Underground Coal Gasification Project Research Articles

Mineralization reaction between CO2 and coal ash produced from underground coal gasification: Implication for in situ carbon sequestration

Underground coal gasification (UCG) represents a promising clean and low-carbon energy technology, which could create a suitable cavity for in situ carbon sequestration by mineralization reaction between CO2 and coal ash produced from UCG. This may assist in achieving a net-zero carbon emission goal for UCG projects. To determine the carbonation efficiency and mineralization potential of CO2 mineral sequestration in abandoned UCG cavity, coal ash produced from the gasification of three different low-rank coal samples was used in this study. A comparative experiment was conducted using a group of high-calcium fly ash from a coal-fired power plant. All mineralization reaction experiments were performed in a high-temperature and high-pressure reactor, with CO2 pressures ranging from 2 to 8 MPa and temperatures ranging from 40 to 80°C. These conditions were selected to simulate the sequestration conditions in the UCG cavity. Real-time monitoring of CO2 pressure in the reactor was used to assess the impact of solid-to-water ratio, temperature, and pressure on the CO2 mineralization. X-ray diffraction and scanning electron microscopy were employed to identify the presence of newly formed carbonate minerals associated with mineralization reaction. The results indicated that the coal ash produced by gasification pretreatment at 900°C contains a substantial quantity of alkaline-earth oxides, such as calcium oxide (CaO), with a relative mass fraction reaching 25.9%. It provided an adequate supply of alkali metal ions for the mineralization reaction, which exhibited comparable efficacy in mineralizing CO2 to that observed in high-calcium fly ash. Without stirring, at lower solid-to-water ratio, the maximum amount of CO2 consumed through mineralization was increased by up to 74.12%. Carbonation efficiency decreased with rising temperatures below 70°C due to the limited dissolution of CO2 in water, it increased with elevated pressure but decreased in the supercritical state, potentially attributable to the dissolution of carbonate minerals in a supercritical CO2 environment. The process of mineralization reaction between CO2 and coal ash aligned well with the Surface Coverage Model (R2 values ranging from 0.92 to 0.99). A preliminary estimation based on Chinese coal reserves revealed that the potential of CO2 sequestration capacity in UCG cavities by mineralization ranging from 29 to 102 Gt, an additional 517 Gt CO2 may be stored when filled with fly ash. This paper provides theoretical bases for predicting the maximum carbonation efficiency under high-pressure and high-temperature conditions in UCG cavities, and research directions for achieving a net-zero carbon emission goal for UCG projects.

Characteristic Analysis and Risk Control of Syngas Explosion during Underground Coal Gasification.

Gas explosion is one of the main accident risks during underground coal gasification (UCG). There are significant differences in the gas composition and explosive environment between UCG syngas and other gases. Previous research on the explosion characteristics of UCG syngas is not comprehensive enough, especially without considering the influence of the initial temperature on various characteristic parameters. A set of calculation methods for explosion characteristic parameters of UCG syngas based on existing research was proposed, which was applied to analyze explosion characteristics of syngas produced by different gasifying processes in the Huating UCG industrial test. The results showed that with the initial temperature improving, the maximum temperature and upper explosion limit of different gases increased, while the maximum pressure, lower explosion limit, and oxygen content safety limit decreased. However, the explosion thermal effect, pressure rise rate, and explosion characteristic values showed small changes. When the initial temperature increased from 298 to 1473 K, the explosion temperature of different gas explosions increased from 1645-2286 to 2652-3238 K, the maximum pressure dropped from 0.59-0.81 MPa (absolute pressure) to 0.19-0.23 MPa, the lower explosion limit dropped from 12.34-29.79% to 0.58-1.77%, the upper explosion limit increased from 55.68-83.35% to 70.89-93.73%, and the safety limit of oxygen content dropped from 4.86-6.37% to 0.26-0.34%. In addition, the gas calorific value also affected the values of various explosion characteristic parameters, among which the explosive thermal effect, maximum temperature, maximum pressure, pressure rise rate, explosion characteristic value, and safety limit of oxygen content in the syngas were all proportional to the calorific value of gas, while the lower and upper limits of explosion were inversely proportional to it. Based on the above research, syngas explosion-prone stages and causes of each potential risk area in the Huating UCG project were analyzed, the explosion characteristic parameters were determined, and targeted prevention and control measures were proposed accordingly. This study can lay a theoretical foundation for the study of syngas explosion characteristics and risk control for the UCG project.

Nonlinear-Control-Oriented Modeling of the Multi-Variable Underground Coal Gasification Process for UCG Project Thar: A Machine Learning Perspective

The Underground Coal Gasification (UCG) process is a complex and multi-physics phenomenon, thus making it difficult to develop a mathematical model that encapsulates all dynamical aspects. In this regard, data-driven modeling techniques offer a reliable alternative for prediction, control, and optimization of dynamical systems, but their application in UCG is still in the early stages. This work aims to bridge this gap by implementing three cutting-edge nonlinear identification structures: Non-linear Autoregressive with Exogenous Inputs (NARX), Hammerstein–Wiener (HW), and State-Space Neural Networks (SSNN) on the UCG process to obtain a multivariable control-oriented model. The contributions include synthesizing an excitation signal for data acquisition, outlining the non-linear system identification procedure, and comparing predictive capabilities using statistical tools. The simulation results demonstrate a rigorous comparison of various techniques for the heating value and flowrate of the syngas, which are the outputs of the UCG process. The results of the analysis show that NARX outperforms other structures in statistical metrics, with MAE, RMSE, and Best fit values of 1.51,1.9, and 0.9, respectively, for the heating value; and 0.25,0.31, and 0.94, respectively, for the flowrate. Consequently, the outputs of the NARX model are compared with the experimental data obtained from the UCG project Thar, which show a good match for both outputs.

Direct tensile mechanical properties and damage fracture mechanisms of thermally damaged coal measures sandstone under high strain rate loading

The direct tensile mechanical properties of highly thermally damaged rock under high strain rate loads are a key basic mechanical problem that must be solved for the stability and effective control of surrounding rock stability in the combustion control area of an underground coal gasification project. In this paper, a two-dimensional equivalent grain-based model (GBM) unit and Split Hopkinson Tension Bar (SHTB) numerical model for thermally damaged coal-measures sandstone were constructed using particle flow code (PFC). The comparison with the experimental results shows that the numerical method can accurately describe the dynamic direct tensile behavior of thermally damaged sandstone. The following conclusions are drawn: The dynamic tensile strength of thermally damaged sandstone shows a significant strain rate-strengthening effect. With the increase in thermal damage temperature, the dynamic tensile strength of sandstone increases first and then decreases. The generation and development of hot cracks in a high-temperature environment is the fundamental reason for the change in macroscopic mechanical properties. The dynamic tensile failure process of thermally damaged sandstone can be divided into four stages: the dynamic damage initiation, the dynamic damage development, the damage crack penetration, and the sample dynamic fracture. With the increase in impact velocity, the initial kinetic energy, elastic strain energy, dissipated energy, and elastic strain energy ratio in the failure process of thermally damaged sandstone gradually increase. In contrast, the dissipated energy ratio gradually decreases. As the heat treatment temperature increases, the elastic strain energy and the ratio of elastic strain energy increase first and then decrease.

Dynamic tensile mechanical properties of thermally damaged sandstone under impact loads and the influence mechanism of composition

The stability of surrounding rock in the combustion void is the key to continuous, safe, and efficient gas production in an underground coal gasification project. The key factors influencing the stability of surrounding rock in the combustion void are high temperature and impact dynamic load. At the same time, rock structure failure mainly depends on the rock materials’ tensile strength. Therefore, it is fundamental to study the dynamic tensile mechanical properties of thermally damaged rocks to control the surrounding rock stability of the combustion void in UCG projects. This paper used the coal measures as the research object. The dynamic direct tensile test of thermally damaged sandstone was carried out using a high-temperature load system and split Hopkinson tension bar (SHTB) test system. The test results showed that the dynamic tensile strength of sandstone increased linearly with the increase in strain rate. In contrast, it increased first and then decreased with temperature. In addition, the nonlinear regression method was applied to establish the prediction model of dynamic tensile properties of thermally damaged sandstone. XRD analyzed the composition and mass fractions of sandstone. From the standpoint of composition change, the change mechanism of the mechanical properties of thermally damaged coal measured in sandstone was illustrated.

A Thermal-Hydrological-Mechanical-Chemical Coupled Mathematical Model for Underground Coal Gasification with Random Fractures

In this paper, in order to understand the development process and influencing factors of coal underground gasification, taking the two-dimensional underground gasification area of the plane as the simulation object, the characteristics of the multi-physical field coupling process of exudate mass heat transfer and combustion gasification reaction in the process of horizontal coal seam underground gasification are analyzed, and a two-dimensional mathematical model of thermal-hydrological-mechanical-chemical coupling of a porous medium is established. The temperature distribution of coal rock from the gasification point, the distribution of gas water vapor pressure and stress-strain, the temperature contour distribution of fractured coal rocks of different densities of heterogeneity, and the influence of different water-oxygen ratios and different fractured coal rocks on the gas components generated by the gasification reaction were studied. The results show that the tensile damage caused by the tensile strain volume expansion of the coal underground gasification center, the shear damage caused by the compression of the edge compressive strain volume, and the temperature conduction rate decrease with the increase in the coal rock fracture, but in the heterogeneous coal rock, the greater the fracture density, the faster the temperature conduction rate, which has a certain impact on the gasification combustion reaction. The ratio of CO2, H2 and CO in the case of simulating that the water-to-oxygen ratio is 1:2, 1:1, and 2:1 is 1:0.85:0.73, 1:1.1:0.97, and 1:1.76:1.33, respectively. At a water-oxygen ratio of 2:1, the concentration ratio is the most ideal, and the main gases, CO, CO2, and H2, are 32%, 21%, and 37%. Furthermore, the reaction rate increases with the increase of fracture density. The gas component concentration simulated in this paper has good consistency with the results of the previous experimental data, which has important guiding significance for the underground coal gasification project.

Numerical study of ground deformation during underground coal gasification through coupled flow-geomechanical modelling

This paper presents a coupled flow-geomechanical model to study the ground deformation due to geoenergy applications involving complex thermo-hydraulic-chemical–mechanical coupled processes, such as underground coal gasification (UCG). The model is developed by coupling two sub-models, that is, the chemical reactions associated flow model that can predict temperature development and cavity growth and the geomechanical model that considers the temperature-dependent thermo-mechanical properties of geologic materials and the conversion of coal to the cavity. Numerical simulations of a field-scale UCG project with the linked vertical wells (LVW) were conducted through coupled flow-geomechanical modelling. The effects of the thermo-mechanical properties of the strata adjacent to the coal seam and the UCG operational conditions on the temperature distribution, cavity formation, and ground deformation in the operating stage of UCG were studied. Simulated results showed that temperature of over 1200 K would be obtained between the injection well and the production well in the coal seam while the 400 K isotherm only moved less than 2 m vertically in the strata near the UCG reactor. Cavity with long forward length and short backward length was formed between the injection well and the production well. Ground deformation during UCG was caused due to the combined effects of temperature and cavity evolution. The parametric sensitivity study showed that when the initial elastic modulus of the surrounding strata decreased from 4 GPa to 1 GPa, its effect on the ground deformation beyond the right side of the production well was not of significance. The ground deformation was not sensitive when the initial thermal expansion coefficient of the surrounding strata was reduced to the order of magnitude of 1.0-6 (K−1). In addition, adjusting the supply rate of O2 and modifying the location of the horizontal gasification channel can control the ground deformation during UCG. The coupled flow-geomechanical model presented in this paper can be helpful in the safety control of UCG.

Residual coal distribution in China and adaptability evaluation of its resource conditions to underground coal gasification

This paper researched the distribution and the characteristics of residual coal resources for their adaptability into underground coal gasification (UCG) technology to promote a potential green technology for the development of residual coal resources in China. The results reflected that the average recovery rate of resources for coal mines was only 37.67% in China, and the residual coal reserves reached 148.53 gigatons (Gt), of which 52.51% occurred in North China. Furthermore, these resources are mainly distributed in the buried depth shallower than 800 m, accounting for 87.15%. And residual coal types were primarily bituminite with a percentage of 72.89%. We established a multi-level model with membership functions that included an analytic hierarchy and a fuzzy comprehensive evaluation with variable weight theory. As a result, a varying weight fuzzy hierarchical evaluation model for the resource conditions feasibility of residual coal with UCG technology was established. Finally, the model was applied to the resource condition feasibility evaluation of UCG industrial tests at Zhongliangshan, Huating, and Shanjiaoshu Mines. The industrial tests showed that the evaluation model constructed in this paper could comprehensively, objectively, and intuitively reflect the adaptability of residual coal resources to UCG technology, providing a scientific reference for UCG project decision-making.

Business analysis of implementation of UCG technology in Indonesia

There is a deep-seated coal potency with a depth more than 100 meters below surface in Indonesia that has not been exploited yet. Underground Coal Gasification (UCG) is an unconventional technology that can become the solution to exploit the deep-seated coal potential by extracting coal into in-situ gas that can be converted to electricity or chemicals. Based on business analysis, this paper aims to analyze the implementation of UCG technology in Indonesia, whether it is potential or not. Data are collected from literature and analyzed using Porter Five Forces and PESTLE Analysis. The Porter Five Forces analysis shows that the implementation of UCG in Indonesia is still potential as an industry because the only threat will come from substitute products. PESTLE analysis shows that almost all the factors, except for technology, are very supportive of implementing UCG commercial plants in Indonesia. Based on both studies, it can be concluded that the UCG project is very potential to be developed in Indonesia. However, it needs full support and control from the government because it will become a pioneer project with financial and environmental risk still has not quantified ideally.

Advantages of underground coal gasification implementation in Indonesia

Underground Coal Gasification (UCG) is an energy manufacturing process whereby coal is gasified or chemically converted into a gas, in-situ. UCG has several benefits in terms of low capital cost, lower environmental impact, high energy density and long-term production certaint y. The objective of this study is to describe the advantages of implementing UCG technology in Indonesia based on UCG gas resources, product market, coal quality and availability of regulation to support UCG projects. UCG gas resources are estimated based on data of CBM resource and coal quality was examined by heat treatment. The size of conservatively estimated potential UCG gas manufacturing volume in Indonesia based on CBM data is 160 TCF which is greater than Indonesia’s natural gas reserves, namely 142.7 TCF. UCG gas markets are available in South Sumatera and East Kalimantan since the natural gas production in the two provinces is declining significantly. UCG in Indonesia is regulated under the mineral and coal regulatory regime, which brings some benefits, including more flexibility in the type of drilling rigs that can be used for UCG, compared to oil and gas drilling.

Environmental assessment of underground coal gasification in deep-buried seams

This study presents a preliminary assessment of the environmental impact of field-scale underground coal gasification (UCG) targeting deep-buried seams by studying the fate of the UCG products in the reactor vicinity. A series of simulation scenarios are conducted in three deep (900 m) areas of specific interest – namely, South Wales coalfield (UK), Upper Silesian coal basin (Poland) and Ruhr mining district (Germany) – to investigate the transport of gaseous and dissolved chemicals. The results indicate that the syngas propagation is limited to 2.0 m in the vicinity of the reactor after 30 days, except that it is limited to 4.4 m in shale (overburden) of the UK site. Transport of the dissolved chemicals, through diffusion, is limited to 2.0 m without considering adsorption and less than 0.5 m when adsorption is considered after 10 years. Moreover, the effects of hydrology condition, stratum adsorption properties and the thermally induced change in rock porosity and permeability on the propagation of UCG products are studied. The results suggest that unacceptable risks to the environment are unlikely to arise if standard operating conditions are applied, offering a great prospect of deep coal seams to be considered for UCG. This study also provides insights into the environmental evaluation for other potential UCG projects.

Mechanical performance evolution and size determination of strip coal pillars with an account of thermo-mechanical coupling in underground coal gasification

In this study, underground coal gasification (UCG) technology with the strip mining method was recommended to avoid the instability of surrounding rock in the UCG cavity and possible groundwater pollution, in which mechanical performance and reasonable size of the strip pillar play the crucial role. The respective innovative calculation method considering the thermo-mechanical coupling effect was proposed and applied to size designs of pillars in the UCG projects of the Shanjiaoshu Mine and Mazino coal deposit. The proposed method feasibility was experimentally validated and yielded the following predictions of the coal pillar mechanical performance evolution during the UCG process. Heat-affected zones in the coal pillar and immediate roof gradually increased with the following decline. High temperatures above 250 °C affected the coal and rock masses only at a distance not exceeding 2 m from the surface, but their effect continued even after the UCG termination. High temperatures reduced the load-bearing capacity in the area near the coal pillar surface and induced long-term thermal stresses in coal pillars, which alternatively played a dominant role in affecting the ultimate strength of the coal pillar at different stages. The plastic zone width xp in the pillar is varied and will remain unchanged once it reaches its peak value. The width of strip pillars Wp is greatly influenced by high temperatures; it exhibits a W-shaped variation pattern during the UCG process and slowly drops after gasification. The strip pillar width of UCG can be determined using the maximum value of function Wp(t) considering a certain safety factor. While the wide pillar's total strength and size are slightly affected by the temperature, its width can be obtained from Wp(0) with a safety factor. This study can be used for predicting the mechanical performance evolution and size determination of pillars in the UCG process.

Data-Driven Modeling and Design of Multivariable Dynamic Sliding Mode Control for the Underground Coal Gasification Project Thar

The energy output per unit time is an important performance metric to determine the potential of an underground coal gasification (UCG) site for electricity production. The energy output per unit time is a function of heating value and flow rate of syngas, and therefore, it is essential to devise a multivariable closed-loop system to enhance the efficiency of the UCG process. In this work, a model-based, multivariable dynamic sliding mode control (DSMC) has been designed for the cavity simulation model (CAVSIM), parameterized with the operating parameters and coal properties of the UCG Project Thar (UPT) field. The model-based control of CAVSIM is not possible due to its complex and multidimensional dynamics, and thus, a simple linear multivariable model is identified by employing a subspace (N4SID) system identification technique. The regular form of the linear model is formulated to design the model-based DSMC. Moreover, the stability of zero dynamics is shown on the approximate model of CAVSIM. Consequently, the designed controller is implemented on CAVSIM, and simulation results are compared with conventional sliding mode control (SMC). It has been observed that both the controllers have achieved the tracking objectives in the presence of input disturbance and modeling uncertainties. However, DSMC utilizes lesser control energy to achieve the desired objectives. Furthermore, the continuous control inputs in DSMC significantly reduce chattering.

Evolution of permeability and microscopic pore structure of sandstone and its weakening mechanism under coupled thermo-hydro-mechanical environment subjected to real-time high temperature

Thermal damage mechanisms and the characteristics of performance deterioration of a repository host rock is critical for evaluating the potential of an underground coal gasification project. Previously, many studies have primarily focused on the microstructural evolution of various rock types after high-temperature treatment only. However, relatively little is known regarding the coupled thermo-hydro-mechanical (THM) behavior of rock, which is frequently encountered in geo-engineering underground regions with high-temperatures. In this study, using a self-developed universal tester with the ability of THM coupling of high temperature and high pressure, permeability evolution in sandstone under real-time high temperature (20–700 °C) and triaxial stress (hydrostatic pressure = 25 MPa) were observed. The microphysical parameters of these specimens subjected to the THM environment were then measured, and the corresponding morphological evolution processes were also assessed using micro-computed tomography (MCT). Further, for the purpose of contrast, we have also determined the microphysical parameters for the sandstone after heat treatment only. The results show that the evolution of the microscopic structures within the sandstone under the coupled THM condition is vastly different from those subjected to heat treatment only. The experimental results in this study can provide theoretical guidance for the stability of surrounding rock of a combustion cavity during in-situ coal gasification.

Design and implementation of multi-variable [formula omitted] robust control for the underground coal gasification project Thar

The energy per unit time is an important performance indicator in determining the performance of an underground coal gasification (UCG) site to produce electricity. In literature, model-based strategies are employed by considering UCG as a single input single output (SISO) system, in which only the heating value of syngas is maintained at the desired level by varying inlet gas flow rate. However, the energy per unit time is also dependent on the flow rate of the produced gas mixture. Therefore, in this work, a model-based multi-variable robust control design, based on H∞ technique is proposed for the UCG process. The actual nonlinear model of UCG is very complex due to its 3D axisymmetric geometry, which makes the model-based control design a formidable task. Thus, a simple linear model with two inputs (flow rate and composition of inlet gas) and two outputs (flow rate and heating value of syngas) is identified by using subspace-based (N4SID) system identification technique. The linear model is then employed to design the H∞ (S/KS mixed sensitivity) multi-variable robust controller. The simulation results show that the designed controller has achieved both robust stability and performance in the presence of modeling inaccuracies and external disturbance. Furthermore, the designed controller is also implemented on the actual nonlinear cavity simulator (CAVSIM) for the UCG process. The controller exhibits an adequate performance by tracking the desired set points for the heating value and flow rate of the syngas.

Biodegradation of BTEX by indigenous microorganisms isolated from UCG project area, South Sumatra

Recently Indonesia is conducting Underground Coal Gasification (UCG) project in South Sumatra for power generation.The potential of negative impacts from UCG on groundwater and the broader environment can not be ignored since past similar projects were often confronted with pollution isues of BTEX and PAHs due to condensation of tar-loaded gas. This study focuses on finding indigenous microorganisms capable of BTEX degradation and evaluate their biodegradability. Several microorganisms were successfully isolated and screened. Pseudomonas putida and Bacillus cereus were chosen for this bioremediation study since the bacteria were predominant and highly viable on the screening test. The BTEX degradation has been studied in single component using single and mixed bacterial cultures in the concentration range of 250-500 ppm. The experimental results show that biodegradation of BTEX by P. putida ranged from 61.4-70.2% and by B.cereus ranging 63.9-74.7 % at initial BTEX concentration of 500 ppm.Meanwhile, consortium of both isolates has the highest percentage of BTEX biodegradation (67.8-79,8%) during 14 days of retention time.The findings reveal that indigenous bacteria of P. putida dan B. cereus exhibit the potential to be used for decontamination of BTEX as an anticipated mitigation for potential pollution coming from the UCG project.

Prediction and parametric analysis of cavity growth for the underground coal gasification project Thar

Underground coal gasification (UCG) is a promising clean coal technology to convert unmineable and deep coal reserves into syngas, which can be used in many industrial applications. In UCG field, real time monitoring of hydrological and geological conditions such as water influx rate, cavity growth and its interaction with overburden is a formidable task. UCG project Thar (UPT) lacks real time data acquisition system to monitor these parameters. In this work, a 3D axisymmetric cavity simulation model (CAVSIM) is parameterized with operating conditions of UPT and properties of Lignite B coal of Thar coal fields. For model validation, a comparison has been made between simulated and the UPT field data for the composition and heating value of syngas. The results of CAVSIM are also compared with our previous ID packed bed model, which show the superiority of CAVSIM model. Moreover, a comprehensive simulation study has been carried out to predict the cavity growth and its interaction with overburden. The effect of operating parameters of UPT on volumetric cavity growth and heating value of syngas are also investigated.

Monitoring and Control in Underground Coal Gasification: Current Research Status and Future Perspective

By igniting in the coal seam and injecting gas agent, underground coal gasification (UCG) causes coal to undergo thermochemical reactions in situ and, thus, to be gasified into syngas for power generation, hydrogen production, and storage. Compared with traditional mining technology, UCG has the potential sustainable advantages in energy, environment, and the economy. The paper reviewed the development of UCG projects around the world and points out that UCG faces difficulties in the field of monitoring and control in UCG. It is expounded for the current research status of monitoring and control in UCG, and clarified that monitoring and control in UCG is not perfect, remaining in the stage of exploration. To improve the problem of low coal gasification rate and gas production, and then to make full use of the potential sustainable advantages, the paper offers a perception platform of a UCG monitoring system based on the Internet-of-Things (IoT) and an optimal control model for UCG based on deep learning, and has an outlook on breakthrough directions of the key technologies related to the package structure design for moisture-proof and thermal insulation, antenna design, the strategy for energy management optimization, feature extraction and classification design for the network model, network structure design, network learning augmentation, and the control of the network model, respectively.

A preliminary study of Indonesian coal basins for underground coal gasification development

The energy needs in Indonesia are continuing to increase, however, the production of oil and gas declines. This problem can be minimized by developing alternativ e energy such as underground coal gasification (UCG) by utilizing deep seated coal at 200 to 1 . 000 m below surface . The objective of this study is to evaluate coal characteristic in the basins for UCG purpose depends on several coal properties such as its rank (below bituminous), thickness (5m), depth (up to 200m), and ash content plus total moisture (below 60%). Based on coal analysis of 11 coal basins from previous exploration drilling, there were several coal layers in four selected basins to be applied for the UCG project, namely 7 coal layers in South Sumatra Basin , 7 coal layers in Barito Basin , 2 coal layers in Asam- a sam Basin and 5 coal layers in Kutai Basin . Based on the SNI No. 5015-2011, the coal resources was calculated and converted into a gas by a simulation procedure. Total UCG coal in South Sumatera Basin is 80 1 million tons , meanwhile, the Barito Basin has 436 million tons, Asam-asam 136 million tons, and Kutai 289.7 million tons. The total hypothetical syngas is 8.38 TSCF. The UCG facilities in South Sumatra Basin should be designed to produce the syngas as the natural gas within this area is in deficit condition and the basic cost for electricity supply belongs to low situation, however, the UCG plants in Kalimantan should produce electricity as its cost ratio of electricity is high and this area retains surplus natural gas supply.

Study on environmental quality and hazard identification of underground coal gasification project: A literature study and field survey

Underground coal gasification (UCG) is a procedure to extract synthesis gas (syngas) from the insitu underground coal seams that could not be extracted by conventional mining methods. This is a clean technology as an alternative method for direct insitu coal conversion. This process involves some heavy equipment and complex operation. Hazards identification and risk assessment in the UCG Project involve identifying the environmental hazards that cover physical, chemical and biological environments to predict the process sequences, its frequency as well as consequences that lead to those hazards. The assignment of risk level is also conducted to design corrective action in minimizing the risk or eliminating the hazards. The environmental condition of the project plan is generally good with the fulfillment of the established environmental quality standards.