Highly flammable sedimentary rock that is black or brown-black in color, coal is found in rock layers and in layers that are called the layers of coal. harder forms of rock, such as anthracite coal are considered a metamorphic rock due to exposure to elevated temperature and pressure.
Coal Composition
The coal is generally of the following components -
• Carbon;
• Sulfur;
• Oxygen;
• Nitrogen and
• Hydrogen.
Coal Evolution
From layers of plant matter that accumulates in the bottom of the water, being protected against biodegradation and oxidation, which are formed into coal. One place to provide the ideal climate for such periods Carboniferous shallow sea is wide. Deeply buried in soil sediments such vast peatlands were covered and buried deeply and turned into charcoal. Over time, the chemical and physical properties of litter are modified to form the solid material. This solid material is coal.
Features of Coal
• Coal is one type of fossil fuel;
• It is the largest source of energy for electricity generation throughout the world;
• It is also one of the largest anthropogenic sources of emission of carbon dioxide;
• Carbon die oxide emissions from coal is higher than emissions in petroleum;
• Coal is mined from underground or open crust pits.
Use of Coal for Electricity Generation
Primarily used as solid fuel for production of electricity as well as heat through the process of combustion, consumption of coal was around 7,280,000,000 by 2010. China is the largest producer of coal followed by India. Maximum usage of coal was in United States for electricity generation where 90% of the coal produced or imported was used for the purpose.
Pulverization and Combustion of Coal
For generation of electricity and heat, coal is pulverized and combusted either in a furnace or with a boiler. Furnace heat converts boiler water into steam that is used to spin turbines turning generators creating electricity. Over the years the thermo dynamic efficiency of the process has increased a lot.
While scientists are trying to find out divergent alternative sources for power, till date coal continues to be the major source of energy on the planet earth.