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National Coal Quality Inventory (NaCQI) and U.S. Geological Survey 

Coal Quality Databases

Figure 1. Coal production in the United States, from 1950 projected 

through 2020. Data from the Energy Information Administration (1997a, b).

National Coal Quality Inventory (NaCQI)

Coal will remain a very significant part of U.S. energy 

needs (fig.1), even though there will continue to be 

concern about environmental impacts associated with 

its use. Currently, about 88 percent of U.S. coal 

production is used by electric utilities. The remaining 

12 percent is either exported or used domestically for 

other industrial applications, such as coke for steel 

production.

Debates generated by the 1990 Amendments to the 

Clean Air Act have highlighted the critical need for 

current, accurate, reliable, and comprehensive 

information on the quality of our domestic coal 

resources. To address this need the U.S. Geological 

Survey (USGS), the Electric Power Research Institute 

(EPRI) and its member utilities, geological surveys in 

coal producing states, and the Department of Energy’s 

Figure 2. Periodic table of the elements highlighting elements of environmental, human 

health, and technological concern, as well as elements having economic byproduct potential. 

Most of the highlighted elements and about 30 others are part of the current USGS analytical 

scheme used for analysis of coal samples collected for NaCQI.

Federal Technology Center (FETC) have 

created the National Coal Quality 

Inventory (NaCQI). The overall 

objective of this partnership is to 

generate reliable, accurate, and 

accessible information on the quality of 

the major coal beds that will be mined in 

the U.S. during the next 20-30 years. 

The new, comprehensive coal-quality 

database will augment the existing coalquality database (COALQUAL) 

maintained by the USGS.

The participants in this partnership 

(USGS, EPRI, FETC, state geological 

surveys, participating utilities, the 

Environmental Protection Agency, and 

the National Mining Association) are 

prioritizing the major coal-producing 

beds based on anticipated production 

trends, regional economic significance, 

and available coal-quality data. The 

sampling strategy is intended to obtain a 

balance of sample types (core/channel, 

run-of-mine, raw/clean, power-plant 

feed) to better represent coal to be used 

in the future. A schedule has been 

developed for the collection, handling, 

and characterization of the coal samples. 

Printed on recycled paper U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet FS-120-99

May 1999
Figure 3. Coal sample localities from COALQUAL (the U.S. Geological 

Survey geochemical database), July 1994. COALQUAL is part of the USGS 

National Coal Resources Data System. 

The current USGS analytical scheme will 

constitute the basic characterization of 

each sample. This scheme includes 

determining moisture, ash, heat value, 

sulfur forms, ash fusion temperatures, 

and the concentrations of about 60 major, 

minor, and trace elements (fig. 2). ASTM 

standard coal characteristics (for 

example, carbon, hydrogen, nitrogen, 

oxygen calorific value, and sulfur form 

data) will be generated by either 

commercial laboratories or by 

participating utilities. Additional sample 

characterization (for example, 

mineralogy, modes of occurrence 

determinations, leaching behavior, 

fouling characteristics) will be used to 

address the specific coal-quality issues in 

different regions. Overall, the number of 

samples collected, the supplementary 

characterization, and the number of core 

samples obtained will be determined by 

the level of project funding. It is 

anticipated that at least 1,000 coal 

samples will be collected and analyzed 

under the NaCQI project.

Sample collection began in 1998; sample 

collection and characterization will 

require three years. University and other 

coal research organizations will 

participate in NaCQI to help address 

relevant technological, environmental, 

economic, and geologic problems related 

to coal quality. NaCQI will follow 

uniform policies for respecting the 

confidentiality requirements of all 

participants.

Anticipated products of the NaCQI 

project will have importance on a 

national scale. The data resulting from 

NaCQI will lead to better understanding 

of patterns and trends of coal 

characteristics on a regional scale for 

each of the major coal basins. This 

knowledge should result in more reliable 

prediction and planning for developing 

the nation’s coal resources in a manner 

that will best safeguard air and water 

quality.

Existing USGS Coal Quality 

Database

The data generated by the NaCQI project 

will augment the coal quality 

information collected by the USGS since 

the mid-1970’s (fig. 3).

The USGS maintains COALQUAL, the 

largest existing database that contains 

coal-quality information on U.S. coal 

beds. The database is available as a 

USGS Open-File Report (Bragg and 

others, 1998). Information in this 

database can be used to locate coal 

having quality characteristics desirable 

for specific technological uses and for 

environmental compatibility.

International Coal Quality 

Database

The USGS, in cooperation with many 

coal-producing countries, will create a 

database that contains coal-quality 

information on an international basis. 

The primary focus of this effort will be to 

obtain information on the quality 

characteristics of coal beds which are 

currently being mined and burned in 

other countries. The database will 

provide coal-quality information 

beneficial to the source country as well as 

to U.S. companies interested in finding 

markets for coal-related products and 

services. The information contained in 

this database will also provide a more 

accurate picture of the composition of 

emissions from coal burning, worldwide.

References

Bragg, L.J., and others, 1998, U.S. 

Geological Survey Coal Quality 

(COALQUAL) Database; Version 2.0: 

U.S. Geological Survey Open-File 

Report 97-134, available on the World 

Wide Web at URL 

http://energy.er.usgs.gov/

products/databases/coalqual/intro.htm.

Energy Information Administration, 

1997a, Annual Energy Review 1996: 

U.S. Department of Energy report 

DOE/EIA-0384 (96), 400 p.

Energy Information Administration, 

1997b, Annual Energy Outlook 1998: 

U.S. Department of Energy report 

DOE/EIA-0383 (98), 227 p.

Dr. John E. Repetski

U.S. Geological Survey

926A National Center

Reston, VA 20192

Phone: 703-648-5486

Fax: 703-648-5420

jrepetski@usgs.gov

For more information, please contact:

Dr. Robert B. Finkelman

U.S. Geological Survey

956 National Center

Reston, VA 20192

Phone: 703-648-6412

Fax: 703-648-6419

rbf@usgs.gov

USGS Energy Program website:

http://energy.usgs.gov