Energy Recovery from In Situ Coal Gasification

Abstract

Estimates of the energy balance for the first underground coal-gasification experiment at Hanna, Wyoming, have been calculated for a 5t-month period from mid-September 1973 through February 1974. Operating results were the most favorable during this period, with d7 gas production rates averaging 1.6 million scf/day (45,300 Nm /day) at an average gas heating value of 126 Btu/scf (1122 kcal/Nm"), The ratio of energy produced to energy consumed in running the experiment was approximately 4, and the overall efficiency was approximately 50%. Use of more efficient air compression equipment and of a system designed for com bustion of low-Btu gas could increase this ratio to 8 and efficiency to 55%. IntroductionIncreasing the portion of our energy supply derived from coal has recently received high priority because of the ever-present threat of loss of our imported oil supplies. A far-reaching government-sponsored coal research program has been in effect for the past few years and is now yielding the technology needed to utilize more fully our vast coal resources. This research program has encompassed a broad range of study, from improved mining methods to removal of sulfur from coal prior to combustion and to development of the technology The authors are with the