Energy promise of unminable coal. [Hamma, WY, expts]

Journal Article · Sat Apr 01 04:00:00 EST 1978 · Compressed Air; (United States)

OSTI ID:5358976

Low-Btu gas produced at Hanna consists of 4 to 6 percent methane; 45 to 50 percent nitrogen, because air rather than pure oxygen is injected; 12 to 18 percent carbon monoxide; 15 to 20 percent hydrogen; 10 to 15 percent carbon dioxide; small amounts (less than 1 percent) of ethane and propane; and about 0.1 percent hydrogen sulfide. The combustible gases contained in this mixture are hydrogen, methane, carbon monoxide, ethane, and propane, Nitrogen and carbon dioxide have no heating value and simply dilute the ases produced from underground coal gasification (UCG), thereby yielding the low-Btu gas. Injecting oxygen rather than air would achieve a higher Btu gas; no nitrogen would be produced. Plans to do this at Hanna have been made, but the first-generation process is to develop the system using air. Oxygen injection requires stringent safety precautions and preparation not needed during air injection. One of the most promising aspects of UCG is that it lacks those major environmental impacts associated with current coal mining or coal combustion techniques. Large areas of land are not removed from use for any extended periods of time, and reclamation is not a serious problem because the land surface is not disrupted. There are some other advantages: no sulfur oxides are emitted because the sulfur can be scrubbed from the gas before burning it; less-high-quality water is required because the water in the coal regardless of its quality, is used in the process; and, no large amounts of solid wastes are left above ground, all ash is left in the coal seam. However, there will be some environmental impacts. The areas of major concern are the effects of UCG on groundwater quality and the effects of subsidence. The economic feasibility of UCG is purely speculative at this time.

• OSTI ID: 5358976
• Journal Information: Compressed Air; (United States), Journal Name: Compressed Air; (United States) Vol. 83:4; ISSN COAIB
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
BOREHOLE LINKING
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL GASIFICATION
COMBUSTION
ECONOMICS
FLUIDS
FUEL GAS
FUELS
GAS FUELS
GASES
GASIFICATION
GROUND SUBSIDENCE
GROUND WATER
HYDROGEN COMPOUNDS
IN-SITU GASIFICATION
IN-SITU PROCESSING
LOW BTU GAS
OXIDATION
OXYGEN COMPOUNDS
PROCESSING
REVERSE COMBUSTION
THERMOCHEMICAL PROCESSES
WATER