UCG industrialization in the Soviet Union: History and comments

China's energy resources are originally poor in oil and gas but rich in coal. The industrialization of underground coal gasification (UCG) technologies, which is an important way of achieving a low-carbon and efficient coal energy structure in China, contributes to the smooth achievement of the peak carbon dioxide emissions and carbon neutrality in China. This study reviews the history of the field tests and industrialization of UCG technologies in the Soviet Union by systematically referencing and sorting literature, aiming to provide a reference for the present development and industrialization of UCG technologies in China. The results show that the development and industrialization of UCG technologies in the Soviet Union lasted for over a hundred years. As the global inventor of UCG technologies and the only country that achieved commercial UCG production, the Soviet Union left a precious and original heritage of UCG processes and technologies to the world. This country first proposed the concept of UCG and the first draft of the UCG gasifier structure, making fundamental contributions to the development of global UCG technologies. Furthermore, the Soviet Union invented technologies like the gas flow method, vertical-well thermal penetration, and horizontal-well long channels in coal seams and initiated the joint mine-drilling UCG process and the oxygen/steam injection UCG process. It also conducted field tests of different gasification processes of coal seams with different geological conditions and set a historical record of more than 50 years of continuous commercial production of a single UCG station, demonstrating the feasibility and strategic value of the commercial application of UCG technologies. Commercial UCG production in the Soviet Union was achieved primarily by raising UCG industrialization to the national strategic level, making the R & D (research and development) of UCG technologies a priority, and attaching great importance to the coordinated promotion of government, industry, universities, research, and applications. By referencing previous experience, UCG industrialization, as a potential technological approach to counteract the insufficient self-supply of natural gas in China and achieve the peak carbon dioxide emissions and carbon neutrality of the country, should be vigorously promoted from the national strategic level. Moreover, the scientific and technological UCG innovation should hold a more important position in the national science and technology planning system, and the construction of the UCG training system for professional technical personnel is the primary foundation for achieving the UCG strategic objectives. In addition, the Soviet Union’s ideas of conducting the UCG technology R&D focusing on two cores—the enhancement of coal seam permeability and gasification control—should be used as a reference. However, improving the gasification and energy recovery of coals by constructing effective gasification channels is still a primary development direction of UCG technologies presently.