Advanced Underground Coal Gasification Technology for Efficient Production of Synthetic Gaseous Fuels

The study presents a comprehensive assessment of a novel underground coal gasification technology designed to improve both economic efficiency and environmental performance relative to traditional coal extraction and surface gasification methods. Experiments were conducted using a thermochemical modeling installation, a high-temperature steam generator, and a catalytic conversion unit. Results demonstrated that the process allowed precise regulation of the gas composition by adjusting the oxygen content, temperature, and pressure of the injected medium. Under optimized steam-oxygen injection, the produced syngas achieved a calorific value of up to 10.6 MJ/m³, with hydrogen concentrations exceeding 42%. Subsequent catalytic methanation yielded substitute natural gas with a calorific value of 32.5-34.2 MJ/m³ and a methane content of up to 91%. The gas yield per ton of coal ranged from 1700 to 2300 m³, depending on the coal type. The calculated production cost of the synthetic gas was 52–56 USD per 1000 m³, significantly lower than that of comparable surface technologies. The findings confirm that this approach enables effective in situ conversion of low-grade coal reserves into a valuable gaseous fuel while reducing costs and enhancing energy security.