The term "coal" describes a variety of solid, combustible rock material. Coal is the result of layers upon layers of dead plant material being transformed through intense heat and pressure over millions of years. All coal looks like a black, sometimes brownish or grayish, flaky rock material. Coal may be found underground and is often mined to be brought to the surface and burned as an energy source. Coal is primarily made up of the carbon that was once bound up in living plant material, but other elements like sulfur, hydrogen, and oxygen may also be present in a sample of coal. Many people are critical of using coal as a fuel source because it produces high levels of carbon dioxide.
There are four sub-types of coal, which are classified according to their carbon and moisture content. From highest to lowest in carbon content, these are anthracite, bituminous, subbituminous, and lignite coal.
No comments:
Post a Comment