Research advances on the techno-economic evaluation of UCG projects

Underground coal gasification (UCG) is driven by China's development strategy for a clean and efficient coal energy structure. Its industrialization prospect depends on the economic and social benefits of UCG projects. Against this background, this study reviews the research advances on the economic evaluation of UCG projects at home and abroad and summarizes the current insights into the economic competitiveness of UCG projects. Through case analysis, it presents a basic model for the economic evaluation of the UCG-combined-cycle gas turbine (CCGT) - carbon capture and storage (UCG-CCGT-CCS) system and the main understanding of the model. Furthermore, this study discusses the insights into the directions for deepening research on the economic evaluation of UCG projects. The results of this study are as follows: (1) There exist differences in the understanding of UCG economics at home and abroad. Generally, researchers are optimistic about the commercial competitiveness of shallow UCG projects but have divergent views on the economics of deep UCG projects. (2) The combination of the basic financial analysis methods with techno-economic parameters and adaptive mathematical tools forms a techno-economic evaluation model of UCG projects. Moreover, the techno-economic studies on UCG at home and abroad show unique characteristics. (3) The economics of UCG projects depends largely on the utilization way of syngas and the method and cost of CO₂ treatment. The total cost of power generation from syngas is influenced the most by factors such as the ratio of coal seam thickness to UCG cavity width (TWR), syngas composition, power generation efficiency, and CO₂ treatment. The following conclusions can be drawn through analysis: (1) To deepen the economic evaluation of China's UCG projects, there is an urgent need to strengthen targeted research on techno-economic parameters, and an objective approach to breaking the current dilemma of understanding differences is to systematically analyze the economics of existing UCG field test cases. (2) In-depth research on the UCG - carbon cycling utilization (CCU) process and its engineering behavior may provide a basis for R&D (research and development) of low-cost CO₂ treatment technologies. (3) The fundamental way to improve UCG efficiency is to innovatively develop UCG technologies and transform constraints into benefit-oriented ones.