"A couple of efficient thermal energy generation through the in-situ combustion of coal , and the on-site conversion of that energy to electricity is discussed and shown to offer distinct advantages in the utilization of our coal reserves. Analysis of data from previous underground coal gasification projects indicates that coal can be completely burned underground and that the burning process should be maintainable for time periods sufficient to power an electricity generation plant on a commercial level. A discussion is presented related to the requirements of a 100 Megawatt (thermal) demonstration in-situ combustor, and some of the important problem areas that have to be resolved prior to implementation of the concept."