Competitiveness and Cost Sensitivity Study of Underground Coal Gasification Combined Cycle Using Lignite

Pei, Peng; Barse, Kirtipal; Nasah, Junior

doi:10.1021/acs.energyfuels.6b00019

Cited by 10 publications

(3 citation statements)

References 13 publications

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“…Due to dilution by added nitrogen, the calorific value of the product gas recovered by UCG is 4-12 MJ/m 3 , which is lower than that of natural gas (38-40 MJ/m 3 ). UCG gas can be used to supply electricity through a combined cycle power generation [5][6][7] and to produce raw materials such as hydrogen, ammonia, and methanol [8][9][10]. This technique has the potential to utilize coal resources that remain unrecoverable in the underground due to either technological or economic reasons.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on evaluation of underground coal gasification with a horizontal hole using two different coals

Hamanaka

Itakura

et al. 2021

Fuel

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Section: Introductionmentioning

confidence: 99%

Experimental study on evaluation of underground coal gasification with a horizontal hole using two different coals

Hamanaka

Itakura

et al. 2021

Fuel

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“…Underground Coal Gasification (UCG) can exploit the energy stored in underground coal efficiently and with fewer environmental impacts. Valuable gas products can be obtained by gasifying coal in situ with a UCG operation [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The general UCG system, comprising of an injection well and a production well at the surface, is shown in Figure 1, in which both wells are connected by a linking hole within the coal seam [15,16].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a Compact Coaxial Underground Coal Gasification System Inside an Artificial Coal Seam

Hamanaka

Itakura

et al. 2018

Energies

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The Underground Coal Gasification (UCG) system is a clean technology for obtaining energy from coal. The coaxial UCG system is supposed to be compact and flexible in order to adapt to complicated geological conditions caused by the existence of faults and folds in the ground. In this study, the application of a coaxial UCG system with a horizontal well is discussed, by means of an ex situ model UCG experiment in a large-scale simulated coal seam with dimensions of 550 × 600 × 2740 mm. A horizontal well with a 45-mm diameter and a 2600-mm length was used as an injection/production well. During the experiment, changes in temperature field and product gas compositions were observed when changing the outlet position of the injection pipe. It was found that the UCG reactor is unstable and expands continuously due to fracturing activity caused by coal crack initiation and extension under the influence of thermal stress. Therefore, acoustic emission (AE) is considered an effective tool to monitor fracturing activities and visualize the gasification zone of coal. The results gathered from monitoring of AEs agree with the measured data of temperatures; the source location of AE was detected around the region where temperature increased. The average calorific value of the produced gas was 6.85 MJ/Nm3, and the gasification efficiency, defined as the conversion efficiency of the gasified coal to syngas, was 65.43%, in the whole experimental process. The study results suggest that the recovered coal energy from a coaxial UCG system is comparable to that of a conventional UCG system. Therefore, a coaxial UCG system may be a feasible option to utilize abandoned underground coal resources without mining.

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“…Following the proposal of UCG in the 1910s, more than 100 years of experimentation and practice in UCG ,− have made it one of the most popular methods for coal utilization, especially because of its advantages of being safe, being cost-effective, , and having low environmental impact. The development of CO 2 capture and storage technology − has aroused much research interest in UCG.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Coal Combustion Zone and Gas Energy Recovery for Underground Coal Gasification (UCG) Process

Hamanaka²,

Itakura³

et al. 2016

Energy Fuels

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During underground coal gasification (UCG) operations, evaluation of coal gasification cavity evolution and precise control of the underground reactor are important for efficient gasification. It is also essential to estimate the energy recovery of a UCG system and the whole gasification process to ensure an effective combustion and gasification rate. An experimental simulation of UCG using an artificial coal seam comprising a compacted broken coal block was conducted using ex situ UCG models. The main goal of the experiments was the establishment of evaluation methods for the gasification zone and energy recovery during UCG. To investigate the distribution and extent of fracture activity, and to evaluate the propagation of the combustion area in the UCG reactor, we used acoustic emissions (AE) monitoring. This was combined with traditional measurements of temperature variation and product gas content. This paper presents the results of AE analysis of the fracturing activities and damage mechanisms of the coal seam with respect to the UCG operations. From the results of AE source location, we found that the position and area of the crack concentration area, i.e., the gasification zone, can be inferred with comparative accuracy. This is important for in situ practical application of underground coal gasification. In addition, use of the distribution characteristics of AE information over time can also provide advanced warning, and help in timely adjustment of the operational parameters. The results of gas energy recovery were estimated with a proposed stoichiometric method based on measured product gas composition. Quantitative evaluation results include the gas quantities, coal consumption, and heating value yield of the produced synthesis gas. The coal consumption of the obtained energy recovery results also meets the estimated results when calculating the gasification volume with AE source locations (in an error range of about 10%). Therefore, the applied AE monitoring and gas energy recovery approaches may be considered attractive options for evaluating the coal gasification process and developing a safe and efficient UCG system.

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Competitiveness and Cost Sensitivity Study of Underground Coal Gasification Combined Cycle Using Lignite

Cited by 10 publications

References 13 publications

Experimental study on evaluation of underground coal gasification with a horizontal hole using two different coals

Experimental study on evaluation of underground coal gasification with a horizontal hole using two different coals

Evaluation of a Compact Coaxial Underground Coal Gasification System Inside an Artificial Coal Seam

Evaluation of Coal Combustion Zone and Gas Energy Recovery for Underground Coal Gasification (UCG) Process

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