Lignite resources in Texas

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Kaiser, W. R.

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University of Texas at Austin. Bureau of Economic Geology


Texas lignite occurs in three Eocene (lower Tertiary) geologic units--the Wilcox Group, Jackson Group, and Yegua Formation--and in three ancient depositional systems--fluvial, deltaic, and strandplain/lagoonal. Near-surface resources in Texas at depths between 20 and 200 ft (6.1 and 61 m) in seams 3 ft (0.9 m) or thicker are 23,377 million short tons (21,208 million metric tons) and are dominantly fluvial in origin. More than 90 percent of the resources occur in the Wilcox and Jackson Groups north of the Colorado River. The size of individual deposits ranges from 50 to 500 million tons (45 to 450 million metric tons). The average seam thickness is less than 5 ft (1.5 m); a 10-ft (3.0-m) seam is exceptional. Depending on mining depth, reserves are estimated to be 8,635 to 11,102 million tons (7,834 to 10,072 million metric tons). Deep-basin resources at depths between 200 and 2,000 ft (61 and 610 m) in seams 5 ft (1.5 m) or thicker are 34,819 million tons (31,588 million metric tons), 70 and 30 percent being in the Wilcox and Jackson Groups, respectively. Approximately 2.4 million acres (1.0 million ha) are leased for lignite; 84, 12, and 4 percent of the acreage is in the Wilcox, Jackson, and Yegua, respectively. Wilcox lignite is the best grade, Yegua is intermediate, and Jackson is the poorest grade lignite in Texas. Typical Wilcox lignite has a heating value of 6,500 Btu/lb (3,612 kcal/kg) and a 33-percent moisture, 1-percent sulfur, and 15-percent ash content. Lignite reserves are adequate to meet the projected needs (6 to 7 billion short tons [5.4 to 6.3 billion metric tons]) of the electric utility and industrial sectors into the next century. Most of the lignite will continue to be used to generate electric power; however, lignite will be used in the future to produce synthetic fuels and chemicals.


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