U.S. Geological Survey Circular 1143
Coal—A Complex Natural Resource
An overview of factors affecting coal quality and use in the United States
With a contribution on coal quality and public health
Coal is abundant in the U.S., is relatively inexpensive, and is an excellent source of energy and byproduct raw materials. Because of these factors, domestic coal is the primary source of fuel for electric power plants in the U.S., and will continue to be well into the 21st century. In addition, other U.S. industries continue to use coal for fuel and coke production and there is a large overseas market for high-quality American coal.
Because humans have used coal for centuries, much is known about it. The usefulness of coal as a heat source and the myriad of byproducts that can be produced from coal are well understood. The continued and increasingly large-scale use of coal in the United States and in many other industrialized and developing nations has resulted in known and anticipated hazards to environmental quality and human health. As a result, there is still much to be learned about the harmful attributes of coal and how they may be removed, modified, or avoided to make coal use less harmful to humans and nature. These issues of coal quality have not been examined carefully until recently.
|Chunk of Texas subbituminous coal in the field. Pen for scale. Note the very thin, light-colored laminations that indicate bedding. Top-left enlargement is an example of a scanning photomicrograph showing minerals in coal. The bright-white, oval-shaped fragment is a pyrite framboid; the bright-white triangular fragment is zircon; each fragment is about 10 microns wide. The light-colored, equant blebs are quartz grains. They are set in a light-gray matrix consisting of coal macerals and a variety of clay minerals. Top-right enlargement is an example of a transmitted-light photomicrograph showing various coal macerals (organic components) such as vitrinite (dark reddish orange); liptinite (yellow and light orange); and fusinite, inertinite, and minerals (black). View is about 200 micrometers wide.