U.S. Coal Resources and Reserves Assessment

Science Center Objects

The U.S. Coal Resources and Reserves Assessment Project, as part of the U.S. Geological Survey (USGS) Energy Resources Program, conducts systematic, geology-based, regional assessments of significant coal beds in major coal basins in the United States. These assessments detail the quantity, quality, location, and economic potential of the Nation’s remaining coal resources and reserves and provide objective scientific information that assists in the formulation of energy strategies, environmental policies, land-use management practices, and economic projections.

To read details regarding this project, see FS-2017-3067

Overview

The coal industry in the United States has undergone fundamental changes over the past several years that have resulted in a reduction in the number of operating coal mines, the merging or consolidation of numerous coal companies, and a drastic decrease in coal production. Since 2008, when a record of more than 1.17 billion short tons of coal were produced in the U.S., annual coal production volumes have dropped precipitously. In 2018, nearly 756 million short tons of coal were produced, according to estimates by the Energy Information Agency (EIA).  Despite this reduction in annual production, the EIA projects that coal will continue to provide fuel to generate approximately 25 percent of the electricity used in the U.S. The generation of electricity continues to account for the consumption of over 92 percent of coal mined in the U.S. The use of coal to produce coke for steel making, as well as other industrial, commercial, and institutional uses, accounts for the remainder of U.S. coal consumption.

There are numerous coal beds, of varying thickness, extent, and quality, in coal fields and basins spread throughout the U. S. - these compose the total coal resources of the nation. However, not all the total coal resources can be extracted. The portion of the total coal resources that may be able to be extracted are defined as recoverable coal resources. Recoverable coal resources are calculated by subtracting coal resources lost due to previous mining activities, exposure to weathering along outcrops, geological conditions, environmental, land use, or societal restrictions, and mining technology limitations from the total coal resources.

Reserves are the portion of the recoverable coal resources that can be extracted economically at a time of classification. The portion of recoverable coal resources that can be defined as reserves will vary over time, based on fluctuations in mining costs, differences in mining methods, and the market value of the coal.

In energy assessments, it is important to estimate not only the total coal resources, but to inventory the recoverable coal resources and coal reserves as well. Estimating the available coal resources and reserves provides a more accurate appraisal of how much of the total U.S. coal resources are realistically available for extraction in the future.

There is often confusion in the use of the terms coal “resources” and “reserves”. The two terms are often used interchangeably, but there are significant differences in their definitions. The terms are defined, from USGS Circular 891, as follows:

 

Coal resources – include in-place tonnage estimates that are determined by summing the volumes for identified and undiscovered coal deposits, utilizing a specified minimum thickness.

Coal reserves – are a subset of coal resources that are classified as economically extractable at the time of classification, after considering environmental, legal, and technological constraints. The facilities for extraction do not need to be in place or operative at the time of classification.

To be classified as economically extractable, the current market value of the extracted coal must be greater than the total cost to extract it.

The task of the U.S. Coal Resources and Reserves Assessment Project is to conduct a systematic determination of recoverable coal resources and reserves, on a regional basis for all major coal provinces in the United States. This differentiates the current coal assessment project from previous generations of coal assessment projects, in which typically only total coal resources were calculated.

The Project is focused on defining coal resources and reserves in the Northern Great Plains and Rocky Mountain Coal Provinces, with an emphasis on determining coal resources and reserves on Federal lands. The first U.S. coal basin to be evaluated was the Powder River Basin (PRB) in Wyoming and Montana, because it has been the most productive coal basin in the United States over the past 25 years. The results of the PRB assessment were published in Professional Paper 1809 in 2015.

Currently, assessment studies in three separate areas of the Greater Green River Basin have been started – an assessment of the Little Snake River coal field and Red Desert area (in south-central Wyoming) is nearly completed; an assessment of the Yampa coal field in northwest Colorado is ongoing; an assessment of the eastern portion of the Rock Springs Uplift coal field in Wyoming is also ongoing.  The Greater Green River Basin was prioritized for assessment because it contains vast land areas controlled by the Federal government, large portions of the basin have not been formally assessed for coal resources, and previously proprietary drill hole data have become available for use in geologic modeling and economic evaluations.

Assessment priorities are being adjusted in response to changes in coal utilization patterns and markets.  Metallurgical coal and export coal products are increasing their market share, while thermal coals, used for domestic electric power generation are decreasing.  Areas under consideration for future assessment are the Raton Basin (metallurgical coal), Grand Staircase/Escalante (metallurgical coal), the Piceance Basin (thermal coal), and the Williston Basin (thermal coal).  

As part of the USGS Energy Resources Program, the U.S. Coal Resources and Reserves Assessment Project research efforts yield state-of-the art, digitally-based assessments that detail the quantity, quality, location, and accessibility of the Nation’s coal resources and reserves.  Recent software updates to state-of-the-art database and geologic modeling packages are enhancing the quality of current assessment studies.   

 

Current Coal Assessment Studies Methodologies:

An External Peer Review of the U.S. Geological Survey Energy Resource Program’s Economically Recoverable Coal Resource Assessment Methodology was conducted in 2005, utilizing experts from industry, academia, and other government agencies.  This peer review is available at: Open-File Report 2005-1076

The methodology currently utilized by the U.S. Coal Resources and Reserves Assessment Project can be divided into three distinct phases – data collection, data modeling, and calculation of resources and reserves. A generalized outline of the methodology utilized is shown below: 

Phase I: Data collection 

1. geologic–drill holes, measured sections, geophysical data – that show coal bed thicknesses, partings, interburden/overburden lithologies, or structure. 

2. restrictions–data that define factors that affect extraction of coal – environmental, land use, legal, and/or technical restrictions. 

3. societal–data defining state, county, and municipal boundaries, surface property ownership and usage, and coal and other mineral estate ownership. 

4. coal quality–data points that provide information on coal quality parameters. 

5. coal economics–data on coal market prices and costs related to equipment, operations, and facilities. 

Phase II: Data modeling 

1. correlation–establishing the stratigraphic position and lateral continuity of individual coal beds within the assessment area. 

2. geologic models–incorporate the available geologic data, correlations, and structural features for each coal bed into a geologic model. Determine which coal beds have the thickness, extent, and lateral continuity to be designated as significant–for resources and reserves calculation purposes. 

3. GIS models-utilize GIS capabilities to model restrictions and societal data to determine areas where coal extraction is not possible. 

4. Composite model–combine geologic and GIS models to produce a composite model of the geology, restrictions, and societal features. 

Phase III: Calculating resources and reserves 

1. resources calculations-use composite model to: a. calculate original resources for all significant coal beds b. calculate recoverable resources for all significant coal beds 

2. projected mine costs-utilize coal economics data to develop mining costs through economic studies. 

3. cost curve graphs-utilize estimated mining costs and coal market pricing data to generate cost curve graphs. 

4. reserves determination-interpreted from the cost curve graphs for all significant coal beds.

Fact Sheet Chart - U.S. Coal Resource and Assessment project

 

Related Links

USGS Links

USGS Frequently Asked Questions (FAQ) Pertaining to "Coal"

NCRDS State Cooperators

External Links

ASTM Committee D05 on Coal and Coke

U.S. Department of Energy Clean Coal Initiative

U.S. Energy Information Administration

International Committee for Coal & Organic Petrology (ICCP)

The Society for Organic Petrology (TSOP)

Society for Mining, Metallurgy, and Exploration (SME) – www.smenet.org

National Mining Association (NMA) – https://nma.org

 

 

 

Greater Green River Basin, Wyoming and Colorado Coal Assessment

The Greater Green River Basin (GGRB) is a large, irregularly shaped, intermontane desert basin in the Rocky Mountain coal region. The basin spans are large region encompassing southwestern and south-central Wyoming and northwestern Colorado. The GGRB contains several coal fields of economic importance and there are several active coal mines in the basin, utilizing both surface and underground mining methods. The structural geology is relatively complex, with intra-basin anticlinal features dividing the GGRB into several sub-basins. The coal beds in the GGRB were deposited in fluvial/deltaic and lacustrine paleoenvironments and are Late Cretaceous, Paleocene, and Eocene in Age.  

Because of its areal extent, the Greater Green River Basin has been divided into three separate assessments – Little Snake River coal field and Red Desert area (WY), Yampa coal field (CO), and Rock Springs Uplift coal field (WY). The Greater Green River Basin was prioritized for assessment because it contains vast land areas controlled by the Federal government, large portions of the basin have not been formally assessed for coal resources, and previously proprietary drill hole data have become available for use in geologic modeling and economic evaluations.

The coal resources and reserves assessment of the GGRB is part of the current generation of U.S. coal assessments that not only define the total coal resources, but also systematically determine the available coal resources and reserves for a region or basin. The determination of available coal resources show what coal may be available for extraction after environmental, land use, and technological restrictions are applied to the total coal resources. The determination of reserves from the available coal resources shows what coal is currently available to be economically extracted, based on market conditions and projected mining costs. Determining available coal resources and reserves are important factors to be considered in the development of a national energy policy and for providing energy security for the United States.

 

Powder River Basin, Wyoming Coal Assessment

In 2009, the USGS completed the first digital National Coal Resource Assessment (NCRA) of in-place coal resources. The current generation of U.S. coal assessments will not only be a refinement of the coal resources, but also the systematic determination of the regional coal reserve base in all the major coal provinces in the U.S. The reserve base provides not only estimates of coal resources that are currently economic (reserves), but what may become economic with current technologies (recoverable resources), which is important from a national energy security and policy standpoint. The first U.S. coal basin to be evaluated in this new assessment phase is the Powder River Basin, WY (PRB). The PRB is the single most important coal basin in the U.S. production-wise, supplying over 42 percent of the total coal produced in the U.S. in 2012.

USGS Professional Paper 1809, Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana, was published in 2015. It is the compilation of four USGS Open File Reports into a single publication, covering four different assessment areas in the PRB. Professional Paper 1809 provides an overview of the geology and reports the original resources for the entire PRB, as well as the available coal resources and reserves.

 

Coal Quality

The USGS Energy Resources Program researches and provides studies on the quantity, quality, and location of the Nation’s coal resources and has world class research facilities investigating coal petrology and coal quality. These studies address coal extraction, utilization and disposal issues, human health and environmental impact issues, and identify suitable resources for the Nation’s electric power generation.

 

 

Coal Databases

The U.S. Geological Survey Energy Resources Program has developed coal databases to monitor the location, quantity, and physical and chemical characteristics of U.S. coal and coal-related deposits.