeochemical processes accelerated or initiated at elevated temperatures might promote the development of this technology. T...

In urban areas with frequently occurring contamination by volatile organic hydrocarbons (VOC) possible uncontrolled contaminant mobilization e.g. by volatilization is feared in case of subsurface temperature increases induced by high temperature underground thermal energy storage (HT-UTES) or due to urban heat islands (UHI). However, volatilization...

Zusammenfassung Aufgrund deutlich erhöhter Wärmebedarfsdichten urbaner Räume besteht in besonderem Maße hier die Möglichkeit und Erfordernis, durch eine nachhaltige Wärmeversorgung und saisonale Wärmespeicherung im geologischen Untergrund einen wesentlichen Beitrag zu den national und international gesetzten Klimaschutzzielen zu liefern. Eine effiz...

The operation of seasonal underground thermal energy storages (UTES) as part of renewed heat supply systems can cause amplified temperature variations in the urban subsurface. Therefore, long-term environmental consequences for water extractions by trace elements and heavy metals (TEHMs) are a key point of concern regarding temperature effects on a...

High-temperature thermal energy storage in shallow aquifers can potentially increase ambient groundwater temperatures up to 70 °C or even more. Since an increase in temperature is expected to influence contaminant mass flux into groundwater monitoring the spreading of organic contaminants located in the subsurface is crucial. In numerous former studi...

Aquifer thermal energy storage may result in increases in the groundwater temperature up to 70 °C and more. This may lead to geochemical and microbiological alterations in the aquifer. To study the temperature effects on the indigenous microbial community composition, sediment column experiments at four different temperatures were carried out and t...

The temperature affects the availability of organic carbon and terminal electron acceptors (TEA) as well as the microbial community composition of the subsurface. To investigate the impact of thermal energy storage on the indigenous microbial communities and the fluid geochemistry, lignite aquifer sediments were flowed through with acetate-enriched...

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...

Heating of groundwater by thermal energy storage (TES) poses a potential for the formation of a separate gas phase. Necessary boundary conditions, potential effects and monitoring feasibility of this process were not focused within previous studies. Since the formation of a gas phase could change groundwater flow conditions, hydrochemistry, porous...

Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important role in successful and efficient remediation, especially in heterogeneous systems. Initial sand permeability (k 0) influences on spatial particle distributions were investigated and quantified in homo...

The use of heat storages in the subsurface, especially in urbanized areas, may conflict with existing subsurface contaminations of non-aqueous phase liquids (NAPL). In this work, available data and models regarding temperature influences on parameters for kinetic NAPL dissolution of trichloroethene (TCE) are summarized, discussed and implemented in...

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 fo...

Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the ind...

Die Speicherung von Wärme in oberflächennahen Grundwasserleitern besitzt ein großes Potential zur Verringerung des Bedarfs an fossilen und nuklearen Energieträgern. Aktuelle Forschungsergebnisse geben Hinweise darauf, dass solche Verfahren zukünftig vermutlich in einem weit größeren Maße sinnvoll genutzt werden können als bisher.

Dieser Beitrag untersucht mithilfe numerischer Szenariensimulationen den Einfluss von Wärmespeicherungen im Untergrund auf Altlasten organischer Schadstoffe. Unter den getroffenen Annahmen zeigen die Modellrechnungen, dass der Temperatureinfluss durch Wärmespeicherung in der Schadstoffquellzone zu einer verstärkten Durchströmung, einer erhöhten Lös...

Even today the remediation of organic contaminant source zones poses significant technical and economic challenges. Nanoscale zero-valent iron (NZVI) injections have proved to be a promising approach especially for source zone treatment. We present the development and the characterization of a new kind of NZVI with several advantages on the basis o...

The ambition to apply carbon capture and storage (CCS) requires the provision of effective monitoring approaches that can be applied to detect and to characterize a potential migration or leakage of CO2 and saline formation water into geological compartments between the storage formation and the protected groundwater resource. The sensitivity of mo...

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 amo...

For enhanced gas recovery (EGR) using CO2 as well as for CO2 storage in depleted gas fields it needs to be shown that injection and storage is save and neither population nor environment is exposed to risks during operation or afterwards. This requires the development and application of methods to monitor groundwater, vadose zone and atmosphere. Th...

Aquifer thermal energy storage in urban and industrial areas can lead to an increase in subsurface temperature to 70 °C and more. Besides its impacts on mineral and sorption equilibria and chemical reaction kinetics in an aquifer, temperature sensitively influences microbial activity and thus redox processes, such as sulphate reduction. Microorgani...

A monitoring at geological CO2 storage sites has to meet environmental, regulative, financial and public demands and thus has to enable the detection of CO2 leakages. Current monitoring concepts for the detection of CO2 intrusion into freshwater aquifers located above saline storage formations in course of leakage events lack the identification of...

Most established methods to characterize aquifer structure and hydraulic conductivities of hydrostratigraphical units are not capable of delivering sufficient information in the spatial resolution that is desired for sophisticated numerical contaminant transport modeling and adapted remediation design. With hydraulic investigation methods based on...

IntroductionMicrobially Mediated ProcessesDegradation Rates and Flow VelocityMineral Reactions, Passivation and Degradation RatesConclusions References

The use of reactive tracers combined with conservative tracers offers potential for reactivity information integrated along a certain flow path. In column experiments, several substances were tested to examine their transport behaviours inside a porous medium packed with zero-valent iron (Fe⁰). The results showed that tritium was only conservativel...

Nanoeisen kann als wässrige Suspension in kontaminierte Aquifere zur Sanierung von Schadstoffherden und zur Sicherung von Kontaminationsfahnen mit vergleichsweise einfachen Mitteln injiziert werden. Der Beitrag gibt einen kurzen Überblick zum aktuellen Entwicklungsstand dieser Technologie, über Verfahrensgrundlagen, Erfahrungen aus Wissenschaft und...

Sequenced column experiments were conducted in order to assess the impact of elevated pH caused by two possible reactive media combinations for permeable reactive barriers (Fe°/Oxygen Release Compound (ORC) and Fe°/activated carbon) on the groundwater quality in a lignite sand. In the experiments, pH values > 9,5 downgradient of Fe° and ORC reactor...

Oxygen release compounds (ORC) are one possibility to enhance aerobic degradation in contaminated aquifers. However, some applications have been reported where oxygen concentrations did not meet expectations, this was attributed to ground water composition, e.g., high pH. Column experiments have been performed and the measurements were interpreted...

Multiple column experiments were performed using two commercial iron materials to evaluate the necessity and usefulness of preliminary investigations in permeable reactive barrier (PRB) design for chlorinated organics. Experiments were performed with contaminated groundwater and involved fresh iron granules or altered iron material excavated from P...

Several recent investigations have shown encouraging potential for the removal of arsenic (As) from groundwater by granular zerovalent iron (Fe0). In contrast to previous studies conducted, we have investigated the applicability of this method and the nature of As bonding under conditions with dissolved sulfide. Three column tests were performed ov...

The bulk of arsenic (As) at contaminated sites is frequently associated with iron (hydr)oxides. Various studies ascribe increasing dissolved As concentrations to the transformation of iron (hydr)oxides into iron sulfides, which is initiated by dissolved sulfide. We investigated whetherthis processes can be utilized as a source treatment approach us...

Fe0 has been previously shown to have potential for the removal of arsenic (As) from groundwater. Several sets of coupled experimental columns were run to investigate if As can be removed together with 1,2-DCE(cis) by Fe0-PRBs under different geochemical situations. As was removed with half-life times of approximately 2 h to concentrations of mostl...

The successful dechlorination of mixtures of chlorinated hydrocarbons with zero-valent metals requires information concerning the kinetics of simultaneous degradation of different contaminants. This includes intraspecies competitive effects (loading of the reactive iron surface by a single contaminant) as well as interspecies competition of several...

Kurzfassung Der Vergleich des prognostizierten Abbauverhaltens von Perchlorethen auf der Grundlage eines Säulenversuches und der Monitoringergebnisse der letzten fünf Jahre von der Reaktionswand am Standort Rheine zeigt, dass die Abbauleistung in einem Wandabschnitt mit mehr als 99 % nicht nur andauernd effektiv ist, sondern auch der Prognose entsp...

Kurzfassung Permeable Fe(0)-Reaktionswände werden zunehmend zur In-situ-Behandlung von Grundwasserkontaminationen eingesetzt. Dabei beschränkt sich jedoch der Monitoringansatz zum Nachweis der Funktionsfähigkeit bisher auf Konzentrationsmessungen des Schadstoffs im An- und Abstrom sowie innerhalb der Reaktionswand. Dieser konventionelle Ansatz ist...

Granular zero-valent iron was used for the treatment of groundwater pollution caused by chlorinated ethylenes, mainly TCE, cis-DCE and VC at an industrial site. The rapidly decreasing rates of de-chlorination in the initial phase were attributed to the precipitation of carbonates and the development of hydrogen by anaerobic corrosion. After 70 pore...

The use of a combination of Fe 0 and granular activated carbon as fillings for reactive permeable barriers was investigated for the remediation of complex contaminant mixtures. Column tests carried out with the same concentration of the two model contaminants trichloroethene (TCE) and monochlorbenzene (MCB) showed an increased durability of the act...

The degradation of TCE, cis-DCE and mixtures of both was investigated in laboratory columns packed with zero-valent iron. Analyses show that TCE degradation is only marginally influenced by the addition of cis-DCE whereas the rate constant for cis-DCE degradation is reduced by about 44% upon addition of TCE. A new modelling approach was developed t...

Column tests with groundwater from a contaminated site are carried out to estimate reduction rates of chlorinated hydrocarbons and to predict the long-term performance of a reac- tive barrier. The results of the preliminary investigation are used to determine an appropriate flowthrough thickness for a Fe0 reactive wall. However, validation of the p...

Fe(0) reaction walls (FERW) are reported as a cost effective alternative to classical pump & treat technologies for the remediation of chromate and chlorinated hydrocarbon plumes. But critical and up to now more or less unknown factors controlling the long term performance (in most cases more than 10 years) are the evolution of permeability and rea...

The design of a permeable iron wall depends to a great extent on the transformation kinetics of the chlorinated compounds. Therefore these degradation kinetics of TCE and cis-DCE with commercial iron and their dependence on the properties of the compounds and on the experimental conditions were studied in mixed-batch and column experiments. Since o...

Enth. ausserdem 1 Sonderabdr. aus: Environmental geology. - Beitr. teilw. dt., teilw. engl. Kiel, Universiẗat, Diss., 2001.