Underground Coal Gasification - A Status Report
Authors: Schrider L.A. , Whieldon C.E. 
Published: December 2007

Underground gasification provides a unique means for recovering energy from coal without mining it. ERDA is conducting several field demonstration projects to test the feasibility of in-situ coal gasification. Several projects to test the feasibility of in-situ coal gasification. Several concepts being tested are discussed.

Introduction
Until recently, the U.S. used its energy resources as if they were inexhaustible. The need for concern over depletion of these resources seemed far in the future. The future, however, has now become the present and the days of plentiful supplies of inexpensive energy have passed. Unfamiliar peacetime terms - fuel shortage, passed. Unfamiliar peacetime terms - fuel shortage, energy crisis, resource allocation, rationing - have become familiar to nearly everyone. Any breakdown in our national energy supply is a major crisis. Past progress in America - in employment, standard of living, welfare of society - largely resulted from the abundant supplies of cheap energy that were available. Without sufficient energy resources, the nation's international and domestic well-being will be affected adversely, resulting in greater material and manpower costs to maintain our standard of living.
The role of oil and natural gas as sources of energy is almost as well known as the shortage of these vital fuels. More than three-fourths of the energy used in the U.S. during 1975 was derived from these sources while coal, the most abundant fossil fuel, supplied less than 20 percent of the nation's energy needs. percent of the nation's energy needs. Because of the vast U.S. coal reserves available, coal became the subject of many studies to increase its use in the total energy mix. Research in coal gasification is increasing because of the shortage of natural gas and the accelerating demand for this valuable, clean energy form. However, most of the conversion work is being done in mined coal, retorted above ground, using various methods. These techniques convert the coal to a gas that, through methanation, can be used as a substitute for high-Btu gas. Substitution of low-Btu gas for natural gas, particularly by the industrial sector, offers further particularly by the industrial sector, offers further augmentation of the natural gas supply. This low-heating value gas can be produced from coal, either above ground or in place. The latter method would, of course, eliminate the need to mine the coal before combustion. While the technology for recovering this energy has been developing for more than 40 years, it has not been adopted commercially in the free world. Many reasons existed for this lack of acceptance. However, most of them have been overcome in the past 3 years.
The ERDA program to develop in-situ coal conversion technology is based on field tests, with a rigorous laboratory and analytical support program. The field demonstration projects are directed toward testing several in-situ gasification concepts in different coal resources in the U. S., including both eastern and western coals. These testing programs provide unique problems depending on the coal resource and its surrounding geology.
Along with ERDA, several universities and private companies will soon be conducting field pilot projects to test further the feasibility of in-situ coal gasification. Seven projects, to be continued or started in the U.S. and Canada, were announced for 1977. Countries such as Belgium, Germany, Austria, and Australia also have indicated that they will initiate in-situ coal programs. With this increased activity, it appears that several candidate concepts show promise for advancing the technology to the commercial stage.
JPT
P. 1179