Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness

Underground coal gasification (UCG) enables utilization of coal reserves, currently not economically exploitable due to complex geological boundary conditions. Hereby, UCG produces a high-calorific synthesis gas that can be used for generation of electricity, fuels, and chemical feedstock. The present study aims to identify economically-competitive, site-specific end-use options for onshore- and offshore-produced UCG synthesis gas, taking into account the capture and storage (CCS) and/or utilization (CCU) of produced CO 2 . Modeling results show that boundary conditions favoring electricity, methanol, and ammonia production expose low costs for air separation, low compression power requirements, and appropriate shares of H 2 /N 2 . Hereby, a gasification agent ratio of more than 30% oxygen by volume is not favorable from the economic and CO 2 mitigation viewpoints. Compared to the costs of an offshore platform with its technical equipment, offshore drilling costs are marginal. Thus, uncertainties related to parameters influenced by drilling costs are negligible. In summary, techno-economic process modeling results reveal that air-blown gasification scenarios are the most cost-effective ones, while offshore UCG-CCS/CCU scenarios are up to 1.7 times more expensive than the related onshore processes. Hereby, all investigated onshore scenarios except from ammonia production under the assumed worst-case conditions are competitive on the European market.

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Optimization of synthesis gas heating values and tar by-product yield in underground coal gasification

Fuel ◽

10.1016/j.fuel.2018.02.039 ◽

2018 ◽

Vol 229 ◽

pp. 248-261 ◽

Cited By ~ 7

Author(s):

Stefan Klebingat ◽

Thomas Kempka ◽

Marc Schulten ◽

Rafig Azzam ◽

Tomás Manuel Fernández-Steeger

Keyword(s):

Synthesis Gas ◽

Coal Gasification ◽

Product Yield ◽

Underground Coal Gasification ◽

Gas Heating

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Chemical Process Modelling of Underground Coal Gasification and Evaluation of Produced Gas Quality for End Use

Energy Procedia ◽

10.1016/j.egypro.2015.07.870 ◽

2015 ◽

Vol 76 ◽

pp. 444-453 ◽

Cited By ~ 9

Author(s):

E. Andrianopoulos ◽

A. Korre ◽

S. Durucan

Keyword(s):

Chemical Process ◽

Coal Gasification ◽

Process Modelling ◽

Underground Coal Gasification ◽

End Use

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Synthesis Gas Composition Prediction for Underground Coal Gasification Using a Thermochemical Equilibrium Modeling Approach

Energies ◽

10.3390/en13051171 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1171 ◽

Cited By ~ 1

Author(s):

Christopher Otto ◽

Thomas Kempka

Keyword(s):

Synthesis Gas ◽

Equilibrium Model ◽

Carbon Capture ◽

Coal Gasification ◽

Carbon Capture And Storage ◽

Equilibrium Composition ◽

Operating Conditions ◽

Underground Coal Gasification ◽

Modeling Approach ◽

Wide Range

Underground coal gasification (UCG) is an in situ conversion technique that enables the production of high-calorific synthesis gas from resources that are economically not minable by conventional methods. A broad range of end-use options is available for the synthesis gas, including fuels and chemical feedstock production. Furthermore, UCG also offers a high potential for integration with Carbon Capture and Storage (CCS) to mitigate greenhouse gas emissions. In the present study, a stoichiometric equilibrium model, based on minimization of the Gibbs function has been used to estimate the equilibrium composition of the synthesis gas. Thereto, we further developed and applied a proven thermodynamic equilibrium model to simulate the relevant thermochemical coal conversion processes (pyrolysis and gasification). Our modeling approach has been validated against thermodynamic models, laboratory gasification experiments and UCG field trial data reported in the literature. The synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas quality resulting from UCG, considering varying coal and oxidizer compositions at deposit-specific pressures and temperatures.

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Prediction of feasible synthesis gas compositions at three European coal deposits

10.5194/egusphere-egu21-2328 ◽

2021 ◽

Author(s):

Christopher Otto ◽

Thomas Kempka

Keyword(s):

Synthesis Gas ◽

Coal Gasification ◽

Economic Feasibility ◽

Gas Composition ◽

Underground Coal Gasification ◽

Computationally Efficient ◽

Coal Conversion ◽

Coal Deposits ◽

In Situ Conditions

In the present study, we apply our validated stoichiometric equilibrium model [1], based on direct minimisation of Gibbs free energy, to predict the synthesis gas compositions produced by in-situ coal conversion at three European coal deposits. The applied modelling approach is computationally efficient and allows to predict synthesis gas compositions and calorific values under various operating and geological boundary conditions, including varying oxidant and coal compositions. Three European coal deposits are assessed, comprising the South Wales Coalfield (United Kingdom), the Upper Silesian Coal Basin (Poland) and the Ruhr District (Germany). The stoichiometric equilibrium models were first validated on the basis of laboratory experiments undertaken at two different operating pressures by [2] and available literature data [3]. Then, the models were adapted to site-specific hydrostatic pressure conditions to enable an extrapolation of the synthesis gas composition to in-situ pressure conditions. Our simulation results demonstrate that changes in the synthesis gas composition follow the expected trends for preferential production of specific gas components at increased pressures, known from the literature, emphasising that a reliable methodology for estimations of synthesis gas compositions for different in-situ conditions has been established. The presented predictive approach can be integrated with techno-economic models [4] to assess the technical and economic feasibility of in-situ coal conversion at selected study areas as well as of biomass and waste to synthesis gas conversion projects.[1] Otto, C.; Kempka, T. Synthesis Gas Composition Prediction for Underground Coal Gasification Using a Thermochemical Equilibrium Modeling Approach. Energies 2020, 13, 1171.[2] Kapusta et al., 2020[3] Kempka et al., 2011[4] Nakaten and Kempka, 2019

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