3. 1997 Demonstrated Reserve Base
and Estimated Recoverable Reserves

Demonstrated Reserve Base (Continued)

Accessibility factors represent the fraction of the DRB--surface or underground--that is presently considered accessible for future development. They are usually determined by measuring or estimating the areas or tonnages of inaccessible coal resources in a study area.

Accessibility adjustments are also recognized as a useful intermediate level at which to make and document internal adjustments that account for variations from standard DRB criteria due to local mining practice. (For example, in Chapter 2, the exclusion of 42-inch or thinner beds from underground mining in Illinois.)

EIA's accessibility factors are closely comparable with U.S. Geological Survey (USGS) Coal Availability Study data.

Recovery factors (Table 13) follow the same format as accessibility factors and are based on recent coal recovery rates for coal mining reported to EIA by mine operators. These may be supplemented by coal field interviews and observations.

The estimated recoverable reserves of coal in the United States(Table B2) represent the estimated portion of the DRB, allocated by Btu and sulfur ranges, that can be recovered by standard mining technologies, assuming a market and an adequate selling price at the time of mining. These reserves are summarized by low-, medium-, and high-sulfur levels in Table 14.

The 1997 estimated recoverable reserves are 1.2 billion short tons larger than estimated for 1995. The 1995 estimated recoverable reserves, in turn, had increased by 9.2 billion short tons, or 3.4 percent, over the previous recoverable reserve estimates, for 1992.⁽²⁾ At 36 percent, low-sulfur estimated recoverable reserves make up the largest part of the total. Medium-sulfur reserves account for 31 percent and high-sulfur reserves for 33 percent.

Based on current mining trends,  however, much of the 64 percent of recoverable coal reserves containing medium and high sulfur levels may not soon be mined because of unfavorable quality, prices, mining costs, location, and/or transportation infrastructure.
 

Table 13. Net Accessibility and Recovery Factors for Coal Resources, by Coal-Producing Region
Coal-Producing Region State	Accessibility Factor		Recovery Factor
	Surface	Underground	Surface	Underground
Appalachia
Alabama	83	90	86	56
Georgia	85	90	80	50
Kentucky, Eastern	71	91	79	62
Maryland	85	90	80	61
North Carolina	85	90	80	50
Ohio	82	88	80	50
Pennsylvania, Anthracite	14	18	90	50
Pennsylvania, Bituminous	85	90	82	59
Tennessee	85	90	80	61
Virginia	80	90	80	62
West Virginia, Northern	75	90	79	59
West Virginia, Southern	82	90	79	59
Interior
Arkansas	85	90	82	52
Illinois	80	64	76	50
Indiana	71	80	82	52
Iowa	85	90	82	52
Kansas	85	90	82	60
Kentucky, Western	75	80	83	53
Louisiana	90	90	82	60
Michigan	85	90	80	50
Missouri	85	90	82	52
Oklahoma	85	90	82	52
Texas	90	90	86	60
Western
Alaska, Northern	50	50	00	00
Alaska, Southern	90	90	88	56
Arizona	90	90	88	56
Colorado	89	90	88	58
Idaho	86	90	80	50
Montana, Eastern	86	90	91	56
Montana, Western	90	90	91	56
New Mexico	90	90	88	56
North Dakota	85	90	90	50
Oregon	90	90	80	50
South Dakota	84	90	90	60
Utah	90	90	88	54
Washington	90	90	88	56
Wyoming	98	90	89	60
Sources: Energy Information Administration, Estimation of U.S. Coal Reserves by Coal Type: Heat and Sulfur Content, 1987 data (1989); also Coal Reserves Data Base Program, Office of Coal, Nuclear, Electric and Alternate Fuels (1998) and Form EIA-7A, "Coal Production Report" (1992-1996).

 

Table 14. Estimated Recoverable Reserves of Coal in the United States by Sulfur Range and Major Region (Remaining as of January 1, 1997)
Coal-Producing Region	Summary Sulfur Content Categoriesa (Pounds of Sulfur per Million Btu)
	Low Sulfur ( 0.60)		Medium Sulfur (0.61-1.67)		High Sulfur ( 1.68)		Total
	Million Short Tons	Percent of Total	Million Short Tons	Percent of Total	Million Short Tons	Percent of Total	Million Short Tons	Percent of Total
Surface
Appalachia	4,311.5	( 9.5%)	6,785.9	(15.5%)	5,186.3	(16.0%)	16,283.6	(13.4%)
Interior	126.7	( 0.3%)	7,164.1	(16.4%)	20,544.2	(63.4%)	27,835.1	(22.9%)
West	40,963.3	(90.2%)	29,801.5	(68.1%)	6,686.2	(20.6%)	77,451.0	(63.7%)
U.S. Total	45,401.5	(100.0%)	43,751.6	(100.0%)	32,416.6	(100.0%)	121,569.7	(100.0%)
Underground
Appalachia	7,363.5	(13.4%)	13,550.8	(32.9%)	18,096.7	(31.4%)	39,011.0	(25.4%)
Interior	642.1	( 1.2%)	2,877.1	( 7.0%)	37,421.3	(65.0%)	40,940.5	(26.7%)
West	46,812.1	(85.4%)	24,727.3	(60.1%)	2,082.0	( 3.6%)	73,621.4	(47.9%)
U.S. Total	54,817.7	(100.0%)	41,155.2	(100.0%)	57,600.0	(100.0%)	153,572.9	(100.0%)
Total
Appalachia	11,675.0	(11.6%)	20,336.7	(24.0%)	23,283.0	(25.9%)	55,294.7	(20.1%)
Interior	768.8	( 0.8%)	10,041.2	(11.8%)	57,965.5	(64.4%)	68,775.5	(25.0%)
West	87,775.4	(87.6%)	54,528.8	(64.2%)	8,768.2	( 9.7%)	151,072.4	(54.9%)
U.S. Total	100,219.2	(100.0%)	84,906.8	(100.0%)	90,016.7	(100.0%)	275,142.6	(100.0%)
aFor detailed analyses, the EIA uses six sulfur content ranges. For general discussion and summary data, however, those six ranges are combined into the three qualitative ratings of coal presented here (low-, medium-, and high-sulfur content).     Notes: Coal supply regions that comprise each coal-producing region above are listed in Table 17. Data may not equal sum of components due to independent rounding.     Source: EIA Coal Reserves Data Base program, State geological and mineral resource surveys, and other geological reports.

Although the summary data in Tables 12 and 14 are both derived from the DRB database, differences in the char-acteristics of the mines and coal types in the three regions cause differences in data distribution. For example, the surface-minable DRB in Appalachia constitutes 17 percent of the DRB of the United States but only 13 percent of the estimated recoverable reserves, while in the West the surface-minable DRB is 58 percent of the national DRB but makes up a higher portion--64 percent--of the estimated U.S. recoverable reserves. The differences between DRB and recoverable reserve portions reflect the higher accessibility and recovery rates achievable in the West.

Further, in Appalachia, the surface accessibility factors average only 70 percent--lower than in the West because of more land use constraints and physical minability restrictions. Also, Appalachian accessibility is skewed by the extremely low rate of accessibility in the Pennsylvania anhracite region (14 percent). With that region excluded, the surface accessibility factor would rise to 77 percent. Surface accessibility in eastern Kentucky at 71 percent  is also well below the regional average. This low percentage reflects the fact that in eastern Kentucky many of the thin coalbeds in the surface-minable DRB are mined only selectively.⁽³⁾ The DRB is considered to be inaccessible for thin coalbeds in eastern Kentucky in districts and thicknesses currently not commercially minable.

Finally, the surface mining rates of recovery are kept lower in Appalachia by the need to mine in thinner beds and (to varying degrees) in more difficult topography, in more indurated overburdens,  and  with  more frequent groundwater and surface water concerns than in the major Western coal supply areas. Appalachian recovery rates average about 81 percent for the coal resources considered accessible.

In the West, surface accessibility factors average 91 percent. They are relatively high primarily because of fewer land use constraints and fewer known physical minability restrictions than in the East. The Geological Survey of Wyoming estimated that 98 percent of the DRB in that State may be accessible. Only in northern Alaska has EIA estimated a low rate of accessibility (50 percent), because of the difficulties of mining in tundra and permafrost and the absence of relevant experience mining under those conditions in the United States.

Surface recovery rates in the West are also high, averaging 90 percent for accessible coal resources. Many of the most productive mines recover thick coalbeds (40 to 100 feet are not uncommon), with relatively thin overburden, developed in soft types of rock or unconsolidated sediments. Even in harder rock, where more blasting is required, the overburden ratios tend to be low and the mechanical loading of the thicker coalbeds efficient. Net recovery rates in Western coals may also tend to be higher in areas such as New Mexico and Washington, where the coal contains thin partings of shale that cannot be avoided by mining equipment. These rock contaminants are mined through, raising the mined tonnage reported and the apparent rate of recovery, as the coal is generally not washed. These coals are accepted for combustion at nearby mine mouth power plants with 20 percent or more ash-forming material and lower heat value than if they were cleaned, but with minimal transportation costs. The reported rates of recovery, with no losses of product due to coal cleaning, are therefore very high, compared with typical Eastern coals, prepared for rail or barge shipment.

Differences in the relationships when comparing underground DRB and estimated recoverable reserves in Appalachia and the Interior likewise indicate differences in coal types, markets, and mining patterns (Tables 12 and 14). Appalachian underground coal makes up 23 percent of the DRB but accounts for 25 percent of the estimated U.S. recoverable reserves. Accessibility is not as restricted for underground mining in Appalachia and has fewer restrictions than the surface mines of the region. Again, the exception to the rule is Pennsylvania anthracite, where access for deep mining is severely restricted now and for the foreseeable future as a result of catastrophic flooding caused by Hurricane Agnes in 1972, drowning many of the mines and impairing adjacent resources. In general, however, net recovery of Appalachian deep coal deposits is good, primarily because much of the coal being mined is relatively high-quality, high-Btu fuel. The coal fetches prices that can support more costly mining technologies, including longwalls (67 percent of U.S. longwall production is in Appalachia⁽⁴⁾).

By contrast, 35 percent of the national DRB for underground mining is found in the Interior Region, but the estimated recoverable reserves constitute only 27 percent. The coalbeds in the Interior include a high percentage of thick beds, yet the net underground recovery is relatively low (52 percent versus 58 percent in Appalachia⁽⁵⁾). This lower recovery correlates with a region of high average sulfur contents, flat markets, and relatively low prices ($22.43 for Interior bituminous versus $27.67 for Appalachian bituminous, mined underground, average price per ton for calendar year 1996⁽⁶⁾).

The Coal Reserves Data Base program is EIA's vehicle for revision of the DRB, estimated recoverable reserves, and coal quality allocations. The CRDB data are revised using coal resource data and coal quality analyses sampled in and selected for their applicability to the coal resources. For the coal supply areas where CRDB projects are not currently feasible, the EIA continues periodic adjustments of the existing data to account for resource depletion. This is done to maintain a unified national database of the remaining DRB and estimated recoverable reserves adjusted to the latest common effective date.

A "base year" (Table 15) is the effective date of the detailed resource assessment for a DRB resource area, including adjustments for all known coal mined out and/or lost to mining as of the stated date. Some source studies on which the DRB is based may be much older than the base year or may have been done at various times over a range of years. A latest common effective date is used to maintain internal database consistency. It is the "as of" date to which data of varying base years are adjusted to account for subsequent production and coal lost in mining.

Although major updates are being made in the CRDB, some important coal supply areas are still based on 1971 base year DRB data and on allocations performed in the 1980s for the EIA's Resource Allocation and Mine Costing (RAMC) model(Table 15). The DRB covers all States for which there are sufficient coal resource data to compute a reserve base. Beginning with the 1992 update year, coal quality allocations were extended to all DRB data, including those not used in RAMC, for which allocations had not previously been done. Table 15 summarizes the resource data sources and base years used in the 1997 DRB and estimated recoverable reserve updates.
 

Table 15. 1997 Status of Database Updates for Energy Information Administration (EIA) Coal Resource and Reserve Data
Update Year	Base Year	Lead Agency	State or Producing Area	Source Comments
1996	1993	Kentucky Geological Survey	Eastern Kentucky field	1983 coal resource data, State coal analyses, USGS availability data, EIA recovery and accessibility data.
1997	1996	Illinois State Geological Survey	Illinois	State coal mapping system, coal analyses, USGS availability data, State and EIA recovery data and accessibility standards.
1994	1993	New Mexico Bureau of Mines and Mineral Resources	New Mexico portion of San Juan Basin and its southern extensions	State mapping system and coal quality data, company data, BLM land use data, State and EIA depletion and recovery data.
1995	1991	EIA	New Mexico portion of Raton Basin	Resource data from published report, accessibility estimated, EIA recovery data.
1992	1981	EIA	Pennsylvania (anthracite)	Resource data and accessibility from published study, EIA recovery estimates.
1992	1991	Geological Survey of Wyoming	Wyoming, surface-minable DRB of major coalfields	State coal resource files and published studies, State coal analyses and FERC data, USGS maps for land use, State and EIA production and active-mines reserve data.
1991	1991	Ohio Geological Survey	Major coal-bearing counties of Ohio	Resources from new State data points, State coal analyses, except: published study for non-priority counties; accessibility from State estimates and EIA analysis of National Forest and roadway restrictions.
1991	1979 (based on 1946-1980 studies)	EIA	Arkansas, Colorado, New Mexico, and Virginia (anthracite fields), Alaska (northern), Georgia, Idaho, Michigan, North Carolina, Oregon	DRBs allocated to Btu/sulfur ranges using EIA coal quality data and published coal analyses.
1980-1986	1971, (based on 1907-1971 data and 1972-1985 updates)	EIA (core Resource Allocation and Mine Costing Model file)	Alabama, Alaska (southern), Arizona, Arkansas, Colorado,* Indiana,* Iowa, Kansas, Kentucky (western), Louisiana, Maryland, Missouri, Montana, North Dakota, Oklahoma, Pennsylvania (bituminous), South Dakota, Tennessee, Texas, Utah,* Virginia, Washington, West Virginia, Wyoming (underground)	Basic Btu/sulfur allocations done in 1980 and 1986, based on 1971 DRB and extended to various updated DRB estimates from small post-1971 studies.

   * Colorado revisions in the Somerset and Yampa Fields are under development. Revisions in Utah are in progress. Revisions in Indiana are scheduled to begin in January 1999.

   1. Energy Information Administration, U.S. Coal Reserves: A Review and Update, DOE/EIA-0529(95) (Washington, DC, August 1996), pp. 31-37.

   2. Energy Information Administration, U.S. Coal Reserves: An Update by Heat and Sulfur Content, DOE/EIA-0529(92) (Washington, DC, February 1993) p. 24.

   3. As the results of more USGS Coal Availability Studies become available and, in general, as more up-to-date accessibility estimates are made, it is likely that additional instances of diminished accessibility to coal resources will be determined in Appalachia.

   4. Energy Information Administration, Coal Industry Annual 1996, DOE/EIA-0584(96) (Washington, DC, November 1997), p. 11.

   5. Ibid. p. 41.

   6. Ibid. p. 157.

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