Underground coal gasification (UCG) is an important technique for future coal utilization. It has the potential to be a clean technology and to tap un-mineable, deep coal deposits across the world. Commercialization of UCG has been riddled with a variety of issues, including public perception and a lack of clear comprehension about underlying physicochemical phenomena. This book will bridge the gap in knowledge and highlight the modern findings related to the complex interactions in UCG. With a focus on the chemical reactions in UCG and treating the underground coal cavity as “nature’s own chemical reactor”, various mathematical modeling studies that serve to unravel some of the mysteries of this decades-old technique will be revealed.

This report summarizes recent progress on a DOE-supported program to construct computer models for potential future combined coal gasification/fuel cell power generation systems. The approach is to develop physically well-founded descriptions for the performance of both molten carbonate fuel cells and coal gasifiers, and to utilize the models to prepare performance maps for each device, enabling selection of the optimum interfaces between fuel cells and gasifiers. In a previous phase of the study, we identified entrained flow gasification as the most appropriate type for providing fuel cell feed gas, on the basis of off-gas composition and the ability to handle a wide range of coal types. Accordingly, a substantial portion of the current effort is concerned with the development of a computer model for entrained flow gasifiers. Furthermore, several scaling laws have been developed for fuel cell performance. Mostly based on equilibrium (open-circuit) considerations to date, these address such issues as the requirements for avoiding carbon deposition, the potential effects of methane conversion, and the distribution of heat sources and sinks within the cell.