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ODYSSEUS is an R&D project initiated in 2019 and funded by the European Research Fund for Coal and Steel. The project partners from the European coal industry, research organisations and universities focus on the Coal-to-Liquids Supply Chain (CLSC) integration and enhanced assessment of operational, economic and environmental risks during or after mine operation in unfavourable geological settings for potential high coal production areas in European medium- to low-grade coal deposits. For that purpose, technological CLSC integration and optimisation are the main objectives, supported by laboratory- to demonstration-scale experimental activities on upgrading coal-derived liquids and by-product beneficiation, integration of conventional and innovative mine development as well as enhanced techno-economic and environmental risk management. The present contribution provides insights into the CLSC integration strategy developed for a European hard coal deposit and an operating lignite mine based on the combination of in-situ coal conversion with conventional extraction, findings from laboratory- and demonstration-scale coal- liquefaction experiments at surface and in-situ conditions, techno-economic assessments and numerical modelling of coupled processes for the elaboration of a robust environmental risk assessment framework. © 2021 38th Annual International Pittsburgh Coal Conference 2021: Clean Coal-based Energy/Fuels and the Environment, PCC 2021. All rights reserved.

Die Untertagevergasung von Kohle (UTV) ermöglicht die Erschließung nicht konventionell förderbarer Kohleflöze und bietet dadurch Potenzial zur Erhöhung der weltweiten Kohlereserven. Durch die in-situ Kohleumwandlung entsteht ein hochkalorisches Synthesegas, welches entweder elektrifiziert oder zur Gewinnung chemischer Rohstoffe eingesetzt werden kann. Trotz der hohen ökonomischen Potenziale, bestehen durch eine mögliche Reaktivierung von geologischen Störungen, induzierter Seismizität, Oberflächen- setzungen und möglicher Migration von UTV-Rückständen in Grundwasserleitern auch standortspezifische Umweltgefährdungspotentiale. Insbesondere die durch thermo- mechanische Effekte hervorgerufenen Veränderungen der hydraulischen Leitfähigkeit im Deckgestein, können potenzielle Migrationspfade für UTV-Rückstände darstellen. Aufgrund der hohen Investitionskosten von UTV-Pilotanlagen, sind numerische Simulationen gekoppelter UTV-Prozesse von entscheidender Bedeutung für die Bewertung möglicher Umweltauswirkungen. Unsere bisherigen Simulationsstudien zeigen, dass temperaturabhängige Gesteinsparameter in komplexen 3D-Modellen vernachlässigbar sind, wodurch eine höhere Recheneffizienz erzielt werden kann. Die vorliegende Studie umfasst gekoppelte Simulationen eines komplexen 3D-Modells auf der umfassenden Daten- grundlage des im oberschlesischen Kohlebecken ansässigen polnischen Bergwerks Wieczorek. Hierzu haben wir ein thermo-mechanisch gekoppeltes Simulationsmodell zur Analyse von potenziellen UTV-Umweltauswirkungen entwickelt. Unter Berücksichtigung des transpressiven Spannungsregimes im oberschlesischen Kohlebecken, wurden unterschied- liche Nutzungsszenarien untersucht. Die Simulationsergebnisse zeigen, dass ein minimaler Abstand zwischen den einzelnen Reaktorkanälen von etwa der sechsfachen Höhe des Kohleflözes gewährleistet werden muss, um eine hydraulische Verbindung benachbarter Kanäle zu vermeiden. Eine Störungsreaktivierung und Erzeugung möglicher Fluidmigrationswege durch Scher- und Normalverschiebungen wird unter Berücksichtigung der potenziell induzierten Seismizität diskutiert. Unsere Simulationsergebnisse zeigen weiterhin, dass die standort- und nutzungsspezifische seismische Gefährdung durch einen kommerziellen UTV-Betrieb als vernachlässigbar einzustufen ist.

Underground coal gasification (UCG) has the potential to increase the world-wide coal reserves by utilization of coal deposits not mineable by conventional methods. The UCG process involves combusting coal in situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from its high economic potentials, UCG may induce site-specific environmental impacts such as fault reactivation, induced seismicity and ground subsidence, potentially inducing groundwater pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical effects may introduce migration pathways for UCG contaminants. Due to the financial efforts associated with UCG field trials, numerical modeling has been an important methodology to study coupled processes considering UCG performance. Almost all previous UCG studies applied 1D or 2D models for that purpose, that do not allow to predict the performance of a commercialscale UCG operation. Considering our previous findings, demonstrating that far-field models can be run at a higher computational efficiency by using temperature-independent thermo-mechanical parameters, representative coupled simulations based on complex 3D regional-scale models were employed in the present study. For that purpose, a coupled thermo-mechanical 3D model has been developed to investigate the environmental impacts of UCG based on a regional-scale of the Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is 10 km 10 km 5 km with ten dipping lithological layers, a double fault and 25 UCG reactors. Six different numerical simulation scenarios were investigated, considering the transpressive stress regime present in that part of the Upper Silesian Coal Basin. Our simulation results demonstrate that the minimum distance between the UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic communication between the single UCG reactors. Fault reactivation resulting from fault shear and normal displacements is discussed under consideration of potentially induced seismicity. Here, the coupled simulation results indicate that seismic hazard during UCG operation remains negligible with a seismic moment magnitude of MW < 3.

In this study the possibility of using RCM to simulate prechamber gas engines was under investigation. The main effort was focused on pressure trace analysis and high speed flame visualisation. Rate of heat release and flame speed were used as indicators of the combustion process dynamics. The results show that the prechamber broadens the operating range of the RCM in every studied aspect. In case without prechamber the flame exhibits features of laminar flame making the combustion process prolonged. The prechamber in turn, compensates very low turbulence and therefore makes the RCM suitable for simulating prechamber gas engines.

In this study the possibility of using RCM to simulate prechamber gas engines was under investigation. The main effort was focused on pressure trace analysis and high speed flame visualisation. Rate of heat release and flame speed were used as indicators of the combustion process dynamics. The results show that the prechamber broadens the operating range of the RCM in every studied aspect. In case without prechamber the flame exhibits features of laminar flame making the combustion process prolonged. The prechamber in turn, compensates very low turbulence and therefore makes the RCM suitable for simulating prechamber gas engines.