Prospects for underground coal gasification in carbon-constrained world

Friedmann, S. Julio; Upadhye, R.S.; Kong, Fung‐Ming

doi:10.1016/j.egypro.2009.02.274

Cited by 103 publications

(44 citation statements)

References 2 publications

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“…Pollutant charged gas leakage from the UCG reactor due to roof rock failure as a thermo-mechanical response of in-situ pressure and temperature conditions recently marks one of the most severe potential environmental impacts [1,6,[15][16][17][18][19]. With focus on the growing public debate on gas leakage affiliated with organic groundwater pollution risks as well as general tar plugging problems, a key future UCG by-product challenge thus lies in better tar production control and aligned organic pollutant minimization in UCG gases [20][21][22][23]. Principle UCG tar related organic pollutant groups, primarily consisting of BTEX, Phenols, PAHs and heterocyclic compounds have been well documented in diverse preceding publications [10,11,21,[24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Innovative thermodynamic underground coal gasification model for coupled synthesis gas quality and tar production analyses

Klebingat

Kempka

Schulten

et al. 2016

Fuel

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Originally published as:Klebingat, S., Kempka, T., Schulten, M., Azzam, R., Fernández-Steeger, T. M. (2016): Innovative thermodynamic underground coal gasification model for coupled synthesis gas quality and tar production analyses. Underground Coal Gasification, Thermodynamic model, Synthesis gas quality, Tar production, Environmental impacts 2 ABSTRACT Underground Coal Gasification (UCG) technology is steadily improving due to high scientific and industrial efforts in currently over 14 countries worldwide. A fundamental UCG objective refers to syngas production for multiple end-uses, accompanied by environmental impact mitigation focusing contaminant reduction. In terms of this topic, the control of groundwater quality endangering tars has been a key problem rarely addressed in UCG publications so far.Considering UCG main sub-processes, operating parameters and tar spectrum knowledge

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Section: Introductionmentioning

confidence: 99%

Innovative thermodynamic underground coal gasification model for coupled synthesis gas quality and tar production analyses

Klebingat

Kempka

Schulten

et al. 2016

Fuel

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“…According to Friedmann and coworkers who analyzed the published data of the commercial UCG pilots, a low carbon content fuel can be produced by combining UCG and carbon capture and storage (CCS), with a considerably lower cost compared to the ex-situ surface gasification. The existence of mature CO 2 capture technologies for decarbonizing the UCG product stream and the proximity of the potential CCS sites to the coal resources [2] are among the reasons that may potentially lead to an economic UCG-CCS process [3,4]. However, Friedmann et that the coupling of UCG-CCS is not addressed in the existing pilot projects nor in the modeling and simulation studies [3].…”

Section: Introductionmentioning

confidence: 99%

“…The existence of mature CO 2 capture technologies for decarbonizing the UCG product stream and the proximity of the potential CCS sites to the coal resources [2] are among the reasons that may potentially lead to an economic UCG-CCS process [3,4]. However, Friedmann et that the coupling of UCG-CCS is not addressed in the existing pilot projects nor in the modeling and simulation studies [3].…”

Section: Introductionmentioning

confidence: 99%

Energy and exergy analysis of alternating injection of oxygen and steam in the low emission underground gasification of deep thin coal

et al. 2017

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• We model UCG process with alternating injection of steam/oxygen.• We used exergy analysis to investigate the practicality of the process.• We show that the alternating injection UCG is practical at low pressure.• Zero emission conversion of coal is not currently practical.• Co-injection of steam/oxygen results in a higher recovery of coal. A R T I C L E I N F O Keywords:Underground coal gasification Alternating injection Exergy analysis Carbon capture and storage A B S T R A C TRecent studies have shown that by coupling the underground coal gasification (UCG) with the carbon capture and storage (CCS), the coal energy can be economically extracted with a low carbon footprint. To investigate the effect of UCG and CCS process parameters on the feasibility of the UCG-CCS process, we utilize a validated mathematical model, previously published by the same authors, that can predict the composition of the UCG product, temperature profile, and coal conversion rate for alternating injection of air and steam for unmineable deep thin coal layers. We use the results of the model to conduct an energy and exergy analysis of the UCG process. We study the effect of various process parameters on the efficiency of the UCG process, the zeroemission recovery factor of coal, and the total CO 2 emission of the process. Moreover, we compare the alternating injection of air/steam with the injection of an air and steam mixture.Exergy analysis shows that the alternating injection of air/steam describes a practical process for UCG at low pressure. However, injecting a mixture of steam and oxygen results in a practical recovery factor of coal higher than the alternating injection process. Additionally, we show that the zero-emission conversion of unmineable deep thin coal resources in a coupled UCG-CCS process, that is not practical with the current state of technology, can be realized by increasing the energy efficiency of the carbon dioxide capture process.

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“…Furthermore, potentially induced changes in overburden hydraulic conductivity may result in pollution of shallow aquifers [9,10]. Especially thermo-mechanical effects and/or fault reactivation may introduce potential migration pathways for hazardous environmental contaminants, mainly composed of organic and inorganic pollutants [4,9,11]. Site-specific coupled thermo-mechanical processes occurring in rocks adjacent to a deep UCG reactor are generally not well known in the field, because of the difficulty to quantify all occurring chemical reactions during the UCG process and their effects on UCG reactor size and shape [12].…”

Section: Introductionmentioning

confidence: 99%

“…In UCG, target coal deposits are developed by directional drilling and then converted into a synthesis gas by sub-stoichiometric combustion, using gasification agents based on oxygen-enriched air and steam. Synthesis gas constituents are mainly hydrogen, carbon monoxide, carbon dioxide and methane in addition to nitrogen and minor components such as sulfuric acid [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

et al. 2016

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Underground coal gasification (UCG) has the potential to increase worldwide coal reserves by utilization of coal deposits not mineable by conventional methods. This involves combusting coal in situ to produce a synthesis gas, applicable for electricity generation and chemical feedstock production. Three-dimensional (3D) thermo-mechanical models already significantly contribute to UCG design by process optimization and mitigation of the environmental footprint. We developed the first 3D UCG model based on real structural geological data to investigate the impacts of using isothermal and non-isothermal simulations, two different pillar widths and four varying regional stress regimes on the spatial changes in temperature and permeability, ground surface subsidence and fault reactivation. Our simulation results demonstrate that non-isothermal processes have to be considered in these assessments due to thermally-induced stresses. Furthermore, we demonstrate that permeability increase is limited to the close reactor vicinity, although the presence of previously undetected faults can introduce formation of hydraulic short circuits between single UCG channels over large distances. This requires particular consideration of potentially present sub-seismic faults in the exploration and site selection stages, since the required pillar widths may be easily underestimated in presence of faults with different orientations with respect to the regional stress regime.

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Prospects for underground coal gasification in carbon-constrained world

Cited by 103 publications

References 2 publications

Innovative thermodynamic underground coal gasification model for coupled synthesis gas quality and tar production analyses

Innovative thermodynamic underground coal gasification model for coupled synthesis gas quality and tar production analyses

Energy and exergy analysis of alternating injection of oxygen and steam in the low emission underground gasification of deep thin coal

Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

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