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While the resource diagram in Figure 1-1 shows discreet
boundaries among the various geologic and economic sub-
classifications, these should not be taken as precisely
defined but rather indicative of where such a division would
occur. These transition zones must also be viewed in a
dynamic sense since changing economic conditions over time
could affect the categorization of resources.—
Coal Resource Classification
The coal resource classification system presently
adopted by the USGS and the USBM is based upon the general
resource classification system with certain modification.
All coal resource/reserve estimates from January 1, 1975
onward will be based on this system. The definitions and
criteria used in the coal resource classification system are
set out in full in Appendix B.
The major difference between the general resource
classification system and the coal resource classification
system is the distinction made with respect to recoverable
reserves. This distinction arises due to the fact that
fossil fuels by their nature of occurrence incur greater
extraction losses than due most metallic ores. For coal the
recoverable reserve can range from 50 percent to 80 percent
of the in-place resource. In the USGS-USBM coal resource
terminology this distinction is handled by introducing the
term reserve base which includes coal resources in place
while the term reserve or recoverable reserve is defined as
I/ For a more detailed discussion of the problems inherent
in a resource classification system the reader is referred
to an excellent study entitled: Resource Terminology;
An Examination of Concepts and Terms and Recommendations
for Improvement, J.J. Schanz, Resources for the Future,
August 1975.
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that portion of the reserve base that can be mined at the
time of classification (see Appendix B).
Another major addition to the USGS-USBM resource
terminology as it applies to coal is the use of seam depth,
thickness and quality criteria in estimating the different
classes of coal resources. This addition simply incor-
porates historical coal resource estimation procedures used
by the USBM into the new resource classification system.
The criteria are set out in Appendix B.
As pointed out in a recent study of resource terminology
there are several problems inherent in the use of the afore-
mentioned criteria to define parts of the resource system.—
First, the use of depth and thickness criteria the study
states "are not relevant to whether or not coal should be
classified as the identified or undiscovered." The use of
the criteria by the USDI results in the paradoxical situation
that resources found which do not meet the criteria are
known to exist but at the same time excluded from the resource
accounting framework. The rationale for this procedure is
based on the assumption that such coal would probably never
be produced. Another problem, identified in the study, with
respect to the economic dimension of the coal resource
classification system is the distinction between the econ-
omic coal reserves and subeconomic coal resources when
evaluated under the depth and thickness criteria for dif-
ferent ranks of coal. The implication here being that the
criteria may not be the deciding factor in determining
whether coal should be included in the economic or sub-
economic category. Finally, the study suggests that the use
of a time dimension particularly in the subeconomic classifica-
tion would help to reduce the reliance on strict definitional
I/ Ibid, pp. 38-39.
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criteria and give more emphasis on what coal could be pro-
duced over a certain period of time within a more flexible
criteria set'.
This discussion has served to indicate how resources,
particularly coal resources, are presently defined and what
problems and ambiguities exist in this area. This should
provide the reader with a better understanding of the subject
matter to be discussed in the next section. The classifica-
tion system provides a standard of comparison against which
the studies may be evaluated with respect to definitional
consistency.
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2.0 SUMMARY OF STUDIES ESTIMATING COAL RESERVES/RESOURCES
BY SULFUR CONTENT
2.1 Introduction
The purpose of this section is to present a summary
of those studies which have estimates of coal reserves/
resources by sulfur content. An assessment of differences
and a comparison based on set major parameters is presented
in the next section. The summaries provide an overview of
the assumptions, data sources, and methodology employed in
each study. In addition, the reserve/resource data for each
study are set out as they appear in each study. The data in
some cases have been summarized on a state, regional, and
national basis. The coal resource data in each study have
also been compiled by the rank of coal (i.e., lignite,
subbituminous, bituminous, anthracite) where possible since
this has an important bearing on the sulfur content distri-
bution.
We have endeavored in this study to include all major
publicly available studies which have sought to present
reserve/resource estimates by sulfur content. As a starting
point, we selected the U.S. Bureau of Mines Information
Circular (1C 8312) Sulfur Content of United States Coal.
This study published in 1966 was the first major effort to
present data on coal resources by sulfur content. Subsequent
studies relied on 1C 8312 as the basis for additional resource
estimates. We believe that by starting with the earliest
study a line of continuity is provided, thereby providing
additional insight into the resource estimates developed
thereafter. The summary will proceed in chronological order
in which the studies were published. Before commencing the
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summary, it is helpful to have an overall perspective on
the total coal resource as estimated by the USGS.
2.2 Overview of U.S. Coal Resources
The primary source of information with respect to the
domestic coal resources is the USGS. Periodically, revised
estimates of coal resources have been published by the
Survey. In order to provide a recent historical record data
are set out in Table 2-1 from three USGS studies. The
first, a progress report, published in 1961 shows only coal
reserves as of January 1, I960.— The second and third
studies estimated coal resources as of January 1, 1967 and
2/3/
January 1, 1975, respectively. —'—' The third and most recent
USGS estimate sets out the resource estimates within the
framework of the Interior resource classification system
(supra). The purpose for setting out these data is twofold:
first, it provides a logical point of departure for discus-
sing the resource estimates by sulfur content and second, it
provides a useful benchmark against which the total resource
can be compared.
I/ Coal Reserves of the United States - A Progress Report
January 1, 1960, Geological Survey Bulletin 1136.
2_/ Coal Resources of the United States January 1, 1967
Geological Survey Bulletin 1275.
3_/ Coal Resources of the United .States January 1, 1974
Geological Survey Bulletin 1412.
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TABLE 2-1
U.S. COAL RESOURCE ESTIMATES MADE BY USGS
(Million Tons)
Bulletin 1136
Bulletin 1275-/
Bulletin 1412-/
Resource Classification
Coal Rank
A.
B.
Identified
Anthracite
Bitimunous
Subbituminous
Lignite
Subtotal
a/
Hypothetical-
Total
(1960)
Remaining
Resource
(1)
15,328
760,554
436,812
447,596
1,660,240
N.E.
1,660,290
(1967)
Remaining
Resource
(2)
12,969
671,049
428,210
447,647
1,559,870
1,313,080
2,872,955
(1974)
Remaining
Resource
(3)
19,662
747,357
485,766
478,134
1,730,919
1,849,649
3,580,568
N.E. - Not estimated.
a/ Overburden Depth 0-3000 feet.
b/ Superseded Bulletin 1136.
c/ Superseded Bulletin 1275.
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Table 2-1 indicates that there has been some variation
in the estimates over time. This stems from both definitional
changes and the inclusion of more recent geologic data. At
the time Bulletin 1136 was published the term reserve was used
in a much broader context than it is now. Hence, the estimate
shown for remaining reserves should more correctly be classi-
fied as remaining resource, which makes it comparable to the
estimates made in the subsequent Bulletins. Comparing the
total identified resource estimates, which are based on more
complete geological information, Table 2-1 shows that the
identified resource estimates decreased slightly from 1960
to 1967 and then increased in the 1974 estimate. This in-
crease stems primarily from additional data which has been
incorporated into the USGS estimates. The inclusion of the
hypothetical resource estimates, while not included in the
1960 estimate, was shown for both 1967 and 1974 in order
to provide a more complete description of coal resources in
known producing areas. As could be expected the inclusion
of more recent data increased the hypothetical resource
classification significantly in the 1974 estimate. It should
be noted that resource data in Table 2-1 has only been
presented for overburden depths up to 3000 feet, since this
would be most relevant for the purposes of the study.
2.3 Summary of Studies Estimating Coal Resources
by Sulfur Content
As previously stated, this section will summarize those
publicly available studies which have sought to estimate coal
resources by sulfur content. Each summary will set out the
purpose for which the study was intended, the data sources
used, major assumptions underlying the estimates and finally
the reserve or resource estimates. The summary will proceed
in chronological order.
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2.3.1 Sulfur Content of United States Coals - Joseph A.
DeCarlo, Eugene T. Sheridan, and Zane E. Murphy -
U.S. Bureau of Mines Information Circular 8312, 1966.
This study was the first attempt to estimate the sulfur
content of the U.S. coal resource, and provided base data
for subsequent studies. One of the purposes of the report
was to "assess the reserves of the various ranks of coal in
each state, according to sulfur content." In addition, the
study also estimated the sulfur content of U.S. coal production,
All data compiled in this review were obtained from industry
surveys of the Bureau of Mines and from U.S. Geological
Survey and various state geological survey publications.
The report states that the sulfur content distribution
was based primarily upon "thousands of analyses of coal
samples from individual mines over the past half century."
Where gaps existed in the coal sample data, a literature
search was made in order to assign a sulfur content to a
particular coal bed. Importantly, the report stated that
"in most instances the analyses used were those of cleaned
coal." The investigators believed, however, that this would
have little effect on the distribution of low sulfur reserves,
but could bias the distribution of higher sulfur coals down-
ward by 0.5 to 1.0 percent sulfur. The report presented no
discussion as to the method used to stratify reserves by
sulfur content. The investigation pointed out several of
the problems involved in determining the distribution of
reserves by sulfur content. Among these were the following:
1. Variations in sulfur content within a bed or seam.
2. Lack of reserve information for some geographical
areas.
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3. Lack of recent analysis for some beds; analyses
taken 25 to 40 years ago were used in some cases.
4. Lack of sufficient data on mine and channel samples
affected the assignment of sulfur content to reserves,
The reserves were stratified into sulfur levels ranging
from 0.7 percent or less to 4.0 percent and greater, increasing
at intervals of 0.5 percent, with the exception of the second
interval which went to 1.0 percent. The data were set out
by coal rank and state. Schedule 1 sets out the reserve
estimate by sulfur content as determined by DeCarlo, et. al.
The table as shown on Schedule 1 purports to show remain-
ing coal reserves as of January 1, 1965.— The basic source
document for reserve data was USGS Bulletin 1136 (supra)
adjusted for production losses through 1964, plus adjustments
for more recent information. The resultant total reserve
figure of 1,576 billion tons is not substantially different
from the total reserve estimate of 1,660 billion tons made
in USGS Bulletin 1136. As noted in Section 2.3.1, however,
in terms of the present Interior lexicon, the estimate should
more correctly be classified as identified remaining coal
resources.
DeCarlo, et. al., estimated that for all ranks of coal
in the United States, 65 percent of remaining reserves are
less than or equal to 1.0 percent sulfur, 15 percent of
remaining coal reserves range between 1.1 to 3.0 percent
sulfur while 20 percent of remaining reserves had a sulfur
content greater than 3.0 percent. The distribution of re-
maining reserves of all ranks in states east of the Mississippi
I/ All schedules are contained in Volume II,
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was 20 percent (95 billion tons) for a sulfur content of 1.0
percent or less; 37 percent (177 billion tons) for sulfur
contents ranging from 1.1 to 3.0 percent and 43 percent (206
billion tons) for sulfur contents greater than 3.0 percent.
2.3.2 • Analysis of the Availability of Bituminous Coal in
the Appalachian Region, United States Department
of the Interior, Bureau of Mines — Mineral Supply,
July 1971. Performed for Environmental Protection
Agency, Office of Air Programs
This report was the first attempt directed to a compre-
hensive appraisal of coal reserves, by sulfur content, in
the Appalachian region. Previous state, federal and industry
reports indicated the coal resources of the Appalachian region
were abundant. From the standpoint of quality, considerable
concern was expressed regarding the supply of coal containing
low quantities of sulfur. The primary objective of this
study was to determine the quantity of Appalachian coal
reserves by sulfur content, location by county, and the type
of reserve. A secondary objective was to gain insight into
the production and consumption of coal by sulfur content,
productive capacity of mines, and work force.
A special questionnaire was used to canvass selected
coal operators in the bituminous coalfields of the Appalachian
region (Alabama, eastern Kentucky, Maryland, Ohio, Pennsylvania,
Tennessee, Virginia and West Virginia). Responses to these
questionnaires were solicited during 1968 and 1969 and reflect
coal reserves as of December 31, 1967.
The special questionnaire was mailed to 701 operators of
mines with annual production greater than 100,000 tons of
coal during 1967. Importantly, the sample did not include
producers producing less than 100,000 tons per year nor did
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it include non-coal companies which have coal properties.
Data were collected from 91 percent of the 701 companies,
which represented more than 68 percent of the total coal
produced from the Appalachian region in 1967.
Coal reserves as shown on Schedule 2 were reported in
two major categories: remaining reserves and recoverable.
reserves. Remaining reserves were reported by state and
were divided into three categories: commercial, captive and
other. Each of these categories was further divided as to
reserves associated with operating mines, scheduled new mines,
and not assigned to mines. Moreover, all categories of re-
maining reserves were divided into eight ranges of sulfur
content. The recoverable reserves were divided by state
into the same divisions as the remaining reserves except for
the three mining categories. Recoverable reserves were
estimated at 1967 f.o.b. prices and f.o.b. prices ranging up
to $2 greater than the 1967 price.
Some important assumptions and estimates were apparently
left to the mine operators' discretion in the preparation of
the data. These assumptions include the minimum seam thick-
ness and maximum overburden constraints to recoverability,
and the knowledge of the physical characteristics (especially
specific gravity, sulfur content and continuity of a coal
bed). No field check was performed to assure the accuracy
of the data. These factors, and the fact that only companies
producing 100,000 tons or more in 1967 were canvassed, are
reported as significant points which cause a variation from
the remaining coal reserves reported in Bureau of Mines
Information Circular 8312 (supra).
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2.3.3 Survey of Coal Availabilities by Sulfur Content,
Mitre Corporation, May 1972.
This.study was prepared in behalf of the U.S. Environ-
mental Protection Agency. The objective of the study as
stated in the report was to "quantify current and future
potential availability of coal by sulfur content; in addition
to the rank of coal, in order to accomplish the stated
objective the study also examined coal reserves, steam coal
production and mining growth potential."
While Section 4.0 of the report is devoted specifically
to coal reserves, including distribution by sulfur content,
other sections of the report also set out reserve estimates.
Thus, it is far from clear exactly which estimates formed
the basis of the availability analysis.
The Mitre study grouped the various reserve estimates
on a regional basis. The regional designations are shown on
Schedule 3. It should be noted that Ohio was included in
the eastern Interior region rather than the northern Appala-
chian region, primarily on the basis of its higher sulfur
content.
As a starting point, the Mitre study sets out a
provisional estimate of U.S. coal resources as shown in
Table 2-2.
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TABLE 2-2
PROVISIONAL ESTIMATES OF COAL RESOURCES
OF THE UNITED STATES
Category • Amount
9
1. Known recoverable reserves 198 x 10 tons
2. Undiscovered recoverable
resources 150 x 10 tons
3. Known marginal and submarginal _
resources 1,380 x 10 tons
4. Undiscovered marginal and g
submarginal resources 1,500 x 10 tons
Total 3,228 x 109 tons
These estimates, according to the report, are based upon
USGS Bulletin 1275 (supra), although the total is higher.
The Mitre study defines known recoverable reserves as coal
occuring in "thick coalbeds lying at depths of less than 1,000
feet." The study defined the minimum thickness coalbed for
bituminous and higher rank coals as being 3.5 feet and for sub-
bituminous and lower rank coals 10 feet. In order to estimate
recoverable reserves, recovery factors of 50 percent were assumed
for underground mining, 60 percent for strip mines in the
Appalachian and Interior regions and 80 percent for strip mines
in the Rocky Mountain region. With the exception of undiscovered
recoverable resources, the remaining resource classifications are
for coal in place to a depth of 6,000 feet and assumed to be.
completely recoverable.
The derivation of the known recoverable reserve estimate
was apparently made by Mitre based upon the aforementioned
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criteria. The derivation as shown in the study is set out in
Schedule 4. The column showing total known reserves is based
upon the DeCarlo study 1C 8312 (supra), while the column
showing known reserves in thick beds less than 1,000 feet below
the surface is apparently based upon Table 5 in USGS Bulletin
1275.— It is important to note here that a problem in proper
nomenclature arises in Mitre classification since what are
referred to as reserves in the first column are in actuality
2/
resources.—'
The study then shows a breakdown of known reserves
(identified as resources categories 1 and 3 in Table 2-2) and
the estimated known recoverable reserves by sulfur content.
These data are shown on Schedule 5. The report states that
the sulfur distribution of the total known reserves is based
on USBM 1C 8312. The computation of known recoverable
reserves by sulfur is based upon the percent distribution
shown on the last column of Schedule 5, applied to the known
reserves estimate in each sulfur interval. The report notes
that the sulfur categories are given on a dry weight percent
basis .
The report next separately sets out an estimate of Rocky
Mountain strippable reserves by sulfur content by state and
coal region within the state. The reserve estimates are based
upon USBM 1C 8531, a study of strippable reserves. In order to
distribute the reserves by sulfur content, a data base was
developed from a sample of 1,959 coal analyses obtained pri-
marily from U.S. Government sources but also included state
I/ USGS Bulletin 1275, page 33.
2_/ The totals do not appear to be correct in the first
and third columns of Schedule 4. Upon readdition a
total of 1467 is calculated for total known reserves,
and 387 for known reserves.
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publications. This permitted an estimation of regional coal
characteristics. A distribution of samples by sulfur interval
was also developed and is shown on Schedule 6. Importantly,
the study points out that "due to the limited sampling and
possible geographic bias the numbers may not represent coal
in place and therefore should be used with caution."
The strippable reserve estimates for the Rocky Mountain
region are then set out by sulfur category based upon the simple
distribution shown in Schedule 6. The totals for each state
do not in most cases agree with the Bureau of Mines data, since
coal regions were excluded where no sample data were available.
The resultant estimates are set out in Schedule 7.
Another estimate of eastern remaining coal reserves by
sulfur as of 1968 is provided in a section of the study discus-
sing the effects of coal cleaning on coal availability. The
report states that the table was based on DeCarlo 1C 8312 and
the 1970 Keystone Coal Industry Manual. This estimate is shown
on Schedule 8. The report does not define remaining reserves;
in addition there is no discussion why the regional totals shown
in Schedule 8 differ from those developed earlier in the study
set out in Schedule 4.
2.3.4 Task Force Report on Fuels Availability - Prepared for
Technical Advisory Committee on Fuels, Federal Power
Commission, National Power Survey, July 25, 1973
The purpose of this report was the "study, analysis, and
reporting on information relative to the availability of fuels
for electric power production including data on location, quantity,
quality, extraction, capability, transport and conversion costs
. . . ." The members of the task force responsible for the
sections of the report dealing with coal were J. DeCarlo, who
at that time was with the Department of Interior; C.E. Groves,
TVA; and J.A. Simons, Illinois State Geographical Survey.
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The coal section of the report discussed consumption,
availability and factors affecting future production, in
addition to a discussion of coal resources and reserves. In
the discussion of reserves, a table is set out showing esti-
mated recoverable coal reserves as of January 1, 1972. This
table is reproduced here as Schedule 9. The source of the
estimates is USGS Bulletins 1136 and 1275 (supra) modified
to reflect only the measured and indicated reserves under
1,000 feet of overburden and in seams 28 inches or more in
thickness for bituminous and anthracite coals and five feet
or more for lignite and subbituminous. The reserves were
stratified by three major sulfur categories: less than 1.0
percent, 1.0 to 2.0 percent and greater than 2.0 percent.
No discussion was provided as to the procedure used to
determine the distribution of reserves by sulfur content.
In addition to sulfur content, data with respect to
average ash content and heat content were also shown on
the table.
With respect to the reserve data the report stated the
following:
"The reserve data for the eastern part of the
U.S., where mining has been conducted for decades, is
subject to little change other than refinement of data.
However, the figures for the western U.S. can be con-
sidered subject to substantial changes within the next
few years. Extensive exploration is being conducted by
federal and state agencies, as well as by mining companies,
to delineate the areas of low-sulfur coal in the West."
The report goes on to discuss suggested modifications in
the stratification of coal reserves by sulfur content, noting
that a finer breakdown would be desirable in order to accu-
rately calculate the emissions potential. On this point the
report states the following:
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"This could prove to be a horrendous task
because sulfur contents often vary widely within
a coal seam even in the same locality. At the
same time, the sulfur content should be tied to
the actual Btu content /i.e., not to an average
for a state or a range of values/ and for a
relatively restricted locale, so that effective
emission calculations could be made."
2.3.5 Babu, S.P., et al., Suitability of West Virginia Coals
to Coal-Conversion Processes, Coal Geology Bulletin
No.1, West Virginia Geological and Economic Survey,
December 1973.
The West Virginia Geological and Economic Survey provides
a generalized study of the quantitative and qualitative char-
acteristics of West Virginia's coal resources. The primary
objective of the study is to provide recommendations for
national utilization of these resources in large-scale coal
conversion plants. Specifically, the study recommends five
suitable plant sites and identifies the coal conversion process
most amenable to each site with respect to coal characteristics,
water requirements, and transportation requirements for raw
materials and conversion plant products.
The sources of the estimated original minable reserves
and remaining recoverable reserves are not identified. However,
the 117 billion tons of estimated original minable reserves
reported in this study are in agreement with the 116.6 billion
tons reported by Averitt (1974).— The recoverable reserves
estimated at 58 billion tons, appears to be an assumption that
about half of the original minable reserves are recoverable.
I/ Averitt, Paul, Coal Resources of the United States,
January 1, 1974, U.S. Department of the Interior,
Geological Survey Bulletin 1412, 1975. The estimates
by Headlee and Nolting (1940).
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The sulfur content of the recoverable reserves was derived
from 5,997 as received coal analyses. The majority of these
analyses (4,908) were collected and reported by Headlee and
Nolting— and represent 2,528 mines, prospects, openings,
outcrops and drill cores from 75 seams. The remaining 1,089
analyses were tipple samples collected by the West Virginia
Geological Survey and the Bureau of Mines.
The 5,997 average as-received analyses were identified
by latitude and longitude and the mean values were trans-
ferred to computer cards representing five minute quadrangles
on a control map of the state as shown on Schedule 10. Super-
imposing the computer plot of these analyses on a map of the
minable coal in West Virginia provided the estimates of
recoverable coal reserves as a function of rank and sulfur
content as shown on Schedule 11. Of the estimated 58 billion
tons of recoverable reserves 20 billion tons have sulfur
contents less than 1.0 percent, 35 billion tons have sulfur
contents less than or equal to 1.5 percent, and 48 billion
tons have sulfur contents less than or equal to 3.0 percent.
Although it is noted that there are certain limitations
to the graphical averaging and plotting techniques utilized
in this report, these limitations are not specified.
2.3.6 Low Sulfur Coal; A Revision of Reserve and Supply
Estimates. Appendix C, The Coal Future: Economic
and Technological Analysis of Initiatives and
Innovations to Secure Fuel Supply Independence,
Rieber, M., et al., Center for Advanced Computation,
University of Illinois at Urbana-Champagne, May 1975.
I/ Headlee, A.J.W., and Nolting, J.P., Jr., "Characteristics of
Minable Coals of West Virginia," v.XIII, West Virginia
Geological Survey, Morgantown West Virginia, p.272, 1940.
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The analysis of coal resources and reserves was part
of a larger study whose objective it was to identify "those
areas where the expected relative payoff of increased govern-
ment expenditures on research and development, taxes and
subsidies, and other incentives designed to expedite the in-
crease in economically recoverable domestic reserves of
coal, the commercial upgrading of coal to superior end-use
products, and innovations leading to lower cost coal trans-
portation is highest."
While Section III of the main report is devoted to coal
reserves, resources and production, the basic research is
described in Appendix C. The purpose of the research related
to coal resources and reserves was to examine the reserve/
resource, base assessment and classification and the distri-
bution by sulfur content. A computational adjustment based
upon a common Btu assumption was used to redistribute re-
serves by sulfur content. The details of this computational
adjustment process are discussed in detail below. Using
this approach the report states that: "Based on Bureau of
Mines data, our study shows that the reserves of low sulfur
coal in the U.S. are about 75 percent lower than published
estimates. Reserve estimates of low sulfur coal in the far
west should be reduced by 85 percent. The estimating pro-
cedure used in the study puts all coal on a common Btu
basis, which is what a consumer does for coal comparisons,
and reassigns the coal to the corrected sulfur class."
The resources and reserves section in Appendix C commences
with a discussion of various estimates made by the Interior
Department, Bureau of Mines, National Petroleum Council and
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and Mitre Corporation (supra).—' After sorting out which of
the aforementioned studies are referring to resources and
which are referring to economically recoverable reserves,
Rieber, et al., decided to use the Mitre study estimate of
recoverable reserves, since as the report states "this paper
is concerned primarily with reserve data in terms of sulfur
content." The report notes that the Mitre estimates are
lower than the other resource estimates reviewed; however,
the report states "this is not important. Given the proper
conditions of price and technology resources tend to become
reserves."
Utilizing the Mitre data on U.S. resources and recoverable
reserves, plus the sulfur distribution estimated by DeCarlo in
1C 8312 (supra), Rieber reproduces the data in slightly
different format, by showing the ranks of coal separately
and by adjusting the eastern Interior region for revised
sulfur distribution data pertaining to Illinois. This table
is reproduced on Schedule 12. Rieber points out that the
sulfur distribution developed by DeCarlo may be somewhat
misstated since for the most part cleaned coal samples were
utilized. Rieber also points out that "looking at Table 2
(Schedule 12) a casual addition of all coals in the £0.7
percent sulfur content by weight category is not warranted."
Nevertheless, he does show a grand total for all ranks on
Table 2. The apparent reason for his comment is the imper-
fect substitution of one type of coal for another by end-
users such as electric utilities.
Rieber next sets out a recalculation of the reserve and
resource estimates based upon what he refers to as a compara-
ble Btu and effective sulfur basis. This estimate is derived
in the following manner: First, the volumes shown on
!_/ The National Petroleum Council's (NPC) estimate of coal
reserves did not include a stratification by sulfur
content. A summary of the NPC estimate is provided in
Appendix D.
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Schedule 12 were recalculated on the basis of a common Btu
value. This value is applied equally to all ranks of coal.
Thus, coal reserves with a heat content higher than that
selected as the common basis will be revised upward on a
tonnage base, while the converse is true of lower Btu value
coals. The value selected - 22.6 MMBtu/ton - represented
the average heat content of coal burned by electric utilities
as compiled by the Department of Interior at the time the
study was prepared. Rieber is careful to point out that the
calculation will be sensitive to the Btu value selected for
conversion. The result of this calculation was shown on
Table 4 in the report reproduced here as Schedule 13.
The next step was to redistribute the reserves by sulfur
content based upon the volumes computed in Table 4 (Schedule
13). In order to effect the calculation a mid-point sulfur
content was assumed for each of the sulfur intervals of the
original classification.— The mid-point percent sulfur
contents were then multiplied by the original amount of coal
in each sulfur category and region. This provided an esti-
mate of the total amount of sulfur. The amounts of sulfur
were in turn divided by the Btu adjusted volumes of coal
estimated for the particular sulfur interval. This cal-
culation provided a revised estimate of the average percent
sulfur content and thereby permitted the original resource
and reserve estimate to be redistributed according to the
revised sulfur contents. The result of the calculation was
shown in Table 5 reproduced here as Schedule 11.
I/ Rieber points out the problem in selecting the mid-
point, indicating that in actuality the shifts from
one sulfur interval to another would not be as clear-
cut as shown in the report; however, available data
prevented a refinement of the procedure.
-26-
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The final step, apparently, was to reconvert resource
and reserve data adjusted for sulfur content back to the
common Btu basis using the conversion factor shown on
Schedule 13. This results in a restatement of resources
and recoverable reserves on a common Btu basis and average
sulfur basis, as shown on Schedule 15. Apparently, data
were only presented up to the 1.6 to 2.0 percent sulfur
interval since the major emphasis was on low sulfur coal.
As stated in the report the reclassification results in
a 76 percent reduction in the total amount of coal in the
0.7 or less sulfur category, and a 17 percent reduction
in the 0.8 to 1.0 percent sulfur interval.
2.3.7 Impact of Increased Coal Use on the Clean
Fuels Deficit, Discussion Draft Report,
EPA Contract No. 68-01-2407, Task Order
No. 6, Sabotka & Company, Inc., February
14, 1975.
This study is presented in three parts. The first part
deals with a forecast of coal consumption; the second part
deals with coal supply forecast; and in the third part
the supply and demand forecasts are combined to estimate
clean coal deficits. The reserve estimates are presented
in part two of the report. In part two it is stated that
"supply estimates have been developed only for those
classes of coal that appear to be viable in the long run
with current emission standards."
Coal reserve estimates are developed on a regional
basis for five regions: Eastern, Central, Northern Plains,
Southwestern and Texas. Schedule 16 is a reproduction of
a map of the regions shown in the report. In addition,
the reserves are stratified by three major sulfur cate-
gories as shown below.
-27-
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Low-sulfur coal (LSC) = less than or equal to 1.2 Ib.
S02/MMBtu (i.e., coal that conforms to NSPS for sta-
tionary sources) •
Medium sulfur coal (MSC) = 1.21 - 3.20 Ib. SO./MMBtu
(i.e., does not conform to NSPS but does conform to
less stringent SIPS).
High sulfur coal (HSC) = greater than 3.20 Ib. S02/MMBtu
(i.e., meets neither NSPS nor SIP).
Exhibit II-2 in the report, reproduced here as Schedule
17, sets out Sabotka's estimate of recoverable reserves.
There is no substantive discussion of the derivation of the
estimates in the text of the report. The footnotes in
Exhibit II-2 provide the basic sources of information. Thus
the estimate of total reserves is based upon the Report of
the Interagency Coal Task Force to the FEA Project Independence
Blueprint, Bureau of Mines, October 4, 1974.
The sulfur distribution is based upon the Mitre report
on coal availabilities by sulfur content (supra). No data or
information was provided in the report which explained what
procedure was used to convert from the sulfur to pounds of
S0_. The estimates assume recovery of 40 percent of the
underground, and 70 percent of the surface, reserve base
(measured and indicated deposits within 100 feet of the
surface with seam thickness of at least 28 inches for bitu-
minous and anthracite and at least 60 inches for subbituminous
and lignite).
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2.3.8 The Reserve Base of U.S. Coals by Sulfur Content,
two volumes, 1C 8680, The Eastern States and
1C 8693, The Western States, U.S. Bureau of Mines,
Department of Interior, 1975.
This report of the U.S. Bureau of Mines is the most
comprehensive to date with respect to estimated coal
reserves by sulfur content for the United States. The
report states that various other state and Federal agencies
have made coal resource and reserve estimates while the
present report attempts to do so on a uniform basis.
Eastern U.S. (1C 8680). The report sets out estimates
of the reserve base, (i.e., coal in place). "This includes
underground minable coal to a maximum depth of 1,000 feet;
strippable coal is usually to a maximum of 120 feet but this
maximum may be greater or less depending on local conditions."
The report states that extensive use was made of previous
reports on coal resources and reserves. Schedule 18 sets
out the basic resource data and the criteria used to esti-
mate the strippable reserve base.
The base data was adjusted for depletion as of
January 1, 1974. In this regard a factor of 1.25 times
bituminous and lignite strip production and 1.11 times
anthracite strip mining was to estimate depletion, while a
depletion factor for underground and auger mining of twice
production was used. The report states that the total
reserve base was first calculated from which the strippable
reserve base was deleted leaving the gross underground re-
serve base.
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The coal reserve base was, through statistical prob-
ability, distributed by increments throughout the range of
sulfur contents determined from coal-quality data on file in
the energy data bank maintained by the Bureau of Mines. The
report states that only raw-coal sulfur analyses were
collated with the reserve data to approximate the sulfur
content of in-place coalbeds. The computer distribution
includes all sulfur categories between the extremes of
highest and lowest; no tonnages of coal are allotted to
sulfur categories higher or lower than those levels actually
observed. The primary assumption underlying the distribution
of coal in the reserve base, by sulfur content, is that the
quality of coal remaining in the ground is basically equi-
valent to that which has been mined. This assumption did
not appear to be valid in the case of Illinois and Indiana
coalbeds. Past mining practices in these states were to
mine the low-sulfur coal first. As a result, previous
mining has substantially depleted the supply of low-sulfur
coal. To compensate for this fact the Bureau of Mines
performed a manual distribution of coal by sulfur content
based on the personal knowledge and judgement of individuals
familiar with Illinois and Indiana.
The source data for the probability distribution is
based upon more than 72,000 coal analyses for the Eastern
U.S. contained in the Bureau of Mines data bank. The sample
analyses appear to be based primarily on government coal
purchases as reported in publications under the generic
title Analysis of Tipple and Delivered Samples of Coal.
The span of these reports date from 1971 back to 1951. In
addition, other reports were used dating back to 1913,
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containing samples taken in 1904. No discussion was pro-
vided in the report with respect to the type of probability
curve estimated.
The report sets out in considerable detail reserve
estimates by county and coal seam. In addition, a separate
appendix sets out a computer printout of the coal character-
istics by county and coal seam based upon the sample analyses,
It would not serve the purposes of this report to reproduce
the detailed information; hence, only the summary tables are
presented. Schedule 19 sets out the data by rank of coal
and state for the Eastern U.S. as well as the Western U.S.
The data has been adjusted to include the revisions for
Illinois and Indiana.
Western U.S. (1C 8693). The overall procedures used to
estimate the reserve base for the Western U.S., defined in
the report as total measured and indicated reserve classifi-
cations to a depth of 1,000 feet, are similar to those
utilized for the Eastern U.S. The major differences being
possibly the specification of minimum coalbed thickness,
overburden depth and stripping ratios as the basis for
determining the reserve base. Apparently the source data
for the reserve base estimates were derived from various
geologic survey reports for individual states dating back
over some 25 years. These criteria were set out in the
report on Tables 2 and 3 and are reproduced here as
Schedule 20.
Depletion was calculated for the resource estimates for
each state, rather than on an individual coal seam basis due
to a lack of data. Apparently, the depletion estimate was
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made independently of sulfur content. The depletion table
set out in the report is shown below.
TABLE 2-3: COAL DEPLETION BY STATE AS OF JANUARY 1, 1974-^
State
Alaska
Arizona
Arkansas
California
Idaho
Iowa
Kansas
Missouri
Montana
New Mexico
North Dakota
Oklahoma
Oregon
South Dakota
Texas
Utah
Washington
Wyoming
2/
Depletion— , million tons
42
10
205
7
1,175
1
727
32 (1957)
646
377
335
-
392
8
61
650
11 (I960)
203/ (Jan. 1, 1973)
I/ Depletion was calculated from date of resource estimate.
2] Except where data are given in parentheses, depletion is
based on the original amount of coal in the ground before
mining took place.
3/ Preliminary.
In addition, some coal could not be classified for
inclusion in the reserve base and was, therefore, unclas-
sified. These unclassified volumes were set out in a
separate table reproduced below.
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TABLE 2-4; UNCLASSIFIED COAL BY STATE
Unclassified coal,
State million tons
Arizona 4,373
Arkansas 32
California 100
Colorado 12,373
Idaho 9
Kansas 16,951
New Mexico 358
Texas 7,059
Utah 7,862
Total 49,117
With respect to the sulfur distribution of the reserve
base the report states the following:
"Sulfur levels by individual bed tonnages were
determined by applying a weighted average of all
available sulfur sample values (on a dry basis) for
individual beds. Where no sulfur analyses were avail-
able by bed and/or county, tonnages were placed in the
"Unknown" category. It should be emphasized that
tonnages subdivided by sulfur levels are based in some
instances on older coal samples. Therefore, coal of a
particular sulfur level in the tables may now actually
be depleted. Lignite is not considered in the reserve
base for underground mining because it is not economi-
cally feasible to mine underground owing to the low
Btu value."
The report did not indicate specifically what sources
of information were used to obtain the coal sample analysis
data upon which the sulfur distribution was based. Schedule
19 sets out a summary of the reserve base estimate by state
and rank of coal.
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2.3.9 Analysis of the Supply Potential for Southern
West Virginia Low Sulfur Coal, EPA Contract
No. 68-01-2428, Charles River Associates, Inc.,
January 1976.
This study was conducted for the Policy Planning
Division of EPA. As stated in the report, "The study
investigated the potential for output expansion from
the southern West Virginia low-sulfur coal field. Metal-
lurgical coal demand for the area was also analyzed in
order to isolate the availability of NSPS-acceptable
coal to steam coal customers. In order to forecast
future supply, it was necessary to analyze the adequacy
of the reserve base, to forecast future productivity
levels and input prices, and to investigate potential
supply bottlenecks and growth constraints."
The study area, Southern West Virginia,— was
selected because it has historically been identified as
a key low-sulfur producing area. The counties included
in the study area are set out below.
WEST VIRGINIA COUNTIES IN STUDY AREA
1. Boone 11. Mercer
2. Cabell 12. Mingo
3. Clay 13. Monroe
4. Fayette 14. Nicholas
5. Greenbrier 15. Pocahontas
6. Kanawha 16. Putnam
7. Lincoln 17. Raleigh
8. Logan 18. Summers
9. McDowell 19. Wayne
10. Mason 20. Wyoming
I/ Southern West Virginia is alternatively defined as
part of the producing Districts 7 and 8 as defined
by Bituminous Coal Act of 1937.
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Coal reserves are discussed in Section 3 of the report.
The study relies on estimates of the reserve base as presently
defined by the Bureau of Mines and USGS as relevant for the
intended purpose of the study. Reserve base estimates are
set out separately for underground and strippable reserves.
Table 3-2 of the report, reproduced here as Schedule 21, sets
out the reserve base of underground coal by sulfur content
as of January 1, 1971. The data were reproduced from U.S.
Bureau of Mines 1C 8655. These data were subsequently
included in USBM 1C 8680 (supra).
By interpolating across sulfur contents in the table
the study estimates the area contains 4,881 million tons of
0.7 or less percent sulfur coal, 9,489 million tons of coal
with 1.0 percent or less sulfur, and 12,393 million tons of
1.5 percent sulfur coal.
Additionally, the study finds that, "Because of the
high heat content of study area coal, NSPS-acceptable coal,
when defined as coal of less than 0.6 pounds sulfur per
million Btu, substantially exceeds the reserves of 0.7
percent sulfur coal. The study area contains 6,548 million
tons of NSPS-acceptable (underground reserves) and an ad-
ditional 7,734 million tons of other reserves of less than
1.6 percent sulfur."—
Apparently the data for sulfur, ash and heat content
were all derived from the Bureau of Mines report cited
above. No indication was given whether these data were
reported on an "as received on dry basis."
I/ The heat content of a substantial portion of the low
sulfur coal in the study area was found to be above
13,000 Btu/lb.
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The majority of the study area reserves are reported
as minable by only underground methods. Only 1,487 million
tons or slightly more than 8 percent are currently consid-
ered minable by surface methods. The sulfur contents of
the study area strippable reserves were estimated and set
out in Table 3-6 of the report, reproduced here as Schedule
22. Due to a lack of more precise breakdowns of sulfur
content and Bureau of Mines information limited to five
counties in the study area, the estimate is reported to be
crude. The principal assumptions which underly the estimate
are: (a) the low-lying (geologically) reserves are strippable
in the study area, an assumption which coincides approximately
with the stratigraphy of the state, and (b) the relationship
between heat and sulfur content equals the average relation-
ship for the study area underground reserves. •
This report also attempted to analyze any bottlenecks
or growth constraints due to ownership or control of the
coal reserves. Although data on the ownership was avail-
able for coal lands representing 98.1 percent of the study
area production in 1973, the study seems to indicate no
defensible conclusions can be made. The difficulties with
using ownership data to determine the extent of control of
reserves stem from the fact that many reserves are control-
led via long term leases rather than ownership of mineral
rights.
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3.0 COMPARISON AND ANALYSIS OF COAL RESERVE/RESOURCE
ESTIMATES BY SULFUR CONTENT
3.1 Introduction
This section has a twofold purpose: first to identify
those factors which account for differences in the estimates
of reserves and/or resources by sulfur content. Second, to
analyze the basis for such discrepancies. Only those studies,
previously reviewed, which explicitly set out reserve/resource
estimates by sulfur content are included in this section.
Rather than analyze each study separately, the approach
will be to analyze the various studies under a common set of
criteria which will provide for a systematic identification
of any differences. The major criteria include: geographic
study area; date of estimate; terminology including geologic
and economic assumptions; and sources of data. In addition,
the computational procedures used to derive the tonnage
estimates and sulfur distribution will be examined.
Schedule 23 sets out a summary of the relevant para-
meters for the studies analyzed herein. Each study will be
referenced according to the designation shown in column 2 of
Schedule 23. The studies are presented in the schedule in
the order of decreasing comprehensiveness with the geographic
study area and data base. Thus, the Bureau of Mines study
is presented first since it encompasses the Nation and
contains a substantial data base. The Charles River study
is listed last since it is concerned with the smallest
geographic area and accordingly has a smaller data base.
-37-
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While the studies were completed variously over a span of
ten years, as shown in column 3, the major thrust of each
is basically the same - the availability of coal to meet air
quality regulations. The starting point in each study has
been a statement of national or regional reserve/resource
position by sulfur content, which indicates the fundamental
importance of these estimates to any discussion of supply or
availability.
3.2 Comparison of Studies Based upon Geographic
Study Areas and Rank of Coal, and Date of
Reserve/Resource Estimate
In assessing the differences in the reserve/resource
estimates among the various studies, the most obvious
starting point is to examine those parameters which more or
less define the overall boundaries .of the estimates. Such
parameters could be considered independent of the actual
computation of the estimates by sulfur content. In this
category we include the date of the reserve/resource es-
timate, the geographic study area and the types of coal
included in the estimates. The discussion of discrepancies
occurring in resource terminology, estimation criteria and
sulfur distribution will be facilitated by first elucidating
any differences or discrepancies occurring among these para-
meters.
As shown in Schedule 23, six of the nine studies reviewed
are national in scope, and in addition present a state
and/or regional designation. One of the studies (USBM)
dealt specifically with the Appalachian region, while two of
the studies (CRA and W.Va.G.S.) are oriented to a state
specific analysis.
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3.2.1 Geographic Study Areas
Six of the studies shown in Schedule 23 identify the
geographic study area as the total United States. These
are: 1C 8680-93, Sabotka, Rieber, FPC, 1C 8312, and Mitre.
An examination of the individual studies reveals that the
geographic parameters exhibit some differences. ic 8312
appears to be the most extensive and provides estimates for
all 35 states. Generally, 1C 8312 combines several states
with minimal reserves in a category designated as "Other
States." As an example, the "Other States" category for
bituminous coal in 1C 8312 contains an estimated 616.0
million tons. The states included in this category are
footnoted as Arizona, California, Idaho, Nebraska and Nevada.
On a geographical basis, 1C 8680-93 provides an estimate
of the coal reserve base for 30 states. The difference in
the number of states in this study when compared to the 35
states reported in 1C 8312 is due to the exclusion of 5 states:
California, Idaho, Louisiana, Nebraska and Nevada. Quantita-
tively, these states account for approximately 4 billion
tons or about 0.3 percent of the grand total in 1C 8312.
However, it should be noted that 1C 8312 is an estimate of
identified coal resources, while 1C 8680-93 is an estimate
of the coal reserve base. As such, it is possible that a
coal reserve base does not exist in these 5 states.
The Sabotka study is based on a maximum of 26 states.
This was determined from an examination of the data source
for the Sabotka study.- The data source, an estimate of
I/ Report of the Interagency Coal Task Force to the FEA
Project Independence Blueprint, Bureau of Mines,
October 4, 1974.
-39-
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the reserve base on a state basis, excludes the states of
Georgia, Louisiana, Nebraska and North Carolina. In addition
to these 4 states, the Sabotka study provides no estimate
of the recoverable reserves located in the states of Alaska,
California, Idaho, Oregon and Washington. Since the estimates
in the Sabotka study are provided on a regional basis, the
exact number of states included cannot be determined. It
appears that a maximum of 26 states could have been included.
However, it is possible that the study represents less than
26 states.
The geographical parameters of the Mitre and Rieber
estimates should theoretically coincide with those of 1C 8312.
Both the Mitre and Rieber studies are directly or indirectly
based on the tonnages reported in 1C 8312. In the Mitre
report the resources/reserves are reported on a regional basis
without a precise breakdown, by state, of tonnages included
in each region. A comparison of the Mitre estimate with
1C 8312 indicates a difference of 99,497 million tons
(1,576,167 in 1C 8312 vs. 1,476,670 in Mitre). A closer
examination seems to indicate the Mitre study excluded the
states of Alaska, Georgia, North Carolina and all states in
the "Other States" category — Arizona, California, Idaho,
Louisiana, Nebraska and Nevada. The total tonnages reported
for these states in 1C 8312 is 99,495.0 million tons. The
deletion of these states would adequately explain the 99,497
million tons difference in these estimates. Therefore, it
may be concluded that the Mitre estimate is based on a total
of 26 states.
The basic estimate of resources/reserves in the Rieber
study was derived from the Mitre estimate. Therefore, the
geographical parameters are identical. The Rieber study
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specifically notes that Alaska was excluded. A comparison
of the total tonnages in the Mitre and Rieber estimates shows
a difference of 3,867 million tons (1,476,670 for Mitre vs.
1,480,537 for Rieber). However, this difference cannot be
explained by differences in geographical parameters. Instead,
this difference is due to a correction in the resource/reserve
estimate for the eastern Interior region, specifically the
state of Illinois.— With the exception of this region, the
regional estimates of the Mitre and Rieber studies are identical,
The three remaining studies set out in Schedule 23, USBM,
WVAGS, and CRA are more difficult to compare with respect to
geographical parameters. In the case of the USBM study the
questionnaire sampling technique precluded the inclusion of
counties in the six states that did not have mines with annual
production of 100,000 tons or more in 1967. Table 3-1
is a comparison of the number of counties containing coal
reserves with sulfur contents 1.0 percent or less. The counties
reported in USBM are compared to the counties listed in the
reserve base of 1C 8680-93. Column 1 identifies the states
included in the USBM estimate and column 2 sets out the number
of counties included in the USBM estimate. Columns 3 and 4,
from 1C 8680-93, respectively indicate the number of counties
having a reserve base in each state and the number of counties
having a reserve base with tonnages 1.0 percent sulfur or less
that are not included in the USBM estimate. Finally, column
5 is the estimated reserve base from 1C 8680-93 for those
counties not included in the USBM estimate.
I/ The source of the revision for the Illinois estimates
is cited as U.S. Department of Health, Education and
Welfare, Control Techniques for Sulfur Oxide Air
Pollutants, NAPCA No. AP-52, (January 1969), Table 4-2,
p. 4-11.
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TABLE 3-1
COMPARISON OF USBM REMAINING RESERVES ESTIMATE WITH
1C 8680-93 ESTIMATED RESERVE BASE
State
(1)
Alabama
Eastern Kentucky
Pennsylvania
Tennessee
Virginia
West Virginia
Total
Number of
Counties
Reported
(USBM)
(2)
8
13
12
6
5
55
Number of
Counties with
Reserve Base
(IC-8680-93)
(3)
12
33
29
18
7
A!
142
Number of
Counties with
Reserve Base
<1.0% S. Not
in USBM
(4)
1
9
10
7
2
18
47
Reserve Base
<_ 1.0% S. Not
Included in
USBM
(Million Tons)
(5)
0.59
271.19
612.60
46.72
114.07
2.422.44
3,467.61
As shown in Table 3-1, the USBM study provides an
estimate for 55 of the 142 counties containing a reserve base
in the study area. However, 47 counties in this study area
containing a 1.0 percent sulfur or less reserve base were
excluded. The coal reserve base of 1.0 percent sulfur or less
associated with these 47 counties is estimated at 3,467.6
million tons. Although the remaining reserves classification
of the USBM study is not directly comparable to the reserve
base of 1C 8680-93, this exercise does provide an insight
to the differences attributable to the geographic parameters
when compared to other studies.
The WVAGS estimate is not amenable to comparison with
other studies with respect to geographic parameters due to
the study's lack of detail. It is assumed this estimate
differs from other estimates of the recoverable reserves of
West Virginia due to factors other than geographic parameters.
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A similar problem exists in the CRA study. Since this
study is based on county estimates it is assumed that dif-
ferences when compared to other estimates are due to factors
other than geographic parameters.
3.2.2 Coal Rank
With respect to coal rank, the six studies showing esti-
mates for the total United States in Schedule 23 report that
coal of all ranks was included in the estimate. If all ranks
of coal (anthracite, bituminous, subbituminous, and lignite)
were included in each of these six studies then the total
tonnages for all ranks should be comparable. However, when
the estimated tonnages are compared by rank of coal certain
discrepancies become apparent. The lack of estimates in 1C
8680-93, Rieber and Mitre for bituminous coal and/or lignite
in California, Idaho, Louisiana, Nebraska and Nevada could
be reasonably explained by the fact that the estimate for
these areas and ranks found in 1C 8312 are resources and not
reserves. This same argument could apply to the bituminous
coal of Georgia and North Carolina.
A second reason for differences in the estimated ton-
nages by rank is the method of classification. For example,
1C 8312 reports both bituminous and subbituminous rank coal
for the state of Arizona. However, 1C 8680-93 reports only
subbituminous. Two separate studies of these reserves in
the Black Mesa Field concluded these reserves are of bitumin-
ous rank— , yet the Bureau of Mines classifies them as sub-
bituminous rank. This same problem of classification exists
in areas of the Northern Great Plains region where there is
I/ Keystone Industry Coal Manual, McGraw-Hill, Inc., 1976,
p. 545.
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no sharp distinction between lignite and bituminous rank coal.
To a lesser extent some ambiguity exists in the classification
of reserves in Virginia as bituminous or anthracite.
3.2.3 Date of Estimate
The dates of the estimates shown in column 6 on Schedule
23 encompass a time period of nine years. The earliest date
listed is January 1, 1965 for 1C 8312 and the most recent
date is that of 1C 8680-93, reported as of January 1, 1974.
Depletion of reserves due to production and mining losses
during this period has reduced reserves by a relatively
small amount. Hence, any differences among the studies due
to depletion would be minimal.
Total production of bituminous coal and lignite during
these nine years was 5,047 million tons.— Assuming that
mining losses are equal to production (50 percent recover-
ability), the total depletion of reserves due to mining
during these years is estimated at 10,094 million tons.
Comparing this figure with the largest and smallest estimate
of United States resources/reserves in column 5 of Schedule
23 yields the following.
TABLE 3-2
COMPARISON OF DEPLETION OF RESERVES TO
RESOURCE/RESERVE ESTIMATES
Depletion
As Percentage of
Estimate
0.6
5.9
Study
1C 8312
Sabotka
Estimate
(109 Tons)
1576
168
Depletion
1965-1973
(109 Tons)
10
10
I/ Bureau of Mines.
-44-
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It can be concluded from this comparison that the maximum
difference in the estimates shown in Schedule 23 attributable
to depletion is 10 billion tons or less than 6 percent.
The effects of depletion on resources/reserve estimates
are even less significant when additions to resources/reserves
are considered. These additions are a result of additional
geologic mapping, exploration and studies performed by Federal
and state agencies and private industry.
Publications of the Geological Survey— illustrate the
effects of the new information. Estimated original identified
coal resources as of January 1, 1967 and January 1, 1974 are
reported as 1,624,509 million tons and 1,770,600 million tons,
respectively. This represents a 9.9 percent increase in
seven years. A comparison of the measured and indicated
original resources in thick and intermediate seams with over-
burden less than 1000 feet indicates an even greater increase.
These resources are a crude approximation of the coal reserve
base. As of January 1, 1967, 389,882 million tons were
reported in this category. However, as of January 1, 1974
this estimate was increased to 513,474 million tons. This
represents an increase of more than 31 percent in seven
years.
Therefore, it appears that the effects of depletion on
resource/reserve estimates during the 1965-1974 period is
more than compensated for by additions to the estimates
resulting from increased geologic information.
I/ Averitt, Paul, Coal Resources of the United States,
~ Geological Survey Bulletins 1275 (1969) and 1412 (1975)
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3.3 Comparison of Studies Based Upon Resource
Classification and Estimation Criteria
The previous section has discussed those differences in
reserve/resource estimates arising from discrepancies in
geographic area, rank of coal and date of estimate. It was
indicated that these factors do not account for the major
variation in the total reserve/resource estimates shown on
Schedule-23, column 5. Therefore, it is apparent, the
major source of difference arises from the resource classi-
fication used in each study. Specifically this includes both
geologic and economic criteria, used to estimate the tonnages
in a particular resource class. If resource classification
accounts for a major portion of the discrepancies, it will
be reflected in the distribution by sulfur content, which is
in most cases, based upon the total reserve estimate.
As noted in Section 1.0 (supra) a considerable amount
of confusion and misinterpretation has arisen because of the
incorrect use of certain resource categories. This has led
to the adoption of a consistent set of resource, definitions
and classifications system by the USGS and the Department of
Interior.— In this section we will first review the
resource categories identified in each of the studies, with
respect to definitional consistency and where possible re-
classify any incorrect usage to that consistent with the
USGS/Interior System. Secondly, we will review the estimation
criteria used in the various studies, to the extent these
are set out, in order to identify discrepancies arising from
different criteria.
3.3.1 Resource Classification
Schedule 23, column 7 indicates the designation or re-
source classification of the estimates in each of the studies.
I/ See Appendix B.
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studies. There is a fair amount of diversity among the
studies — two studies (1C 8312 and USBM) purport to show
estimates for remaining reserves; one study (Mitre) purports
to show estimates of coal reserves; one study (Rieber) purports
to show estimates of coal resources; two studies (1C 8680-93
and CRA) purport to show estimates of the reserve base; and
seven studies (Sabotka, FPC, WVAGS, Rieber, Mitre, USBM) pur-
port to show estimates of recoverable reserves. With such
a diversity, it is important to examine the definition of the
resource class identified in each study and the consistency
of the definitions among the studies. The USGS/Interior coal
resource classification system will be used as a standard of
comparison. If the studies have consistently used the proper
classification then, other factors remaining equal, tonnage
estimates of like designations among the different studies
should be approximately the same.
In order to provide some intuitive feeling for the com-
prehensiveness of the various designated estimates, Table
3-3 sets out, in schematic form, the resource classification
system as presently defined.
TABLE 3-3
SCHEMATIC OF VARIOUS COMPONENTS OF COAL RESOURCE CLASSIFICATION
Coal Resource
Identified
Resource
Identified
Economic
Resource
(Recoverable
Reserve or
Reserve)
Undiscovered
Resource
Identified
Subeconomic
Resource
—| Demonstrated
Measured
Indicated]
I Inferred |
Hypothetical [
Speculative
Demonstrated
Measured
Indicated]
Inferred
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From Table 3-3 it can be seen that resource estimates
can encompass a wide variety of meanings unless specifically
delineated. While the term recoverable reserves has a more
specific meaning, some further classification is still re-
quired as to the components of the recoverable reserve that
are included. The reserve base merits a special note. By
definition, the reserve base includes the recoverable
reserve and some portion that cannot be recovered, thereby
placing it in the identified subeconomic category also.
Thus, its location in the diagram is such that it is not
directly linked to the Identified Resource as this would
imply a double counting of the resource.
Given the above consideration, the studies listed in
Schedule 23 will now be discussed with respect to defini-
tional aspects of the estimates.
3.3.1.1 1C 8680-93
As shown on Schedule 23 this study determined estimates
for the reserve base. This was defined in the study as
including identified coal resources in the measured and
indicated categories. Thus, this estimate could also be
characterized as a demonstrated reserve base estimate. As
such, the estimate includes some portion of the identified
resource that would be subeconomic. The study indicates
that the classification used is consistent with the USGS-
USBM classification system. As stated in Appendix B, the
definition of the reserve base does not specifically state
what components of Reserve Classification are to be included
(i.e., Demonstrated and/or Inferred). Apparently this is left
to the discretion of the estimator.
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3.3.1.2 1C 8312
Schedule 23 shows that this estimate is designated as
remaining reserves. The study was published before the
USGS-USBM classification system came into existence. It
should be noted that the total estimated tonnage was, in
turn, based upon USGS Bulletin 1136, supplemented by data
for Washington and Iowa, with adjustments for production and
depletion through 1964.i//
Remaining reserves are defined in USGS Bulletin 1136 as
"unmined reserves in the ground, as of the date of the
estimate and may be obtained by subtracting past production
and losses from original reserves." It is important to note
the term reserve in this context does not mean recoverable
as presently defined by the USGS (see Appendix B). Rather,
as indicated in Bulletin 1136 the term reserve excludes
undefined and unspecified total quantities of coal, but
probably includes "marginal" and "submarginal" resources.—
Given these factors the estimates should more properly be
classified as Identified Resources, as consistent with the
USGS classification system. As such, the estimate encompasses
both the demonstrated and inferred portions of the economic
and subeconomic identified resources. Intuitively, then,
this estimate should be larger than the estimates for the
reserve base.
I/ Coal Reserves of the United States - A Progress Report
January 1960, U.S. Geological Survey, Bulletin 1136, 1961,
2/ Ibid, page 13.
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3.3.1.3 Mitre
As shown on Schedule 23, the Mitre study set out
estimates for the U.S. by region. In addition, a separate
estimate was made for the Rocky Mountain region. The esti-
mates for the U. S. were classified as known reserves and
recoverable reserves, while those for the Rocky Mountain
area were classified as strippable reserves.
The study's estimate of known reserves is based upon
1C 8312. As shown above this should more properly be referred
to as identified resources.
The recoverable reserve estimate is apparently derived
from the demonstrated resource components as set out in USGS
Bulletin 1275— specifically defined as to bed thickness and
overburden depth. This estimate was not specifically
defined as the reserve base in the USGS study although it
appears to be consistent with the USGS classification system.
Accordingly, Recoverable Reserves would be consistent with
the USGS system.
2/
The estimate for the Rocky Mountain area-' was designated
as strippable reserves, and was based on a U.S. Bureau of
Mines report.-/ The strippable reserve is that portion of the
Recoverable Reserve which is amenable to strip mining. It
appears that this estimate includes only the Measured and
Indicated categories of the Recoverable Reserve.
I/ Coal Resources of the United States, January 1, 1967,
USGS Bulletin 1275, 1969, page 33.
2/ Arizona, Colorado, Montana, New Mexico, Utah, Wyoming,
North Dakota and South Dakota.
3_/ The Reserves of Bituminous Coal and Lignite for Strip
Mining in the U.S., USBM, 1970, 1C 8531.
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3.3.1.4 FPC
Schedule 23 shows that the estimate was designated as
recoverable reserves. The estimate is derived from USGS
Bulletin 1136 and 1275 plus USBM 1C 8531. As such, the
estimate is derived from the demonstrated reserve base
(i.e., includes only measured and indicated resources) and
is apparently consistent with the USGS classification system,
although the reserve base was not specifically defined.
3.3.1.5 Sabotka
Schedule 23 shows that the estimate is designated as
recoverable reserves. The estimate is based upon reserve
base estimate reported Coal Task Force report to FEA Project
Independence. The reserve base was defined in that study as
including only the demonstrated (i.e., measured and indicated)
portion of the identified resource. As such, the derivation
of the recoverable reserve component should be consistent
with the USGS classification system.
3.3.1.6 Rieber
Schedule 23 shows that the estimate in this study was
set out for resources and recoverable reserves. Rieber's
data were in turn adopted in total from Mitre. Thus, re-
sources should more specifically be categorized as Identified
Resources. Recoverable reserves more accurately reflected
the derivation from the demonstrated reserve base.
3.3.1.7 USBM
As shown on Schedule 23 this study presented estimates,
obtained from questionnaires, for remaining and recoverable
reserves. Remaining reserves are defined in the report as
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"coal remaining in the ground often deducted from original
in place reserves of all production and mining losses to
December 31, 1967." The report further states that the
estimate provided under this classification was related but
not the same as remaining reserve estimates presented in
USGS Bulletin 1275. This was attributable to sample limita-
tions and criteria for estimating reserves. Further, the
report states that the reserves reported were probably all
in the measured category since producers reported what they
expected in mine in the foreseeable future. Based upon these
comments it would appear that the estimate should more appro-
priately be classified as the Measured Reserve Base.
Recoverable reserves were defined in the study as coal
reserves that can be mined economically with present tech-
nology and equipment. These were estimated in the study by
asking producers what would be recoverable at 1967 f.o.b.
prices. Thus, it is not abundantly clear exactly what com-
prises recoverable reserves, although it could probably be
classified as measured recoverable reserves.
3.3.1.8 CRA
Schedule 23 shows that this report sets out estimates
of the reserve base. The underground reserves were based
upon Bureau of Mines 1C 8655— which defined the reserve
base consistently with USBM 1C 8680-93 (supra). Strippable
reserves were set out separately and based upon USBM 1C
2/
1C 8531— . This estimate in this report, however, is not
I/ The Reserve Base of Bituminous Coal and Anthracite for
Underground Mining in the Eastern U.S., USBM 1C 8655,
1974.
2_/ The Reserves of Bituminous Coal and Lignite for Strip
Mining in the U.S., 1C 8531, 1970.
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of the reserve base for strip mining but recoverable strip
reserves. Therefore, an inconsistency occurs between the
underground and strippable reserves estimates although
individually they are consistent with the USGS classifica-
tion.
3.3.1.9 WVAGS
Schedule 23 shows an estimate of recoverable reserves
were set out in this study. No source data were provided in
this study with respect to the recoverable reserve estimate;
hence, it was not possible to determine whether the term was
consistent with the USGS classification system.
3.3.1.10 Summary
All the studies have now been reviewed for definitional
consistency. Table 3-4 sets out a summary of the review
showing the original designation of the estimate and the re^
vised designation based upon USGS classification system.
This should reduce the semantic deficiencies among the studies
with respect to the estimates. Assuming all study estimates
to be now consistently defined, the criteria used to determine
the estimate is discussed in the next section.
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TABLE 3-4
SUMMARY OF STUDY ESTIMATE DESIGNATION
RESTATED ON A CONSISTENT BASIS
Study
Reference Original Designation
1C 8680-93 Reserve Base
Sabotka Recoverable Reserve
Rieber 1) Resources
2) Recoverable Reserves
FPC Recoverable Reserves
1C 8312 Remaining Reserves
Mitre 1) Known Reserves
2) Recoverable Reserves
WVA Remaining Recoverable Reserves
CRA 1) Reserve Base
2) Strippable Reserves
USBM 1) Remaining Reserves
2) Recoverable Reserves
N.D. = Not determined.
Modified to Be Consistent
with USGS/Interior System
Reserve Base (Demonstrated)
Recoverable Reserves
1) Identified Resources
2) Recoverable Reserves
Recoverable Reserves
Identified Resources
1) Identified Resources
2) Recoverable Reserves
N.D.
1) Reserve Base
2) Strippable Reserves
1) Reserve Base (Measured)
2) Recoverable Reserves (Measured)
3.3.2
Comparison of Estimation Criteria
Notwithstanding definitional consistency, the actual
tonnage estimate may differ due to the criteria upon which
the estimates are made. These criteria will vary among the
different categories of resources and will include assump-
tions pertaining to minimum coal seam thickness, overburden
depth, recovery rates for recoverable reserves, and strip-
ping ratio for determining Strippable resources. It is
beyond the scope of this report to analyze the reason for
the selection of specific criteria; however, the overall
criteria as set out among the different studies will be
reviewed to identify possible discrepancies.
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Now that the study estimates have been consistently
defined the comparison will group the studies according to
definitional similarity of the studies. Where a study has
two or more different types of estimates each estimate will
be discussed under the appropriate classification.
3.3.2.1 Studies Estimating Identified Resources
Three studies as shown in Table 3-4 set out estimates
for the Identified Resources: 1C 8312, Mitre, and Rieber.
The latter two studies' estimates are for the most part
based upon 1C 8312. 1C 8312 was, in turn/ based.for the most
part on USGS Bulletin 1136. The general criteria used for
the estimate in Bulletin 1136 included coal in seams 14 inches
thick and overburden depths down to 3000 feet. All three
studies are, therefore, consistent with respect to estimation
criteria.
3.3.2.2 Studies Estimating the Reserve Base
Three studies set out reserve base estimates as shown
in Table 3-4: 1C 8680-93, CRA and USBM. As noted, CRA
relied on underground Reserve Base data developed by the
Bureau of Mines in 1C 8655. These data were subsequently
included in 1C 8680-93. The criteria used to determine the
reserve base is the same for both reports and was defined
as follows in 1C 8680:
Reserve base — Include beds of bituminous coal
and anthracite 28 inches or more thick and beds of
subbituminous coal 60 inches or more thick that occur
at depths to 1,000 feet. Include also thinner and/or
deeper beds that .presently are being mined or for
which there is evidence that they could be mined
commercially at this time. Include beds of lignite
60 inches or more thick that can be surface mined —
generally those that occur at depths no greater than
120 feet. Also, it includes only coal from measured
and indicated categories of reliability.
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The USBM study of the Appalachian area is not consistent
with either 1C 8680-93 or CRA since it relates only to the
measured reserve base. No precise criteria were set out
for the reserve base. This apparently was left to the dis-
cretion of the producer answering the questionnaire. It
was pointed out in the study that "producers probably
reported less than 50 percent of the measured reserves . . .
that is, seams over 28 inches thick and under less than
1000 feet of overburden." Thus, one cannot be sure exactly
what criteria, other than that indicated by this broad state-
ment, was selected by the producer.
3.3.2.3 Studies Estimating Recoverable Reserves
Six studies - Sabotka, Rieber, FPC, Mitre, CRA, and
USBM - set out estimates of recoverable reserves, as shown
in Table 3-4. The estimates of recoverable reserves are
most variable since they involve judgements relating to
a determination of that portion of the reserve base which
can be developed given economic and technological conditions
at a point in time.
In practice, the estimation of recoverable reserves is
determined by applying a recovery factor to the reserve base
estimate. The reserve base estimate, of course, will embody
the important assumption relating to seam thickness, over-
burden depth, and stripping ratio. Differences in the
recoverable reserve estimate can, therefore, arise from
differences in the assumed recovery factor, differences in
how the reserve base is defined, and differences in the
criteria used to estimate the quantity of coal in the reserve
base. Table 3-5 compares the six studies with respect to
the aforementioned factors.
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TABLE 3-5
COMPARISON OF MAJOR FACTORS AFFECTING STUDY ESTIMATES
OF RECOVERABLE RESERVES
Study
Reference
Mitre
FPC
Sabotka
Rieber
USBM
Reserve Base-
Definition
Reserve Base-
General Estimation Criteria
Overburden Minimum Seam
Depth Thickness
Bitum- Subbit.-
inous Lignite
Demonstrated—
1000'
42"
Demonstrated
plus some Inferred
Demonstrated
Not defined
Same as Mitre
Measured
NR = not relevant
JY Presumed, not specifically defined in study.
"2J Estimated, not specifically stated in study.
J/ Strippable recoverable reserves only.
10'
1000'
1000'
120'
1000'
28"
28"
28"
28"
5'
5'
NR
NR
Recovery Factor
Used to Estimate
Recoverable Reserves
50% underground
60% strip-Appal. &
Interior
80% strip-Rocky Mt.
50% -(
40% underground
70% strip
Not given
Based upon producers'
judgement
For the most part the criteria utilized with respect to
the reserve base are fairly consistent. This arises primarily
from the fact that the USGS data were in most instances the
primary source of information. The Mitre study criteria was
based upon USGS Bulletin 1275, and is more restrictive than
the other studies.
Most of the variation occurs in the recovery rates as-
sumed in the different studies where this parameter was given.
The average recoverability rate for the Mitre study is 63 per-
cent which probably compensates for the more restrictive
reserve base criteria. The FPC study did not specifically
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indicate how the recoverable reserves were calculated. The
50 percent shown in Table 3-3 is a very generalized estimate
based upon a comparison of the recoverable reserve estimate
developed in the study to the source estimate shown in USGS
Bulletin 1275. The Sabotka study average recoverability
factor is 55 percent. The derivation of the recoverable
reserves was based upon the reserve base developed by the
Coal Task Group for FEA Project Independence. While the
criteria for the reserve base estimation is consistent with
the other studies, except Mitre, the lower assumed recovery
rates would tend to lower the estimate of underground re-
coverable reserves and strippable recoverable reserves. The
Rieber study base data are the same as the Mitre study. The
remaining studies (CRA and USBM) are not comparable with the
other studies due to the difference in geographic area, and
absence of specific estimation criteria.
Schedule 24 sets out a comparison of the estimates in
the Sabotka, Mitre, FPC study on regional basis showing the
reserve base data, and the recoverable reserve data. The
data have been adjusted where necessary to make all regions
comparable. The Sabotka estimate of total recoverable re-
serves is lowest. The apparent reason stems from two factors.
First, the recovery rates assumed tend to bias the entire
regional estimation downward. This is particularly true for
the underground reserve base which is larger than the strip-
pable reserve base and accordingly reflects the effect of
the 40 percent recovery rate in the recoverable reserve
estimate. Second, in the Northern Plains region underground
reserves have been excluded. This exclusion would account
for 37 billion tons using Sabotka's assumed recovery rate,
and is, therefore, the most significant discrepancy. Finally,
no estimate was made for the West Coast, although, this would
account only for minimal differences.
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The Mitre study estimate of recoverable reserves is
higher than the Sabotka estimate, primarily because of the
inclusion of underground reserves in the Northern Plains
region and the higher assumed recovery rates. It is impor-
tant to note, however, that the reserve base is smaller in
the Mitre study. This is accounted for by the more restric-
tive criteria used in estimating the reserve base.
The FPC recoverable reserve estimate in aggregate
appears consistent with the other studies. However, it is
not clear exactly how the estimate was derived since no
information was provided with respect to recovery rates.
While the source of information and criteria for the re-
serve base was identified, the specific data could not be
determined. Certain discrepancies between the FPC and other
studies appear in the regional breakdown of the estimate.
First, the Eastern region recoverable reserve is signifi-
cantly higher than other studies. The reserve base criteria
defined in the FPC study is the same as that for the reserve
base in the Sabotka study. Thus, using the reserve base for
the Eastern region as shown on Schedule 24, and assuming
recovery factors of 50 percent for underground and 70 per-
cent for strip results in a recoverable reserve estimate of
59 billion tons. This number should be close to the FPC
estimate for the Eastern region; however, it is not.
Secondly, the recoverable reserve for the Northern Plains
region supposedly includes both underground and strippable
reserves; however, the estimate is smaller than the Sabotka
estimate for the region which as noted includes only strip-
pable reserves. Thus, there appears to be some inconsistency
in the derivation of the FPC data on a regional basis; how-
ever, insufficient information was provided in the report
to delineate the source of these inconsistencies.
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Finally, it should be noted that the consistency of
the recoverable reserve estimate in relation to 1C 8680-93
can be checked through the reserve base estimates. Schedule
23 shows the total reserve base estimate in 1C 8680-93 as
436 billion tons. Comparing this estimate with the esti-
mates shown on Schedule 24 indicates a relatively close
agreement among total estimates. The reserve base for the
Mitre study is somewhat lower due to the more restrictive
criteria used, as previously discussed.
3.4 Comparison of Reserve/Resource Estimates Based
Upon Sulfur Redistribution
The previous sections have discussed factors other than
sulfur content that account for differences among the dif-
ferent studies. Accordingly, it is now possible to concentrate
solely on the sulfur distribution of the reserve/resource
estimates. For the most part, reserve/resource estimates by
sulfur content could be described as an allocation of total
reserve/resource estimates based upon available sulfur data.
Thus, two independently obtained sets of data — reserve/
resource estimates and sulfur data — are combined through
some type of allocation procedure.— Due to this procedure
discrepancies identified previously will carry through to
the distribution by sulfur content.
Schedule 23, column 11, sets out a comparison of
reserve/resource estimates at 1.0 percent sulfur or less,
thereby providing an indication of the differences among
the studies. Of course, these differences are in part due
I/ Only the USBM Survey of Appalachian Producers may be
different since measured resources by sulfur content
were estimated simultaneously by the producer-
respondent.
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to the factors previously discussed in the other sections.
In addition, all of the estimates shown in column 11 of
Schedule 23 are not completely comparable since some of the
estimates are expressed in terms of pounds of S02 or sulfur
per million Btu of heat input. Where the reserve/resource
estimates have been so expressed, the common delineation for
low sulfur coal is the NSPS standard of 1.2 pounds S02/MMBtu
(0.6 Ib. SO_/MMBtu). For the other estimates the 1.0 percent
sulfur level was selected since it appears to be common to
all the studies. Column 10 of Schedule 23 which sets out
data pertaining to the calibration of reserve/resource esti-
mate by sulfur content, shows there is considerable diversity
among the range and intervals employed. This makes an inter-
study comparison difficult for reserve/resource estimates less
than 1.0 percent sulfur, and, therefore, precluded such an
analysis.
The comparison will proceed as follows: First, the
sources of data utilized to determine the sulfur content are
examined. Second, the allocation procedure for each study
is analyzed.
3.4.1 Data Sources
The sources of data used to determine the sulfur content
of coal reserve/resource estimates are of significance since
they form the basis for allocating the total estimates on
either a sulfur content or emissions basis. Column 12 of
Schedule 23 shows the sources of sulfur data utilized in each
of the studies. Close observation reveals that all of the
studies except USBM have relied for the most part on the same
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sources of data for coal sulfur content. These data are
comprised of samples routinely collected for the purpose of
testing coal purchased under contract specifications by the
U.S. Government. Such sample data, as pointed out in the
summary of 1C 8680-93, in Section 2.0, date back to the first
decade of the century and have over the last thirty years
been published for each fiscal year.—
That these data are the common source of information
relating to sulfur content can be determined by first observ-
ing that the data were first utilized in 1C 8312. 1C 8312
was in turn directly utilized in Mitre, and Rieber as the
basis for the distribution of reserves by sulfur content.
Sabotka relied on the Mitre study and, therefore, indirectly
used 1C 8312. Secondly, the sulfur distributions in 1C 8680-93
are based upon the Bureau of Mines data bank which apparently
consists primarily of the U.S. Government sample analyses.
The CRA report relies on an earlier USBM report 1C 8655 which
utilized the same data bank. As noted in Section 2.0, 1C 8655
is subsumed under 1C 8680-93. The West Virginia report relied
on a 1940 study conducted by Headlee and Nolting in addition
to U.S. Government purchase information. Finally, while no
data source information was provided in the FPC report it is
believed that 1C 8312 was utilized based primarily on the
fact that Mr. DeCarlo was part of the task force that prepared
the report. As noted, the only study which apparently devel-
oped independent data on sulfur content was the USBM survey of
Appalachian coal producers since this relied on the producers'
determination of the sulfur content of their reserves.
I/ Usually published under the title "Analysis of Tipple
and Delivered Samples of Coal Collected During the
Fiscal Year . "
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The fact that U.S. Government sample data have
essentially formed the basis upon which reserve/resource
estimates by sulfur content raises an important question.
How representative of domestic reserves and/or resources
are these data? The specific answer to this question is
beyond the scope of this report; however, some observations
can be made based upon a brief analysis of the government
data. This analysis, set out in Appendix C, while by no
means comprehensive, does permit the following observations.
First, while these data provide a lengthy historical
record, a question is raised as to the applicability of
such data to current reserve/resource estimates. The point
here being that depletion of seams in some areas for which
data were obtained early in the century may lead to ques-
tionable results. One such example occurs in 1C 8680-93,
with respect to 'the reserve base estimate for Illinois and
Indiana. It was determined that the sample analysis data
used to distribute the reserve base estimates by sulfur
content did not accurately reflect the current sulfur con-
tent of the reserve base. Thus, estimates were developed
independently based primarily upon the judgement of persons
familiar with the reserve base in these states. In our re-
view of the various studies in this report we have not come
upon any attempt to verify the representation of this
historical data.
Second, and somewhat related to the first point, there
is a basic implied'assumption which underlies the use of
the sample data. This is the assumption that the coal
characteristics data obtained from the coal produced are
approximately the same as coal in place. While this would
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appear intuitively plausible, the applicability should be
limited to estimates of recoverable reserves and more gen-
erally to estimates of the reserve base. The reason being
that the sample data are collected from coal already pro-
duced, which specifically represents recoverable reserves
but also the reserve base by definition. The validity of
applying such data to the resource category, therefore,
appears less plausible. Again, we are not aware of any
research relating to the validity of the data's application.
Third, it appears that some bias may have been introduced
in the sulfur distribution of reserves due to the sample data.
This stems from the fact that, over time, Government coal
purchases have represented only a small portion of total pro-
duction (see Appendix C) and may have been comprised of what
could be referred to as premium type coals. That is, coal
which has been sized and cleaned in addition to run of mine
coal from high quality seams. This coal will, on average,
probably have a lower sulfur content and higher Btu content.
As pointed out in Appendix C, this would tend to bias the
sulfur distribution relative to one obtained primarily from
raw .coal samples.—
In summary, while the Government purchase data appears
to be the most extensive record with respect to coal charac-
teristics, we believe the potential weakness cited above is
significant enough to warrant further in-depth research.
I/ Apparently the Bureau of Mines used only raw coal samples
~~ in developing the sulfur distributions in 1C 8680-8693.
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Finally, as noted above, the USBM survey of Appalachian
producers relied on the responses of the producer to estimate
the sulfur content of reserves. No information is provided
in the report as to how the producers estimated the sulfur
content of reserves (i.e., based upon core samples or produc-
tion data); thus, we are unable to comment on this study.
3.4.2 Allocation Procedures
The previous section has shown that all of the studies
except USBM have relied upon the same sources of data for
sulfur content. It now remains to examine how these data
were utilized to allocate the reserve/resource estimates by
sulfur content. On this point of comparison we found little
to actually analyze since there is little documentation of
the allocation procedures. We find that the distributions
set out in 1C 8312 and 1C 8680-93 have been used in other
studies shown in Schedule 23 with the exception of USBM, WVA
and the estimate of Rocky Mountain strippable reserves in
Mitre. Generally, the procedure employed a computation of a
percentage distribution based upon the sample data, or sulfur
distributions set out in other studies, which were then
applied to the total reserve/resource estimate. The only
exception appears to be 1C 8680 and 8693 which used a proba-
bility distribution for estimation purposes.
A comparison of the study estimates by sulfur interval
was not .undertaken due to the differences among studies with
respect to the use of sulfur intervals plus the fact that •
several of the studies set out estimates in terms of emis-
sions. It is believed that the assumptions and interpolations
required to adjust all studies to some type of comparable basis
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would detract more than add to an understanding of deficiencies
in the studies. We have opted instead to discuss the alloca-
tion procedure for each study separately. Before beginning,
it is important to note that for the most part we have found
that the factors previously discussed account.for the major
differences among the studies, with the allocation process
accounting for a smaller portion of the.difference. This, of
course, stems from the reliance on the same data sources and
the adaption of distributions developed in other studies, as
previously cited.
3.4.2.1 1C 8680-93
The procedures used to allocate the reserve base esti-
mates by sulfur content differ between 1C 8680 (Eastern U.S.)
and 1C 8693 (Western U.S.) apparently due to insufficient
sample data for Western U.S.
For the Eastern U.S. the report states that based upon
72,000 coal analyses, using the sulfur analyses as data
points for constructing a distribution curve, the coal re-
serves were through statistical probability distributed by
sulfur category. No tonnages were allocated to sulfur
intervals higher or lower than these observed. In addition,
seams were classified as unknown where no or little data
existed. For Illinois and Indiana a judgemental allocation
was used, in addition to the statistical distribution proce-
dure.
The report provides no documentation as to how the type
of probability curve was constructed. In addition, no infor-
mation is provided with respect to standard errors of the
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estimate or statistical confidence intervals. Without such
information it is impossible to appraise the validity of the
results. It would be most useful if such information were
developed by the Bureau of Mines. The Bureau of Mines ADP
personnel in Denver were contacted with respect to program
documentation; however, it was stated that while there are
plans to publish the procedures nothing was available at the
time.i/
For the Western U.S. the allocation of the reserve base
by sulfur content was determined by applying a weighted aver-
age of all available sulfur sample values (on a dry basis)
for individual beds. Approximately 20,000 samples were used.
Beds were classified as unknown where no analyses were avail-
able. The report adds the important caveat that:
"Tonnages subdivided by sulfur levels are based
in some instances on older coal samples. Therefore,
coal of a particular sulfur level in the tables may
nowiactually be depleted."
This tends to cast some doubt upon the allocation pro-
cedure used with respect to the Western U.S.
Thus, the allocation procedures between the studies are
inconsistent. The approach used for the Eastern U.S. appears
conceptually to be the proper approach, while the Western U.S,
approach does not appear supportable on statistical grounds.
Both approaches are of course subject to the limitations of
the data base cited in Section 3.4.1. Finally, one report,
I/ Telephone contact with Mr. J. Tolin, USBM AD.P Facility,
Denver, Colorado.
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1C 8680, purports to use raw coal samples for sulfur distri-
butions while 1C 8693 indicates that sulfur content on a dry
basis was used. This is of great significance with respect
to Western subbituminous and lignite coals where moisture
content can account for as much as 40 percent of the coal
weight. The effect would be to shift these higher moisture
coals to higher sulfur intervals.
Given these potentially serious shortcomings of the
Bureau of Mines procedure, one could strongly suggest that we
do not know with significant certainty what the sulfur distri-
bution of the reserve base is. In addition, since this
analysis is one of the most detailed to date, the same comment
would apply to all of the other studies shown on Schedule 23.
3.4.2.2 1C 8312
This report gives no detailed documentation of how the
resource estimates were allocated by sulfur content. Appar-
ently, simple averages were used to characterize a coal bed
where more than one sample was available. If no analyses
were available other unidentified sources were used to
determine sulfur content. Finally, it is important to note
that in most instances washed coal samples were used.
The effect of using clean coal samples, taken together
with the assumption of simple averaging would probably tend
to bias the sulfur distribution towards the lower sulfur
intervals. This bias is probably accentuated by the fact
that allocation procedure was applied to identified resources,
which includes coal occurring at depths of up to 3000 feet;
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thereby including coal which probably has never been produced
and perhaps never sampled. For example, lignite resources
occurring at depths of up to 2000 feet are included in the
less than 1.0 percent sulfur interval.
In addition to the above, the sulfur content for Illinois
coal was stated at lower intervals (less than 2.0 percent)
than subsequent reports estimated. This, of course, would
also contribute to downward bias of sulfur content.
3.4.2.3 Mitre
The Mitre study allocation of resources and recoverable
reserves as shown on Schedule 5 was based on the percentage
distribution developed in 1C 8312 and is, therefore, subject
to the same deficiencies as previously discussed.
For the sulfur distribution with respect to Rocky Mountain
strippable reserves a separate computation was developed using
approximately 1900 analyses consisting primarily of U.S.
Government purchase data samples. The distribution was
determined by the number of samples in each sulfur interval
(see Schedule 6). The samples were used to characterize
coal regions. Furthermore, the sulfur contents were reported
on a dry basis.
The allocation process for the Rocky Mountain coal is
primarily dependent upon the adequacy of the sample analysis.
The shortcomings of.. the data have been previously discus.sed.
In addition, the simple percentage distribution allocation
would appear to have major shortcomings when used to char-
acterize coal regions which may be comprised of a number of
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seams. Finally, since the sulfur content is shown on a dry
basis, this will tend to bias the sulfur content upward, and
may not accurately reflect in place coal reserves.
3.4.2.4 Rieber
This study adopts the sulfur distribution of resources
and recoverable reserves developed in the Mitre study,
modified for the upward revision in the sulfur distribution
of Illinois coal. This provided the basic source of data
for the adjustments made on comparable but effective sulfur
basis. Thus, the entire analysis is subject to the biases
previously cited with respect to 1C 8312 except with respect
to the Illinois coal.
Several additional comments are in order with respect
to the adjustments made in the Rieber study since the sulfur
distribution is further altered by these adjustments.
Overall the restatement of reserves on a comparable Btu and
effective sulfur basis provides one means of consistently
determining the sulfur content across different ranks of
coal that will meet emissions limitations. However, the
changes which occur on a tonnage basis are more apparent
than real and as such give a somewhat misleading indication
of reserve and resource position.
The major weakness of the adjustment is the selection
of a common heat content which can affect the results sig-
nificantly. For coals lower than the selected heat content
the adjustment will lower the tonnage, while an increase in
tonnage will result for coal in higher heat content. The
effect on sulfur distribution will be just the opposite for
the lower and higher heat content coals. A wholly comparable
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and perhaps more effective approach would be to state reserves
in terms of emissions rather than sulfur content. This avoids
the last step of calculating an effective sulfur content and
also provides for a much more meaningful and straightforward
interpretation of the data.
3.4.2.5 Sabotka
The Sabotka study as shown on Schedule 23 relied on the
Mitre study for the distribution of sulfur content in all
regions except the Northern Plains where data were published in
Coal Age Magazine.— The distribution of recoverable reserves,
however, have been stated in terms of emissions (Ib. SO^/MMBtu).
The distribution is, of course, subject to the problems
discussed under 1C 8312. The conversion to an emission
basis was developed by interpolating the Mitre data at that
sulfur content which would meet the emissions intervals
selected by Sabotka. This adjustment required an assumption
concerning the heat content of the coal. In the East, for
example, it appears that a 12,000 Btu/lb. heat content was
assumed; however, it was not possible to determine what Btu
value was assumed for the other regions.
3.4.2.6 CRA
The CRA report adopted, as shown on Schedule 23,
column 12, the Bureau of Mines data presented in 1C 8655.
The estimates by sulfur content were in turn presented in
terms of emission categories, including a breakpoint for
I/ These publications apparently were used for Montana
and Wyoming since little or no analyses were provided
for the other states in the Northern Plains region.
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NSPS coal. As noted previously, this study is subsumed
under 1C 8680. It is accordingly subject to the problems
discussed for that report.
A different approach was used to estimate strippable
reserves. Here an approach utilizing the average relation
of heat and sulfur content based on the underground reserve
base was used to distribute strippable reserves by sulfur
content. A weakness in this approach is that the seams
included in the strippable reserve may differ from the under-
ground reserve. Therefore, the distribution will be biased
with respect to the underground reserve base.
3.4.2.7 WVA
This report, as shown in column 12 of Schedule 23, is
based on a report published in 1940 by Headlee and Nolting.
This report included the data obtained from U.S. Government
purchase information discussed above and is, therefore,
subject to the weaknesses inherent in the data. In addi-
tion, it appears the technique relied on a simple averaging
of the data points to determine the contour maps. Therefore,
it would appear that the analysis may be biased towards the
characteristics of those coals where most of the sampling had
occurred.
3.4.2.8 USBM
This study developed the distribution of reserves by
sulfur content for the Appalachian region based upon the
responses of 701 large producers (production greater than
100,000 TPY). As such, it provides perhaps the only
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independent analysis of the distribution of reserves by
sulfur content. Since little or no information was provided
with respect to the sample selection or questionnaire, it
is impossible to comment on the sulfur content estimates.
Based upon a comparison of the reserve base data for the
state of West Virginia in the USBM study and that presented
in 1C 8680 adjusted for unknown volumes, it appears that,
other than for differences attributable to geographic and
reserve definition, the relative amount of coal reported at
less than 1.0 percent sulfur is smaller than that shown in
the 1C 8680. This may indicate an overstatement of low sulfur
coal based upon the distribution system used in 1C 8680.
3.4.2.9 FPC
The task force report as noted on Schedule 23, column
13 apparently based the sulfur distribution of recoverable
reserves upon straightforward percentage distribution derived
from 1C 8312. A comparison of the distribution developed in
1C 8312 with those developed from the FPC report indicates
almost complete comparability. Accordingly, the sulfur
distribution of recoverable reserves in the FPC report is
subject to the caveats pointed out with respect to 1C 8312.
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4.0 A RESTATEMENT OF U.S. BUREAU OF MINES RESERVE BASE
ESTIMATES IN TERMS OF POTENTIAL SO EMISSIONS
4.1 Introduction
The previous sections of this report reviewed and
analyzed various studies which have set out coal reserves
and/or resource estimates by sulfur content. The purpose of
such estimates is primarily to determine the potential for
compliance with air quality regulations relating to S02
emissions. In most of these studies, however, the distinc-
tion between sulfur content and S0» emissions has not been
explicitly accounted for which has, in some instances, led
to a misinterpretation of the reserve position of compilable
coal. If the objective of studies of coal supply and/or
reserves by sulfur content is to determine S02 compliance
potential, then a more appropriate format would be to set
out the data in terms of potential S0_ emissions.
In this report, we have attempted to accomplish such a
restatement using as a basis the Bureau of Mines reports
1C 8680 and 1C 8693. To date we are not aware of any attempt
by the Bureau of Mines to compute such distribution of
reserves by S02 emissions. Certainly, such a conversion
would appear wholly adaptable to the data processing system
maintained by the Bureau. It should be noted that the
Bureau of Mines data were selected since they are the most
detailed and comprehensive estimate of the U.S. reserve
base. While we initially considered performing the same
restatement for the other studies reviewed, it was finally
decided to concentrate our efforts on Bureau of Mines data.
The reasons for this are threefold. First, as stated pre-
viously, the data base of the USBM .s.tudy was in .sufficient
detail to permit a meaningful distribution. Such a dis-
tribution could not be accomplished in most of the other
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studies due to the aggregation over various sulfur inter-
vals. Second, the inconsistencies in terms of tonnage among
the various studies reviewed would for the most part, result
in a similar type of redistribution on an emission basis.
Thus, it was believed that no overall gain in understanding
would result. Third, the attempt to restate the reserve
base on an emission basis was viewed primarily as a proto-
type analysis since time and budgeting constraints did not
permit a greater level of detailed analysis. As such, the
analysis could probably be modified and upgraded, and
subsequently applied to other studies if desired.
The sections that follow will discuss the basic method-
ology, the results, and the shortcomings of the analysis.
Finally, it is emphasized that while we feel the results of
the analysis provide a useful alternative for depicting
reserve data, they should not be taken as the definitive
effort since improvements in the methodology can be made.
4.2 Methodology
4.2.1 Selection of S02 Intervals
The first step in the transformation procedure was to
select the increments of a new distribution in terms of
pounds of S02 per million Btu. The intervals selected
correspond to the sulfur intervals used in the Bureau of
Mines estimates, converted to pounds of SO- per million Btu
assuming a heat content of 12,000 Btu per pound. The
reasons for this choice of intervals are .(1) these intervals
provide a constant transition from the Bureau of Mines esti-
mates, and (2) .it appears .to be a common practice in .the
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coal industry to assume a 12,000 Btu per pound heat content
with respect to the ability of coals to comply with a
particular emissions regulation. The following is a compari-
son of Bureau of Mines intervals and the transformation used
in this study:
TABLE 4-1
TRANSFORMATION OF SULFUR INTERVALS TO POUNDS OF
S02 PER MILLION BTU INTERVALS AND POINT ESTIMATE
Transformation to
USBM Sulfur Intervals Pounds of S02 Per Midpoints, Pounds of S02
(Percent Sulfur by Wt.) Million Btu 1' Per Million Btu I/
£0.45 £0.75
0.46 - 0.65 0.76 - 1.08 0.92
0.66 - 0.85 1.09 - 1.42 1.25
0.86 - 1.05 1.43 - 1.75 1.59
1.06 - 1.45 1.76 - 2.42 2.09
1.46 - 1.85 2.43 - 3.08 2.75
1.86 - 2.25 3.09 - 3.75 3.42
2.26 - 2.65 3.76 - 4.42 4.09
2.66 - 3.00 4.43 - 5.00 4.71
> 3.00 > 5.00
I/ Assuming heat content of 12,000 Btu per pound.
It should be noted that the values in the first column
are not entirely consistent with those reported by the
Bureau of Mines. The actual Bureau of Mines intervals are
£ 0.4, 0.5-0.6, 0.7-0.8, etc. This assumption was necessary
to prevent interval gap problems in the transformation.
4.2.2 Redistribution of Reserve Base Data by
SO- Level
The redistribution of the reserve base estimates in
terms of S0? emissions required data as to heat content anc
sulfur content. The redistribution of the Bureau of Mines
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estimate was performed on a state by state basis using the
tonnages reported in 1C 8680 and 8693. Due to a lack of
information on the sulfur content and/or heat content
certain reserves reported by the Bureau of Mines were clas-
sified as an unknown entity. Thus, the total tonnages of
the reserves distribution by SO- level has been reduced. It
could be assumed that the tonnages reported with an unknown
sulfur content are distributed in the same proportions, by
sulfur content, as the reserves with known sulfur content.
This assumption was considered too heroic and, therefore,
not used.
In most cases the Bureau of Mines reports the average
analyses of coal by state, county and coal seam. The
weighted average heat content for each rank of coal by state
from these analyses was used in the conversion of coal
tonnages on a state basis to a pounds of S02 per million
classification. As mentioned previously, analyses for some
reserves were not available in the Bureau of Mines report.
In these instances other sources were consulted for estimated
average coal heat contents.—' When no published estimate of
the average heat content could be found, these reserves were
deleted from the distribution. The following table summarizes
the tonnages deleted from the distribution due to a lack of
information.
Primarily, Keystone Coal Industry Manual, McGraw-Hill,
Inc., 1976. and L. Hoffman et. al., Survey of Coal
Availabilities by Sulfur Content, The Mitre Corporation,
MTR-6086, May 1972.
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TABLE 4-2
TONNAGES DELETED FROM SO DISTRIBUTION (MILLION TONS)
Reason for Deletion
Lack of Sulfur Content
739.91
39,465.99
5,377.54
2,985.10
48,568.54
Lack of Heat Content
126.44
—
—
296.00
422.44
Total
866.35
39,465.99
5,377.54
3,280.10
48,990.98
Rank
Anthracite
Bituminous
Subbituminous
Lignite
Total
Of the 436,725.30 million tons of reserves reported
in 1C 8680 and 1C 8693, 48,990.98 million tons (approxi-
mately 11 percent) could not be included in the distribution
due to a lack of information. Less than one percent was
deleted due to insufficient information on the heat content
of the reserves.
The transformation of the Bureau of Mines reserve
base data consisted of first, determining the S02 interval
midpoints from the Bureau of Mines report as shown in
Table 4-1, and second, restating the tonnage estimates
in terms of pounds of S0_ per million Btu based upon the Btu
and sulfur data. These data were then computer processed to
obtain a plot of both a frequency distribution and a cumula-
tive plot.
Since sulfur has an atomic weight of 32 and oxygen
an atomic weight of 16, the weight of the SO- molecule
is equally composed of sulfur and oxygen. Therefore, the
S0_ emissions released when coal is burned would be twice
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the sulfur content, by weight.— As an example, coal with
a sulfur content of 0.72 percent by weight and a 12,000 Btu
per pound heat content would be converted to the equivalent
pounds of SO per million Btu category as follows:
Pounds of SO,/MMBtu: (2) ft (0' 12J** ^ S"lfur)
2 0.012 MMBtu/Pound
Pounds of SO /MMBtu =1.2
Chart 1 illustrates this relationship among sulfur
dioxide emissions, sulfur content, and the calorific content
of coal.
In restating the reserve base on an SO., basis minor
&
difficulties were encountered at the first and last cate-
gories of the S00 distribution, since these intervals
contain reserves classified as "less than or equal to"
and "greater than" a specific value and are therefore open-
ended. This problem is due to the imperfect transition from
the Bureau of Mines sulfur intervals to a midpoint estimate
2/
of SO- emissions.— The average heat content of this coal,
as reported by the Bureau of Mines, is 13,280 Btu per pound.
I/ It should be noted that the calculation of Ibs. SC>2/MMBtu
were based upon the assumption of 100 percent conversion
of S to SC>2 and not the 95 percent normally assumed for
S02 and the 98 percent assumed for SO .
2_/ These shortcomings are attributable to (1) attempting a
~~ redistribution on summary data and not the basic data
used in 1C 8680 and 1C 8693, and (2) limited capacity
of the available computer facilities with respect to
continuous frequency distributions.
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In redistributing the reserves estimates on an S0? basis,
it was necessary to treat the Bureau of Mines sulfur intervals
as point estimates. The result is that throughout the entire
redistribution a portion of the reserves that should not
have been redistributed were in fact assigned to an adjacent .
\
category and vice versa. However, on the average, the
redistribution will approximate the true distribution which
could be obtained from the Bureau of Mines data base used in
the preparation of 1C 8680 and 1C 8693.
4.2.4 Comparison of Reserve Base Distributions
Schedule 25 is a comparison of the Bureau of Mines
distribution based on percent sulfur content with the
redistribution obtained on a pounds of S02 per million Btu
basis. Aggregating all ranks of coal for the total United
States shows that the net effect of the redistribution
is to shift the reserves toward the center of the dis-
tribution. When restated on a pounds of S0~ per million
Btu basis the aggregation of all coal ranks is more mean-
ingful than an aggregation based on percent sulfur only.
This restatement takes into account both the percentage
sulfur content and the heat content of the coal and permits
a direct comparison with emissions regulations stated in
terms of pounds of SO,, per million Btu.
This shift is shown in Charts 2 through 6. These
graphs illustrate the weakness in assuming a constant heat
content from all coal. The percent sulfur distribution, as
shown by the dashed line in each chart, would identify those
reserves capable of compliance with sulfur emissions regula-
tions (in terms of S02 emissions) only if all reserves had a
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heat content of 12,000 Btu per pound. However, the heat
content of coal is variable. When these variations in heat
content are introduced, the resulting distribution, as shown
by the solid line in each chart, yields a more accurate
comparison of the ability of coal reserves to meet sulfur
emissions standards.
As would be expected, the shift in the distributions
are most predominant in subbituminous and lignite reserves
(see Charts 5 and 6). These shifts result from the lower
heat content characteristic of these coals. More than 86
percent of the United States subbituminous coal reserves are
located in Montana and Wyoming. The average heat content of
the reserves located in these states are 8,700 and 9,400 Btu
per pound, respectively. Similarly, North Dakota and
Montana contain approximately 86 percent of the United
States lignite reserves with respective average heat contents
of 7,030 and 6,600 Btu per pound. These lower heat contents
result in an even more dramatic shift to the higher sulfur
ranges as shown in Chart 6.
The redistribution of anthracite reserves in terms of
pounds of S0_ per million Btu only slightly alters the
£
distribution according to percent sulfur by weight (see
Chart 3). This is explained by the fact that the anthracite
reserves which are essentially limited to Pennsylvania (more
than 97 percent), have an average heat content of approximately
12,500 Btu per pound.
The net effect of the redistribution of bituminous coal
reserves on a national basis is a slight increase in the
quantity of reserves in the intervals 5.00 pounds of S0~ per
million Btu or less. This increase, to a large extent is
attributable to the Appalachian coal reserves in eastern
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Kentucky, Pennsylvania and West Virginia. These coals are
generally low-to-medium sulfur content coals and the average
heat contents of bituminous coals in these states all exceed
13,000 Btu per pound.
Bituminous coal reserves in the Mid-Continent and Western
United States effectively cause the distribution to shift to
higher sulfur ranges. This is due to the large amount of
coal containing heat contents of 12,000 Btu per pound or
less. In fact, the only states in the Mid-Continent region
possessing substantial amounts of reserves with average heat
contents significantly greater than 12,000 Btu per pound are
Colorado (12,520) and Utah (12,660).
4.3
Reserve Base Distributions by SO,, Level on a
Regional Basis
Charts 7 to 21 show the United States coal reserve base
on a regional basis, by rank of coal, expressed in terms of
SO- emissions. The states included in each region are as
follows:
TABLE 4-3
GEOGRAPHICAL COAL RESERVES REGIONS BY STATES
Northern
Appalachia
Maryland
Pennsylvania
West Virginia
Southern
Appalachia
Alabama
Georgia
Kentucky
(east)
North Caro-
lina
Tennessee
Virginia
Mid-
Continent
Arkansas
Illinois
Indiana
Iowa
Kansas
Kentucky
(west)
Louisiana
Michigan
Missouri
Mississippi
Nebraska
Ohio
Oklahoma
Texas
Far
Western Western
Arizona Alaska
Colorado California
Montana Idaho
New Mexico Nevada
North Dakota Oregon
South Dakota Washington
Utah
Wyoming
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Although Ohio could be considered a Northern Appa-
lachian state, it was included in the Mid-Continent category.
This is because the physical characteristics (sulfur and
heat contents) are more comparable to the Mid-Continent
of states such as Illinois and Indiana. In 'the case of West
Virginia, counties in the northern part of the state— are
frequently aggregated in Northern Appalachia while the
2/
southern counties— are included in Southern Appalachia.
Bureau of Mines 1C 8680 and 1C 8693 does not distinguish
between northern West Virginia and southern West Virginia;
therefore, the entire state was included in Northern Appa-
lachia.
In Charts 7 to 21 the scale of the vertical axis is
varied from region to region to facilitate visual interpre-
tation. The intervals on the horizontal axis are those
intervals shown on Schedule 24 in terms of pounds of S02
per million Btu. In each figure both the frequency dis-
tribution and the cumulative distribution are shown. The
vertical line through 1.09-1.42 interval represents the 1.2
pounds of SO- per million Btu new source performance standard,
To comply with this standard, coal to the right of this line
cannot be burned unless .it is blended with coal in that
portion, of the distribution to the left of the line. Then,
the weighted average sulfur level of the resulting blend
would be limited to 1.2 pounds of SO- per million Btu or less.
"I/ Bureau of Mines Producing Districts 3 and 6
2/ Bureau of Mines Producing Districts 7 and 8
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4.3.1 Anthracite Reserve Base
A comparison of Charts 7 and 8 shows that the reserve
base of anthracite coal in the United States is essentially
limited to the Northern Appalachian region. Specifically,
more than 97 percent of the total anthracite reserves are
located in Pennsylvania. With respect to sulfur content,
these reserves are distributed as follows:
TABLE 4-4
DISTRIBUTION OF UNITED STATES ANTHRACITE COAL RESERVE BASE
BY SULFUR CONTENT
(Million tons)
Sulfur Content
(pounds SO./MMBtu) Frequency Cumulative
< 0.75 158.93 158.93
0.76 ~ 1.08 1,188.33 1,347.26
1.09 - 1.42 2,837.36 4,184.62
1.43 - 1.75 2,149.53 - 6,334.15
1.76 - 2.42 166.74 6,500.89
2.43 - 3.08 16.15 6,517.04
3.09 - 3.75 0 6,517.04
3.76 - 4.42 0 6,517.04
4.43 - 5.00 0 6,517.04
> 5.00 0 6,517.04
For illustrative purposes and assuming the reserves
are evenly distributed within the intervals, 2,198.47
million tons, or approximately 33.7 percent of the total
anthracite reserves could meet the 1.2 pounds per MMBtu
regulation. It should be noted that these figures exclude
866.35 million tons of anthracite reserves deleted due to
lack of information on sulfur and/or heat contents. The
majority of these deleted reserves (654.95 million tons)
in Pennsylvania were anthracite reserves of unknown sulfur
content.
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4.3.2 Bituminous Reserve Base
The total United States and regional distributions for
bituminous coal are presented in Charts 9 through 14. The
supporting data for these distributions are set out in
Schedule 26. In terms of absolute tonnages the Mid-Continent
region contains more than half of the total bituminous coal
reserve base. The remainder of the reserve base is located,
in order of importance, in the Northern Appalachian, Western,
Southern Appalachian, and Far West regions.
An examination of Charts 9 through 14 indicates a
substantial drop in reserves at the 1.43-1.75 pounds of SO-
per million Btu. In reality, this sharp decline in reserves
at this sulfur level probably does not exist, or is not as
severe as the distributions indicate. This exaggeration of
the decline in reserves at this interval occurred due to the
use of the average state heat contents for bituminous coals.
In the redistribution of the Bureau of Mines estimate a
substantial portion of the reserves that actually belong in
this category were shifted to the next higher or lower
interval.
For illustrative purposes and assuming the reserves
are evenly distributed within the intervals, the following
table sets out the quantities of reserves capable of
meeting a 1.2 pound per million Btu S0_ emission regulation.
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TABLE 4-5
ESTIMATED BITUMINOUS COAL RESERVE BASE CAPABLE OF
COMPLIANCE WITH NEW SOURCE STANDARD
(1.2 Pounds SO /MMBtu)
Region Million Tons Percent
Northern Appalachia^ 7,234.53 12.7
Southern Appalachia 3,581.25 22.3
Mid-Continent 310.06 0;3
Western 6,253.49 38.2
Far Western 897.51 62.8
Total United States 18,366.85 9.5
\_l Includes Southern West Virginia
Excluding the Mid-Continent region, a significant
portion of the reserves appears capable of compliance
with the aforementioned regulation. However, when the
Mid-Continent region is included, only 9.5 percent of the
total United States bituminous coal reserves can meet the
regulation. This illustrates the effect of the vast quantities
of high sulfur coal reserves found in this region.
As was noted in Table 4-2, approximately 39.5 billion
tons of bituminous coal were excluded from this SO-
distribution due to unknown sulfur contents of these
reserves.
4.3.3 Subbituminous Reserve Base
Distributions of the subbituminous coal reserve base for
the total United States and on a regional basis are presented
in Charts 15 through 17. The supporting data for these
distributions are set out in Schedules 27. The subbituminous
reserve base is limited to the Western and Far Western
regions, with more than 90 percent contained in the Western
region.
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For illustrative purposes, and assuming the reserves
are evenly distributed within the intervals, the reserves
capable of meeting a 1.2 pound SO- per MMBtu emission
regulation were calculated and set out in the table below.
Approximately 5.4 billion tons of subbituminous coal were
excluded from this estimate due to lack of sulfur contents,
TABLE 4-6
ESTIMATED SUBBITUMINOUS COAL RESERVE BASE CAPABLE OF
COMPLIANCE WITH NEW SOURCE STANDARDS
(1.2 Pounds S02/MMBtu)
Million Tons Percent
Region
Western 75,424.25 49.9
Far Western 6,291.41 53.2
Total United States 81,715.66 50.2
4.3.4 Lignite Reserve Base
Distribution of the lignite reserve base for the total
United States and on a regional basis are presented in
Charts 18 through 21. The supporting data for these
distributions are set out in Schedule 28. Although
lignite reserves occur in the Southern Appalachian region
(Alabama) analyses of these reserves are not available.
Hence, they were excluded from the distribution. The
majority of the lignite reserves are contained in the
Western region with minor reserves occurring in the Mid-
Continent region (Texas) and the Far Western region (Wash-
ington) . As in the case of Alabama, lignite reserves in
Arkansas and Alaska were excluded due to a lack of analyses,
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For illustrative purposes and assuming the reserves
are evenly distributed within the intervals, lignite
reserves capable of compliance with a 1.2 pound SO- per
MMBtu emission regulation were calculated and set out
in the following table.
TABLE 4-7
ESTIMATED LIGNITE RESERVE BASE CAPABLE OF COMPLIANCE
WITH NEW SOURCE STANDARD
(1.2 Pound S02/MMBtu)
Million Tons Percent
Region
Mid-Continent 29.80 1.1
Western 653.93 3.0
Far Western 0.00 0.0
Total United States 683.73 4.1
Although substantial reserves of lignite are reported
by the Bureau of Mines in sulfur ranges less than 0.7-0.8
percent by weight, only approximately 4 percent could
comply with a 1.2 pounds S02 .per MMBtu emissions regula-
tion due to the lower heat contents characteristic of
lignite.
4.4 Summary of Redistribution of the Reserve Base
by S02 Levels
Due to the quality of the data, resulting from the
redistribution of the Bureau of Mines estimates, and also
inherent difficulties of working with interval level data,
care should be exercised in any interpretation of the
estimates of coal which is capable of compliance with
a 1.2 pounds S0? per million Btu regulation. As was noted
-88-
-------
in each of the estimates of compliance, these figures
should be taken as indicative rather than a precise calcula-
tion. These estimates were based on the assumption that
the reserves are distributed evenly within each of the
sulfur level intervals. Therefore, all the reserves in
the £ 0.75, 0.76-1.08 pounds SO- per MMBtu categories, and
one-third of the reserves in the 1.09-1.42 category were
assumed capable of meeting a 1.20 pounds SO- per MMBtu
regulation. A slight change in the assumptions would yield
different results.
Perhaps the most important conclusion to be drawn
from this exercise is that there are inherent difficulties
in any attempt to manipulate these reserve estimate dis-
tributions. Even a slight change in assumptions can yield
significantly different and tentative results. As such, it
appears that any defensible statements or conclusions with
respect to the ability of coal reserves to comply with SO-
emissions regulations must come from a redistribution of the
individual coal analyses used in constructing the Bureau of
Mines distributions in 1C 8680 and 1C 8693.
If such a distribution were performed, estimates of
the mean and standard deviations for each of the SO-
intervals could enhance the quality of the final product
and facilitate interpretation.
A distribution of coal reserves on this basis would
be a more useful tool for policy purposes with respect
to determining clean fuel availability.
-89-
-------
APPENDIX
-------
APPENDIX A
Principles of the Mineral
Resource Classification System
of the U.S. Bureau of Mines
and U.S. Geological Survey
MINERAL RESOURCE CLASSIFICATION SYSTEMS OF THE
U.S. BUREAU OF MINES AND U.S. GEOLOGICAL SURVEY
GEOLOGICAL SURVEY BULLETIN 1450-A
A report published jointly by the
U.S. Bureau of Mines and
U.S. Geological Survey
Definitions of mineral resource classification
terms used by the U.S. Bureau of Mines and
U.S. Geological Survey
UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976
-------
UNITED STATES DEPARTMENT OF THE INTERIOR
THOMAS S. KLEPPE, Secretary
GEOLOGICAL SURVEY
V. E. McKclvey, Director
Library of Congress catalog-card No. 76-6000I15
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
Stock Number 024-001-02813-1
-------
FOREWORD
In order to use mineral resource terms with precision and com-
mon understanding and to compare resource data effectively, a
joint U.S. Bureau of Mines and U.S. Geological Survey work
group developed a standardized, definitive, broadly applicable
classification system to derive uniform, coordinated resource esti-
mates. This report presents the results of the work group that
developed the basic terms of mineral resource classification. Other
chapters in this series will present classification terms for specific
commodities.
Thomas V. Falkie V. E. McKelvey
Director, Bureau of Mines Director., Geological Survey
III
-------
CONTENTS
Page
Foreword III
General definition of mineral and energy resources Al
Philosophic basis for a resource classification 1
Glossary of resource terms 2
Areas of responsibility and operational .procedures 4
ILLUSTRATION
Page
FIGURE 1. Classification of mineral resources A2
-------
MINERAL RESOURCE CLASSIFICATION SYSTEMS OF THE
U.S. BUREAU OF MINES AND U.S. GEOLOGICAL SURVEY
PRINCIPLES OF THE MINERAL
RESOURCES CLASSIFICATION SYSTEM
OF THE U.S. BUREAU OF MINES
AND U.S. GEOLOGICAL SURVEY
GENERAL DEFINITION OF MINERAL AND ENERGY
RESOURCES . .
The dictionary definition of resource "something in reserve or
ready if needed" has been extended for mineral and energy re-
sources to comprise all materials surmised to exist having present
or future values. In geologic terms a mineral or energy resource is
a concentration of naturally occurring solid, liquid, or gaseous ma-
terials in or on the Earth's crust in such form that economic ex-
traction of a commodity is currently or_ potentially feasible. Ma-
terial classified as a reserve is that portion of an identified re-
source producible at a profit at the time of classification.
Total Resources are materials that have present or future value
and comprise identified or known materials plus those not yet
identified, but which on the basis of geologic evidence are pre-
sumed to exist. . .
PHILOSOPHIC BASIS FOR A RESOURCE CLASSIFICATION
Public attention usually is focused on current economic avail-
ability of mineral or energy materials (reserves). Long-term pub-
lic and commercial planning, however, must be based on the
probability of geologic identification of resources in as yet undis-
covered deposits and of technologic development of economic
extraction processes for presently unworkable deposits. Thus, all
the components of Total Resources must be continuously re-
assessed in the light of new geologic knowledge, of progress in
science, and of shifts in economic and political conditions.
Another requirement of longrterm planning is the weighing of
total or multi-commodity resource availability against a particular
need. To achieve this the general classification system must be
uniformly applicable to all commodities so that data for alternate
or substitute commodities can be compared.
Al
-------
A2
MINERAL RESOURCE CLASSIFICATION SYSTEMS
To serve these planning purposes Total Resoures are classified
both in- terms of economic feasibility and of the degree of geologic
assurance. The factors involved are incorporated in figure 1 to
provide a graphic classification of Total Resources.
General guides for the use of this classification system are as
follows:
1. Resource categories and definitions in the classification, as
specified in the glossary, should be applicable to all naturally oc-
curring concentrations of metals, nonmetals, and fossil fuels. The
categories may be subdivided for special purposes.
2. Definitions may be amplified, where necessary, to make them
more precise and conformable with accepted usage for particular
commodities or types of resource evaluations.
3. Quantities and qualities may be expressed in a variety of
terms and units to suit different purposes, but must be clearly
stated and defined.
GLOSSARY OF RESOURCE TERMS
Resource.—A concentration of naturally occurring solid, liquid,
or gaseous materials in or on the Earth's crust in such form
TOTAL RESOURCES
o
I
0
z
o
o
3
§
8
w
3
0)
•
5
5
£
c
5
1
IDENTIFIED
Demonstrated
Measured
R
Indicated
E S E R V E
RES
1_ _
r
Inferred
S
UNDISCOVEFIED
.. HYPOTHETICAL
(In known districts)
J
0 U R C E
+ J
n
i
SPECULATIVE
lln undiscovered
districts)
S
t
1
j
O
•
•
5
i
E
1
• Increasing d«
»sur»nc* -
FIGURE 1.—Classification of mineral resources.
-------
PRINCIPLES OF THE CLASSIFICATION SYSTEM A3
that economic extraction of a commodity is currently or
potentially feasible.
Identified resources.—Specific bodies of mineral-bearing material
whose location, quality, and quantity are known from geo-
logic evidence supported by engineering measurements with
respect to the demonstrated category.
Undiscovered resources.—Unspecified bodies of mineral-bearing
material surmised to exist on the basis of broad geologic
knowledge and theory.
Reserve.—That portion of the identified resource from which a
usable mineral and energy commodity can be economically
and legally extracted at the time of determination. The term
ore is used for reserves of some minerals.
The following definitions for measured, indicated, and inferred
are applicable to both the Reserve and Identified-Subeconomic
resource components.1
Measured.—Reserves or resources for which tonnage is computed
from dimensions revealed in outcrops, trenches, workings, and
drill holes and for which the grade is computed from the
results of detailed sampling. The sites for inspection, sam-
pling, and measurement are spaced so closely and the geologic
character is so well defined that size, shape, and mineral con-
tent are well established. The computed tonnage and grade
are judged to be accurate within limits which are stated, and
no such limit is judged to be different from the computed
tonnage or grade by more than 20 percent.
Indicated.—Reserves or resources for which tonnage and grade
are computed partly from specific measurements, samples, or
production data and partly from projection for a reasonable
distance on geologic evidence. The sites available for inspec-
tion, measurement, and sampling are too widely or otherwise
inappropriately spaced to permit the mineral bodies to be
outlined completely or the grade established throughout.
Demonstrated.—A collective term for the sum of measured and
indicated reserves or resources.
Inferred.—Reserves or resources for which quantitative estimates
are based largely on broad knowledge of the geologic charac-
1 The terms proved, probable, and possible (used by the industry and economic evalua-
tions of ore in specific deposits or districts) commonly have been used loosely and inter-
changeably with the terms measured, indicated, or inferred (used by the Department of the
Interior mainly for regional or national estimates). The terms "proved" and "measured"
are essentially synonymous. The terms "probable" and "possible," however, are not synony-
mous with "indicated" and "inferred." "Probable" and "possible" describe estimates of
partly sampled deposits—in some definitions, for example, "probable" is used to describe
deposits sampled on two or three sides, and "possible" for deposits sampled only on one
side; in the Bureau-Survey definitions, both would be described by the term "indicated."
-------
A4 MINERAL RESOURCE CLASSIFICATION SYSTEMS
ter of the deposit and for which there are few, if any, samples
or measurements. The estimates are based on an assumed
continuity or repetition, of which there is geologic evidence;
- this evidence may include comparison with deposits of similar
type. Bodies that are completely concealed may be included if
there is specific geologic evidence of their presence. Estimates
of inferred reserves or resources should include a statement
of the specific limits within which the inferred material may
lie.
Identified-Subeconomic.—Resources that are not Reserves, but
;. may become so as a result of changes in economic and legal
conditions.
Paramarginal.—The portion of Subeconomic Resources that (1)
borders on being economically producible or (2) is not com-
mercially available solely because of legal or political
circumstances.
Submarginal.—The portion of Subeconomic Resources which
. would require a substantially higher price (more than 1.5
times the price at the time of determination) or a major cost-
reducing advance in technology.
Hypothetical resources—Undiscovered resources that may rea-
sonably be expected to exist in a known mining district under
known geologic conditions. Exploration that confirms their
existence and reveals quantity and quality will permit their
reclassification as a Reserve or Identified-Subeconomic
resource.
Speculative resources.—Undisovered resources that may occur
either in known types of deposits in a favorable geologic
setting where no discoveries have been made, or in as yet
unknown types of deposits that remain to be recognized.
Exploration that confirms their existence and reveals quan-
tity and quality will permit their reclassification as Reserves
or Identified-Subeconomic resources.
AREAS OF RESPONSIBILITY AND OPERATIONAL
PROCEDURES
U.S. Bureau of Mines.—The Bureau appraises, analyzes, and pub-
lishes reserve estimates from base data supplied by the min-
eral and energy materials industry, the U.S. Geological
Survey, and other governmental agencies. The Bureau judges
commodity recoverability on existing economic and legal
factors.
-------
PRINCIPLES OF THE CLASSIFICATION SYSTEM A5
U.S. Geological Survey.—The Survey appraises, analyzes, and
publishes estimates of Total Resources. It reports such meas-
urable parameters of significance 'to resource evaluation as
location, quality, quantity, and situation of Identified
resources.
Annual Resource Summation.—The U.S. Bureau of Mines and
U.S. Geological Survey will confer and agree annually on
estimates in all of the resource categories defined above.
These data will be in Bureau or Survey publications and will
be available for inclusion in the Secretary's Annual Report
required by the Mining and Minerals Policy Act of 1970.
Ad Hoc Joint Conferences.—The Directors will convene ad hoc
joint work groups to resolve problems in the resource area.
-------
APPENDIX B
Goal Resource Classification System
of the U.S. Bureau of Mines and
U.S. Geological Survey
MINERAL RESOURCE CLASSIFICATION SYSTEMS OF THE
U.S. BUREAU OF MINES AND U.S. GEOLOGICAL SURVEY
GEOLOGICAL SURVEY BULLETIN 1450-B
A report published jointly by the
U.S. Bureau of Mines and
U.S. Geological Survey
Definitions of coal resource classification
terms used by the U.S. Bureau of Mines and
U.S. Geological Survey
UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976
-------
UNITED STATES DEPARTMENT OF THE INTERIOR
THOMAS S. KLEPPE, Secretary
GEOLOGICAL SURVEY
V. E. McKelvey, Director
Library of Congress catalog-card No. 76-600026
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
Stock Number 024-001-02814-0
-------
FOREWORD
In order to use mineral resource terms with precision and com-
mon understanding and to compare resource data effectively, a
joint U.S. Bureau of Mines and U.S. Geological Survey work
group developed a standardized, definitive, broadly applicable
classification system to derive uniform, coordinated resource esti-
mates. The principles of the system are given in Chapter A of this
series (Bulletin 1450-A). This chapter presents the classification
system for coal resources. Future chapters will present classifica-
tion terms for other specific commodities.
0 .
Thomas V. Falkie V. E. McKelvey
Director, Bureau of Mines Director, Geological Survey
III
-------
CONTENTS
'~ Page
Foreword III
Introduction Bl
Classification system ,. 1
Glossary of coal classification terms - 1
Criteria for coal resource/reserve identification 4
ILLUSTRATION
Page
FIGURE 1. Classification of coal resources B2
TABLE
Page
TABLE 1. Coal resource/reserve criteria B5
-------
MINERAL RESOURCE CLASSIFICATION SYSTEMS OF THE
U.S. BUREAU OF MINES AND U.S. GEOLOGICAL SURVEY
COAL RESOURCE CLASSIFICATION SYSTEM
OF THE U.S. BUREAU OF MINES AND
U.S. GEOLOGICAL SURVEY
INTRODUCTION
This method of classification is in conformity with the provi-
sions of the Joint Geological Survey-Bureau of Mines Resource
Classification Agreement of November 21, 1973, covering all min-
eral resources and will be used in future resource/reserve studies
on coal conducted by agencies of the Department of the Interior.
All resource and reserve estimates will be dated.
Within this system the term "coal resource" designates the esti-
mated quantity of coal in the ground in such form that economic
extraction is currently or potentially feasible. The "coal reserve"
is that part of the resource for which rank, quality, and quantity
have been reasonably determined and which is deemed to be min-
able at a profit under existing market conditions.
CLASSIFICATION SYSTEM
This system employs a concept by which coal beds are classified
in terms of their degree of geologic identification and economic
and technologic feasibility of recovery. In the following conceptual
diagram (fig. 1) showing the relationship of the various factors
involved, coal resources are located on the horizontal scale, in-
creasingly to the left, according to their degree of geological
assurance of existence, and on the vertical scale, increasingly up-
ward, according to their degree of economic arid technologic feasi-
bility of recovery.
The following general definitions of coal resource categories are
amplified by the criteria for resource identification, which follow
the Glossary. The criteria may be revised to reflect changing con-
ditions without affecting the definitions.
GLOSSARY OF COAL CLASSIFICATION TERMS
Resources.—Concentrations of coal in such forms that economic
extraction is currently or may become feasible.
Bl
-------
B2
MINERAL RESOURCE CLASSIFICATION SYSTEMS
COAL RESOURCES
As of January 1,
(billion short cons)
o
o
o
0
o
i
o
5
a
3
M
IDENTIFIED
Demo,
Measured
(*)
nitrated
Indicated
Inferred
UNDISCOVERED
HYPOTHETICAL
(In known districts)
SPECULATIVE
(In undiscovend
districts)
+
(j)
i i
t
o £
: i
b -i
•O £
: I
1
* -
-------
COAL RESOURCE CLASSIFICATION SYSTEM B3
Identified Subeconomic Resources.—The part of coal resources
that occurs in Demonstrated and Inferred Resources that is
not now minable economically.
Hypothetical Resources.—Undiscovered Coal Resources in beds
that may reasonably be expected to exist; in known mining
districts under known geologic conditions. In general, Hypo-
thetical Resources are in broad areas of coal fields where
points of observation are absent and evidence is from distant
outcrops, drill holes, or wells. Exploration that confirms their
existence and reveals quantity and quality will permit their
reclassification as a Reserve or Identified Subeconomic
Resource.
Speculative Resources.—Undiscovered coal in beds that may occur
either in known types of deposits in a favorable geologic set-
ting where no discoveries have been made, or in deposits that
remain to be recognized. Exploration that confirms their
existence and reveals quantity and quality will permit their
reclassification as Reserves or Identified Subeconomic
Resources.
The following definitions are applicable to both the Reserve and
Identified Subeconomic Resource components.
Measured.—Coal for which estimates of the rank, quality, and
quantity have been computed, within a margin of error of less
than 20 percent, from sample analyses and measurements
from closely spaced and geologically well-known sample sites.
Indicated.—Coal for which estimates of the rank, quality, and
quantity have been computed partly from sample analyses
and measurements and partly from reasonable geologic pro-
jections.
Demonstrated.—A collective term for the sum of coal in both
Measured and Indicated Resources and Reserves.
Inferred.—Coal in unexplored extensions of Demonstrated Re-
sources for which estimates of the quality and size are based
on geologic evidence and projection.
Rank.—The classification of coals relative to other coals, according
to their degree of metamorphism, or progressive alteration,
in the natural series from lignite to anthracite (Classification
of Coal by Rank, 1938, American Society for Testing Materi-
als, ASTM Designation D-388-38, p. 77-84).
Quality or Grade.—Refers to individual measurements such as
heat value, fixed carbon, moisture, ash, sulfur, phosphorus,
major, minor, and trace elements, coking properties, petro-
logic properties, and particular organic constituents. The indi-
-------
B4 MINERAL RESOURCE CLASSIFICATION SYSTEMS
vidual quality elements may be aggregated in various ways
to classify coal for such special purposes as metallurgical,
gas, petrochemical, and blending usages.
CRITERIA FOR COAL RESOURCE/RESERVE
IDENTIFICATION
Estimates of the different classes of coal resources and reserves
are arbitrarily based upon three criteria: (1) thickness, rank, and
quality of the coal bed, (2) depth of the coal bed, and (3) the
proximity of the coal resource data upon which the estimate was
based. Depth and thickness are criteria because they control eco-
nomic and technologic feasibility of recovery. The criteria far each
class are described below and summarized in table 1 and will be
used in preparing all Department of the Interior coal resource/
reserve estimates from January 1, 1975, until further revised.
These criteria apply only to those coal bodies that are or will be
economically extractable by underground, surface, and/or in situ
methods. Coal thinner than 14 inches (35 cm) "(anthracite and
bituminous) and 30 inches (75 cm) (subbituminous and lignite)
and all coal deeper than 6,000 feet (1,800 m) is excluded. These
thinner and deeper coals will be considered at a later date. Coal
containing more than 33 percent ash is excluded from resource
and reserve estimates.
Identified Resources.—Include beds of bituminous coal and an-
thracite 14 inches (35 cm) or more thick and beds of sub-
bituminous coal and lignite 30 inches (75 cm) or more thick
that occur at depths to 6,000 feet (1,800 m), and whose exist-
ence and quantity have been delineated within specified de-
grees of geologic assurance as measured, indicated, or infer-
red. Include also thinner and/or deeper beds that presently
are being mined or for which there is evidence that they could
be mined commercially.
Undiscovered Resources.—Include beds of bituminous coal and
anthracite 14 inches (35 cm) or more thick and beds of sub-
bituminous coal and lignite 30 inches (75 cm) or more thick
that are presumed to occur in unmapped and unexplored
areas to depths of 6,000 feet (1,800 m).
Remaining Resources.—Includes the sum of the Identified and
Undiscovered Resources as of the date of the estimate.
Cumulative Production.—Includes the sum of all production prior
to the date of the estimate.
-------
COAL RESOURCE CLASSIFICATION SYSTEM B5
TABLE 1.—Coal resource/reserve criteria
_ .. _ . ... % Thickness, Inches
Depth. Feet (Metres) (Centimetres)
Total Resources and
Undiscovered Re-
sources.
Anthracite and ^6,000 (1,800) 5=14 (35)
bituminous
coal.
Subbituminous =£6,000 (1,800) 5=30 (75)
coal and
lignite.
Identified Resources.1
Anthracite and ^6,000 (1,800) 5=14 (35)
bituminous
coal.
Subbituminous =£6,000 (1,800) ==s30 (75)
coal and
lignite.
•
Reserve Base.'
Anthracite and ^1,000 (300) 5*28 (70)
bituminous
coal
Subbituminoua ^1,000 (300) 5±60 (150)
coal.
Lignite ^120 (40) 5=60 (150)
Reserves.
Criteria same as Reserve Base but with Recovery Factor applied.
Subeconomic Resources}
Anthracite and 0-1,000 (300) 14 (35)-28 (70)
bituminous 1,000 (300)-6,000 (1,800) 5=14 (35)
coal.
Subbituminous 0-1,000 (300) 30 (75)-60 (150)
coal 1.000 (300)-6,000 (1,800) 5=30 (75)
Lignite 0-120 (40) 30 (75)-60 (150)
120 (40)-6,000 (1,800) 5=30 (75)
'Identified Resources are classified as Measured. Indicated, and Inferred according to the
degree of geologic assurance as described in the text.
-The Reserve Base includes some beds that are thinner and/or deeper than the general
criteria permit, but that presently are being mined or are judged to "be minable com-
mercially at this time.
•Also includes currently nonrecoverable part of Reserve Base.
Total Original Resources.—Includes the sum of the Remaining
Resources and Cumulative Production as of the date of the
estimate.
Reserve Base.—Includes beds of bituminous coal and anthracite
28 inches (70 cm) or more thick and beds of Subbituminous.
coal 60 inches (150 cm) or more thick that occur at depths to
1,000 feet (300 m). Includes also thinner and/or deeper beds
that presently are being mined or for which there is evidence
that they could be mined commercially at this time. Includes
-------
B6 " MINERAL RESOURCE CLASSIFICATION SYSTEMS
beds of lignite 60 inches (150 cm) or more thick which can be
surface mined—generally, those that occur at depths no
greater than 120 feet (40 m).
Reserve.—Includes that portion of the Reserve Base that can be
mined at the time of classification (See Recovery Factor).
Recovery Factor.—On a national basis the estimated Recovery
Factor for the total Reserve Base is 50 percent. More precise
recovery factors can be computed by determining the total
' coal in place and the total coal recoverable in any specific
locale.
Subeconomic Resources.—Include all Identified Resources that do
not fall into the Reserve category. Include in this category
beds of bituminous coal and anthracite 14 inches (35 cm) to
28 inches (70 cm) thick and beds of subbituminous coal 30
inches (75 cm) to 60 inches (150 cm) thick that occur at
depths to 1,000 feet (300 m). Include also beds of bituminous
coal and anthracite 14 inches (35 cm) or more thick and beds
of subbituminous coal 30 inches (75 cm) or more thick that
occur at depths between 1,000 (300 m) and 6,000 feet (1,800
m). Include lignite beds 30 inches (75 cm) or more thick that
cannot be surface mined—generally those that occur at
depths greater than 120 feet (40 m), and lignite beds 30
inches (75 cm) to 60 inches (150 cm) thick that can be sur-
face mined. Include the currently non recover able portion of
the Reserve Base.
The following criteria are applicable to both the Reserve and
Subeconomic Resources components:
Measured.—Resources are computed from dimensions revealed in
outcrops, trenches, mine workings, and drill holes. The points
of observation and measurement are so closely spaced and the
thickness and extent of coals are so well defined that the ton-
nage is judged to be accurate within 20 percent of true ton-
nage. Although the spacing of the points of observation neces-
sary to demonstrate continuity of the coal differs from region
to region according to the character of .the coal beds, the
points of observation are no greater than \'<> mile (0.8 km)
apart. Measured coal is projected to extend as a 1/4-mile (0.4-
km) wide belt from the outcrop or points of observation or
measurement.
Indicated.—Resources are computed partly from specified meas-
urements and partly from projection of visible data for a
reasonable distance on the basis of geologic evidence. The
-------
COAL RESOURCE CLASSIFICATION SYSTEM B7
points of observation are !X> (0.8 km) to l'/2 miles (2.4 km)
apart. Indicated coal is projected to extend as a V->-mile (0.8-
km) wide belt that lies more than 14 mile (0.4 km) from the
outcrop or points of observation or measurement.
Inferred.—Quantitative estimates are based largely on broad
knowledge of the geologic character of the bed or region and
where few measurements of bed thickness are available. The
estimates are based primarily on an assumed continuation
from Demonstrated coal for which there is geologic evidence.
The points of observation are V/-> (2.4 km) to 6 miles (9.6
km) apart. Inferred coal is projected to extend as a 2^4-mile
(3.6-km)widebelt that lies more than % mile (1.2 km) from
the outcrop or points of observation or measurement.
Hypothetical Resources.—Quantitative estimates are based on a
broad knowledge of the geologic character of a coal bed or
region. Measurements of coal thickness are more than 6 miles
(9.6 km) apart. The assumption of continuity of a coal bed
is supported only by geologic evidence.
Speculative Resources.—Quantitative estimates are based on geo-
logic assumptions that undiscovered coal may occur in known
types of deposits or in favorable geologic settings.
-------
APPENDIX C
Bureau of Mines Analyses of Tipple
and Delivered Samples of Coal
The distribution of the reserve base by sulfur content
reported in 1C 8680-93 relies primarily on the coal analyses
collected by the Bureau of Mines in connection with the pur-
chase of coal for various Government agencies. Since the
majority of coal reserve studies by sulfur content rely
either indirectly, through the acceptance of the sulfur
distributions in 1C 8312 and 1C 8680-93, or directly on
these analyses they are probably the one most important
source of coal sulfur data.
The purpose of these analyses collected by the Bureau
of Mines is to determine whether coal suppliers are providing
coal of the specifications as defined in coal purchase con-
tracts. These samples are analyzed by the Bureau of Mines
and if the coal is not of the quality guaranteed by the con-
tractor, price adjustments are made.
Samples for these analyses may be collected at two
different points in coal shipments. First, tipple samples
are collected after the coal has received final treatment
at the tipple or cleaning plant, or is loaded into railroad
cars or trucks. As an alternative, samples may be collected
from delivered coal during unloading. Both types of samples
are analyzed at the Bureau of Mines laboratory. All samples
are collected in accordance with instructions issued by
the Bureau of Mines.—
These analyses are published as Bureau of Mines Report
of Investigations (RI) and the publications in this series—'
I/ Snyder, N.H. (rev. by S.J. Aresco) Coal Sampling (Revision
of Technical Paper 133). BuMines Handbook, 1957.
2/ Aresco, S.J., Analyses of Tipple and Delivered Samples
of Coal (Collected during Fiscal Year ), BuMines RI
-------
reflect samples collected from 1948 to present. Similar
publications report samples collected prior to 1948.
The analyses in these publications are arranged alpha-
betically with respect to states, counties, towns, and mines,
and are listed as follows:
1. Proximate analysis — moisture, volatile matter,
fixed carbon, and ash.
2. Ultimate analysis — ash, sulfur, hydrogen, carbon,
nitrogen, and oxygen.
3. Calorific value — the heat of combustion of a
substance, expressed in British thermal units
(Btu) per pound.
4. Softening temperature of ash, when such determina-
tions were made.
5. Free-swelling index, when such tests were made.
6. Hardgrove grindability index, when such tests
were made.
7. Number of deliveries.
The analyses are given to the nearest 0.1 percent and
the British thermal units to the nearest 10, although the
laboratory determinations are recorded to the 0.01 percent
and nearest British thermal unit. Individual analyses are
also identified as tipple or delivered samples and by the
extent of coal preparation (washed or partially washed).
The use of these analyses to distribute coal reserves
by sulfur content in various reports raises several questions,
Perhaps the most important questions are:
1) To what extent do these samples approximate the
physical characteristics of coal in current production?
-2-
-------
2) To what extent do these samples reflect the
physical characteristics of reserves and resources
in the ground?
In an attempt to gain some insight to these problems,
a comparison of the Bureau of Mines analyses for two years,
1966 and 1975, was performed. Since these publications do
not report totals or averages of these analyses by geographic
location or otherwise, a comparison on a larger scale would
be a formidable task beyond the scope of this study. For
this reason the emphasis of this exercise is limited to the
State of West Virginia. Table C-l sets out the salient
features of this comparison.— In 1966 these analyses
included 7,211 coal samples from 21 states, while in 1975
the number of states represented by 2,200 samples was 14.
In terms of tonnages the samples in 1966 were representative
of 5.5 million tons of coal purchased by the Government. By
1975 these purchases diminished to approximately 3 million
tons. These samples represent all ranks of coal from lignite
to anthracite. Compared to total production of all ranks of
coal, Government purchases represented approximately 1.0
percent and 0.5 percent in 1966 and 1975, respectively.
A comparable analysis for West Virginia indicates
Government purchases in 1966 and 1975 accounted for only 0.6
and 0.3 percent of production in these respective years. A
more in-depth analysis shows that these purchases were
primarily low-sulfur, high Btu coal. Additionally, in both
years, more than 80 percent of the purchases represented
prepared coal.
These analyses are reported on an "as received" and "dry"
basis. "As received" does not imply raw coal, but rather
means as received at the testing laboratory. Coal reported
I/ Tables are located at the end of Appendix C.
-3-
-------
on an "as received" basis could be either raw coal or coal
that has been cleaned or prepared. Coal reported on a dry
basis reflects the physical characteristics of the coal when
all moisture is removed. Since 1C 8680-93 reports sulfur
contents, by percent, on a dry basis the sulfur content of
the reserve base is slightly overstated. This is because
as the moisture is removed from the coal the sulfur content
as a percent of total sample weight will increase. In the
case of West Virginia, this fact would be of no great con-
sequence since the average moisture content of the coal is
only about 3 percent. However, in the western coal fields
of Montana and Wyoming where moisture contents can average
15-16 percent by weight, this factor would be more significant.
A coal containing 15 percent moisture and 0.7 percent sulfur
on a dry basis would actually be 0.6 percent sulfur coal in
its raw state.—
Another area of concern with respect to these analyses
is the rather high average heat content reported for West
Virginia coal. As shown in Table C-l the average heat con-
tent of Government purchased coal was reported as 13,735
Btu/pound and 13,332 Btu/pound "as received" in 1966 and
1972, respectively. The average analyses of coal reported by
the Bureau of Mines in 1C 8680-93 show the average heat content of
West Virginia coal to be 13,540 Btu/pound "as received."
This corresponds closely with the analyses of Government
purchases as it should since they were the primary source of
T/This problem can essentially be eliminated by converting
the reserves, by sulfur content, in 1C 8680-93 to a
pounds of SO- per million Btu basis using the reported
sulfur contents (dry basis) and the average heat contents
(dry basis). When the redistributions contained in
Section 4 of this report were performed, this adjustment
was not recognized. To this extent, the reported redis-
tributions in terms of SO- emissions are overstated.
-4-
-------
analysis. Therefore, it appears the analyses in 1C 8680-93
and other studies which rely on Bureau of Mines data do not
represent only raw coal, as in the reserve base, but also
include cleaned coal. The comparison set out in Table C-l
indicates these analyses are predominantly (more than 80
percent) those of prepared (washed) coal samples.
An examination of coal deliveries to electric utilities
in West Virginia during the nine year period from 1966 to
1974 is set out in Table C-2. Presumably, the majority of
this coal was produced in West Virginia. These deliveries
give some indication of the type of coal burned by electric
utilities, the major consumers of West Virginia's coal. As
shown in Table C-2 the weighted average heat content of
coal delivered to West Virginia electric utilities during
these nine years was 11,704 Btu/pouncl. Based on the hypothesis
that coal burned by West Virginia utilities was a lower
quality coal and the premium coal was purchased by utilities
in other states, recent deliveries to utilities were examined.
Table C-3 represents all deliveries of West Virginia coal
as reported to the Federal Power Commission during January 1976.
It appears that West Virginia utilities do burn coal with a
lower heat content, but the difference is not large. An
important point to note on Table C-3 is the average heat con-
tent of West Virginia coal deliveries to all United States
utilities. This figure of 11,950 Btu/pound differs significantly
from the 13,540 Btu/pound reported in. 1C 8680-93.
The implication of this analysis is that if the average
heat content of West Virginia coal is indeed 13,540 Btu/pound,
then large quantities of 14,000-15,000 Btu/pound coal should
remain in the States' reserves. Coal with heat contents in
this range are not presently being produced, and in actuality
probably do not exist in significant quantities. A more
reasonable explanation is that the average heat content of
West Virginia coal is in reality, about 12,000 Btu/pound and
-5-
-------
the 13,540 Btu/pound figure reported in 1C 8680-93 is biased
upward due to Government purchases of premium quality coals.
Therefore, unless the Bureau of Mines analyses were (1)
adjusted to reflect the physical characteristics of raw coal
prior to preparation, or (2) based on raw coal analyses
only, the resulting distribution of the reserves using these
analyses would be biased.
The Bureau of Mines does in fact state that the distribu-
tion of reserves in 1C 8680-93 was based on raw coal samples
only. Of the 26,468 West Virginia coal analyses in the
Bureau of Mines data base 21,499 or approximately 81 percent
were used in the distribution of reserves by sulfur content.
If these 21,499 samples do in fact represent raw coal, it
appears the data base contains a preponderance of coal
samples collected many years ago. This is based on the
comparison of the 1966 and 1975 analyses. As mentioned
previously, less than 20 percent of these analyses were
based on raw coal.
In order to determine how well Government purchases
represent the reserve base of West Virginia, Table C-4 was
constructed. Column (1) in this table are the bed numbers,
as reported in 1C 8680-93, from which the sample analyses
of Government purchases were collected during 1966. Column
(2) is the bed name and Column (3) is the estimated reserve
base for each of these beds as reported in 1C 8680-93. As
shown in Table C-4, these beds represent approximately 66
percent of West Virginia's total reserve base. It should be
noted that this is a comparison for 1966 only. Analyses
collected during other years will most likely include ad-
ditional beds, thereby raising this percentage.
These analyses will represent the reserve base only
to the extent that the physical characteristics of the reserve
base are the same as the coal previously produced from these
beds from which the samples were collected.
-6-
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With respect to the two questions posed at the beginning
of this exercise, they can now be at least partially answered.
First, it appears that the Bureau of Mines analyses do not
adequately represent the physical characteristics of current
coal production to the extent that:
1) Government coal purchases account for only a
small portion of United States coal production.
2) Coal analyses reported by electric utilities
differ significantly from the Bureau of Mines analyses.
3) Government coal purchases are extremely biased
in favor of premium quality coals.
This analysis was performed for West Virginia only and
some of the problems illustrated may be unique in this state
due to the variations in the physical characteristics of
this coal. In other states, the problems indicated may be
greater or smaller depending on the variability inherent in
the reserve base.
It is difficult to determine the validity of any
of the reserve studies by sulfur content without a complete
knowledge of the analyses used in the distribution of reserves.
Although this analysis focused primarily on 1C 8680-93, it
applies to the several other studies as well, most of which
were based on the same analyses. The Bureau of Mines does
present a tabulation of the analyses used in 1C 8680-93
but these analyses are misleading to the extent they do not
represent the reserve base or raw coal but rather both raw
and prepared coal. Since this publication is an attempt to
quantitatively measure the reserve base, a more useful and
appropriate tabulation would list only the physical character-
istics of the analyses corresponding to raw coal samples.
-7-
-------
TABLE C-l
COMPARISON OF COAL ANALYSES COLLECTED BY
BUREAU OF MINES 1966 AND 1975
Total United States
Number of States Represented
Number of Samples
Government Purchases (million tons)
Total U.S. Coal Production (million tons)
Government Purchases as % of Total
Production
1966
-21
7211
5.5
546.0
1.0
. 1975.
14
2200
3.0
646.1
0.5
West Virginia
Number of Samples
Government Purchases (million tons)
Total West Virginia Production (million
tons)
Government Purchases as % of W. Va.
Production
Wtd. Average Sulfur Content (Dry) of
Government Purchases (%)
Wtd. Average Heat Content of
Government Purchases (Btu/pound A.R.)
Government Purchases of Washed Coal
as % ;of Total W.Va. Purchases
1966
1554
0.9
1975
382
0.3
149.2
0.6
1.04
109.2
0.3
1.09
13,735 13,332
80.8 83.1
Source: Bureau of Mines, Analyses of Tipple and Delivered Samples
of Coal Collected During 1966 and 1975.
-8-
FA-020539
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TABLE C-2
AVERAGE HEAT CONTENT OF COAL DELIVERIES TO
WEST VIRGINIA ELECTRIC UTILITIES, 1966-1974 I/
Year
1974
1973
1972
1971
1970
1969
1968
1967
1966
Weighted
Deliveries
(000 tons)
. 25,591
22,776
19,659
16,361
14,957
14,554
13,022
11,199
10,789
Average 1966-1974
_!/ Source: National Coal Association,
Average Heat Content
(Btu/pound)
11,485
11,762
11,734
11,529
11,659
11,887
11,889
11,764
11,848
11,704
St€:am-Electric Plant Factors,
1967-1975.
TABLE C-3
DELIVERIES OF WEST VIRGINIA COAL TO ELECTRIC UTILITIES
JANUARY 1976 I/
Utility
Location
West Virginia
Other States
Total U.S.
Number of
Deliveries
104
140
244
Tons Delivered
(Thousands)
1,701.27
1,424.25
3,125.52
Average Heat Content
(Btu/pound) (as received)
11,815
12,111
11,950
I/ Federal Power Commission, FPC Form 423, January 1976.
-9-
FA-020540
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TABLE C-4
COMPARISON OF GOVERNMENT COAL PURCHASE SAMPLES
.TO RESERVE BASE, BY WEST VIRGINIA COAL BED.
Bed
Number
Bed
Name
(1)
29
33
36
71
80
84
111
121
135
136
151
157
167
168
170
176
177
179
216
252
318
334
342
344
(2)
Sewickley
Redstone
Pittsburgh
Upper Freeport
Middle Kittaning
No. 5 Block
Coalburg
Dorothy.
Chilton
Lower Chilton
Upper Cedar Grove )
Cedar Grove )
Alma
Peerless
No. 2 Gas
Powellton
Eagle )
Big Eagle ).
Bens. Creek
Little Eagle
Gilbert
Douglas
Fire Creek
Pocahontas #6
Pocahontas #4
Pocahontas #3
Total
Reserve Base
1C 8680-93
(Million tons)
(3)
3017.44
448.27
5267.34
1071.45
313.31
2286.84
1349.76
969.43
775.82
29.35
1777.04
1597.97
454.23
2516.62
206.32
1165.12
54.89
160.50
167.75
70.95
459.42
298.38
394.35
1272.57
26,125.12
Reserve Base Represented By 1966
Bureau of Mines Analysis
Total Reserve Base
26125.12
39589.79
= 66.0%
-10-
FA-020541
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APPENDIX D
National Petroleum Council, U.S. Energy Outlook,
Coal Availability/ 1973. Prepared for the National
Petroleum Council by the Coal Task Group of the
Other Energy Resources Subcommittee of the National
Petroleum Council's Committee on U.S. Energy Outlook
This report is a part of a comprehensive study of the
Nation's energy outlook requested by the Assistant Secretary —
Mineral Resources, Department of the Interior. The objective
of the report is to project the energy outlook in the Western
Hemisphere into the future as near to the end of the century
as is feasible. With respect to coal reserves, the report
attempts to determine the adequacy of coal reserves in meeting
demand during the next 15 years and through the rest of the
century.
The Coal Task Group reserve estimates were based on a
Bureau of Mines study that reported United States coal resources
of all ranks in beds over 28 inches thick and under less than
1,000 feet of overburden.— These measured and indicated
resources as of January 1, 1970 were as follows:
Millions of
Short Tons
Bituminous coal 261,510
Subbituminous coal and lignite 119,861
Anthracite 12,735
Total 394,106
These 394 billion tons consisted of 349 billion tons
of underground resources and 45 billion tons of surface
resources. In the case of underground coal, the 349 billion
tons were further narrowed down to "economically available
I/ These resources are equivalent to the reserve base,
-------
reserves" by excluding underground lignite and intermediate
thickness bituminous and subbituminous seams. Intermediate
thickness seams are defined as 28 to 42 inches for. bituminous
and 5 to 10 feet for subbituminous. A recovery factor of 50
percent was then used to arrive at the total recoverable under-
ground reserves. This reduces the total underground reserves
to 104.7 billion tons. A summary of the procedure is as
follows:
SUMMARY OF UNDERGROUND COAL
ESTIMATE METHODOLOGY
Billion Tons
Remaining measured and indicated
reserves 349.1
Minus: underground lignite and
intermediate thickness bituminous
and subbituminous seams 139.9
Equals: economically available
reserves 209.2
Minus: 50 percent recovery factor 104.6
Equals: recoverable reserves 104.6
For surface mining the Coal Task Group reported that the
remaining recoverable reserves were 45.0 billion tons. This
figure is the same as the Bureau of Mines report of 45.0 billion
tons of remaining measured and indicated reserves. The Coal
Task Group did not apply a recovery factor for surface reserves
"since in most cases of surface mining, it will exceed 90
percent."
Coal reserves were categorized by regions. These regions
were selected to group the reserves estimates so that each
region is somewhat uniform in terms of coal deposits and mining
method. The composition of these regions is set out in Table
-2-
-------
1. It should be noted that the underground and surface
reserves are independently assigned to these regions. As
an example, although the underground reserves of Kentucky
are assigned to Region 4, the surface reserves are assigned
to Region 1.
Tables 2 and 3 contain the estimated reserves on a
regional and national basis. Also included are estimates of
the life of these recoverable reserves based on the 1970
rate of production and for compounded annual growth rates
of 0, 3 and 5 percent. Since this study was concerned with
the adequacy of coal reserves through the rest of the century,
it was concluded that "these reserves are of sufficient mag-
nitude to obviate production from any thinner or deeper
seams for some time to come."
The Coal Task Force noted that these reserves estimates,
those in Table 2 in particular, are sensitive to the impact
of mining technology. Since this tabulation assumes the
application of current mining technology and economics and
a 50 percent recoverability factor, a wide scale switch to
longwall mining or other system which yields higher recovery
could add substantially to the recoverable reserves.
-3-
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TAEl E 1
COAL FIELDS OF THE UNITED STATES
Underground
t>
Surface
Region 1
1.
2.
1.
2.
3.
1.
2.
3.
1.
2.
3.
1.
2.
1.
West Virginia
Pennsylvania
Mercer County, W.
McDowell County,
Wyoming County,
Illinois
Indiana
Ohio
Kentucky
Tennessee
Virginia
Utah
Colorado
Alabama
1.
2.
3.
. 4.
Region 2
Va. 1.
W. Va. 2.
W. Va. 3.
4.
Region 3
1.
Region 4
1.
2.
3.
4.
Region 5
• 1.
2.
..3.
Region 6
Kentucky
West Virginia
Virginia
Tennessee
•*
Illinois
Indiana
Iowa
Ohio
Pennsylvania
Colorado.
Montana
New Mexico
Wyoming
Oklahoma
Kansas •
Missouri
1. North Dakota
* Does not include Mercer, McDowell and Wyoming Counties in West Virginia; these three
counties produce mainly low-volatile coking coal and are considered separately in Region 2.
Source: National Petroleum Council, U.S. Energy Outlook, Coal Availability,
1973, p. 19. '
-------
TABLE 2
UNDERGROUND COAL RESERVES AND PRODUCTION
(Min.iblc by Underground Mining Methods)
Billions of Tons
Region
1
2
3
4
5
6
Other
Total §
.Remaining
Measured and Economically
Indicated Available
Reserves* Reserves!
92.7
9.1
83.1
34.5
21.9
1.6
106.3
349.1
* Bilummous, subbituminous and
(sec Figure 50).
t Excludes
1 Based on
§ May not
67.1
9.1
59.5
24.4
13.3
.6 .
35.2
Recoverable
Reserves^
' 33.5
4:6
29.7
12.2
• • 6.7
.3
17.6
209.2 104.6
lignite in seams of "intermediate"
lignite and "intermediate" thickness
50-percent recovery ol
add correctly due to ro
economically
mding.
seams of bituminous
available reserves.
1970
Production
(Millions of
Tons)
145.8
N.A.
52.3
95.0
8.6
9.1
N.A.
338.8
Or greater thickness
find subbituminous
Life of-Recoverable Reserves
at % CS'rpwth Rate (Years)
0%
230
—
568
129'
774
35
- .
309
and less than
coal.
' . . 3%
69
—
96
52
106
23
-
80
1,000 (eet
5%
50
—
68
40
74 .
• 20
-.
58
overburden
•
TABLE 3 .
SURFACE COAL RESERVES AND PRODUCTION
Region
1
2
3
4
5
6
Other
Total
(Minable
Recoverable
Reserves
(Billions of Tons)
4.2
. 5.6
0.8
23.8
1.6
2.1
.6.9
45.0
by Surface Mining Methods)
1970
Production
(Millions of Tons)
101.2
91.0
25.1 '
19.1
8.3 •
5.6
13.8
264.1
at
0%
42
62
32
1.246
193
375
500
170
Life of Reserves
% Growth Rate (Years)
3%
27 ~
36
23 .
122
65
85
95
61
5%
23
29
19
85
48
62
67
46
Source: National Petrol-cum Council, U.S. Energy Outlook, Coal Availability-,
1973, p. .22.
-------
APPENDIX E
REVIEW AND COMMENTS RECEIVED FROM
U.S. BUREAU OF MINES
-------
IN REPLY REFER TO:
United States Department of the Interior
BUREAU OF MINES
2401 E STREET, NW.
WASHINGTON, B.C. 20241
EBM:MMS/DA-F-DC
December 14, 1976
Mr. Wayne G. Mikutowicz
Foster Associates, Inc.
1101 Seventeenth Street, NW.
Washington, D.C. 20036
Dear Mr. Mikutowicz:
This is in reference to your letter of November 30 requesting our review
of the report, "An Assessment of the Discrepancies in United States Low
Sulfur Coal Reserve Estimates," by Foster Associates, Inc.
To our knowledge, the report encompasses all of the major efforts to
delineate coal resources and reserves by sulfur content. In general,
the treatment of the subject is adequate. We do not concur, however,
with the author's assumptions that bias may have been introduced in the
sulfur distribution of reserves in Bureau of Mines reports on the
reserve base because of the use of analytical data on coals that had
been sized and cleaned.
We must emphasize that the distribution of coal reserves by sulfur content
in all Bureau of Mines reports on the U.S. coal reserve base (Information
Circulars 8655, 8678, 8680, and 8693) was based entirely upon raw coal
analytical data. Although this was not stated specifically in the reports
on the western States, only raw coal analytical data were used for both
the east and the west.
With respect to Section 4.0 (A Restatement of U.S. Bureau of Mines
Reserve Base Estimates in Terms of Potential S02 Emissions), the report
states that the authors are "unaware of any attempt by the Bureau of Mines
to compute such distribution of reserves by S0£ emissions." This state-
ment is essentially correct but we must call your attention to a recently
published Bureau of Mines report, "Effects of Air Quality Requirements
on Coal Supply," which attempts to show reserves of compliance coal in
the various States and AQCR's. This study was preceeded by another,
"Assessment of the Impact of Air Quality Requirements on Coal in 1975,
1977, and 1980," published in 1974.
^OUJT/O*
-------
The report appears to serve the purpose for which it is intended - to
point out variances - we prefer this term to discrepancies - in the
reserve estimates. We feel, however, that the report should state more
emphatically that differences in the reports were due mainly to
different interpretations of the available data, which are shallow in
many respects for some States and coalbeds.
Specific comments on various sections of the report are given in the
attachment to this letter.
Sincerely yours,
^t £ /Woo&-£ot
Zane E. Murphy
Chief, Division of Coal
Enclosure
-------
Review of Draft Report, "An Assessment pf the Discrepancies in United
States Low Sulfur Coal Reserve Estimates," by Foster Associates, Inc.
1. Page 30, Par. 1 - It should be pointed out that the primary
assumption for Illinois and Indiana was used first. Then,
in a separate section, the manual distribution was made to
reflect personal judgment factors of personnel of the Illinois
and Indiana Geology Surveys.
2. Pages 61, 62, 64 - Sample analysis data were used in Appendix "C"
of IC's 8680-93. It was not determined that these estimates were
inaccurate but Illinois and Indiana Geologic Survey judgments
were incorporated into Appendix "D" to show a difference in
opinions. If all other State Geologic Surveys had been asked
for opinions, it probably would have resulted in changes for
every State.
3. Page 62 - In order to validate the historical data's application,
it would be necessary to drill and core all coal deposits in the
U.S. If this type of data were available, it would not have been
necessary to use historical data.
4. Page 62, Par. 3 - Distribution of the reserve base was made solely
from samples that had not been mechanically cleaned or even
partially cleaned.
5. Page 63, Par. 3 - The same probability distribution was used
for both 1C 8680 and 1C 8693.
6. Page 64, Par. 3 - We feel the procedure did work for Illinois
and Indiana as well as for other States. The two sets of data
for Illinois and Indiana were based upon different judgments.
7. Page 65, Par. 2 - There is no discrepancy in the data base. We
reiterate - raw coal samples only were used. This is stated
specifically on page 430 of 1C 8680.
8. Pages 64, 65 - The procedure used to allocate the reserve base
estimates by sulfur content was the same for all Bureau of Mines
IC's on demonstrated coal reserve base.
9. Pages 65, 66 - The procedure used for allocation of the reserve
base of the western States is given on page 11 of 1C 8678.
10. Page 72, Par 2 - BOM has written and tested a computer program that
will display reserve base tonnages by either pounds of S02 per
million Btu or pounds of elemental sulfur per million Btu. Publi-
cation of this information is awaiting an update of the reserve
base to January 1, 1976.
-------
-2-
11. Appendix C, Page 5, Par. 1 - Again, the analytical data in
IC's 8680-93 do not include cleaned coal analyses.
12. Appendix C, Page 6, Par. 2 - In addition to the +26,000 analyses
of raw West Virginia coal samples, BOM has an estimated 28,000
sample analyses of mechanically cleaned West Virginia coals in
the coal data bank.
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