Coal is a non-renewable source of energy and a fossil fuel without which is hard to imagine the world could function at the way it does today. Today coal is the second energy source in the world to produce primary energy. Coal has high importance in the electricity production and production of steel and metals. Year by year the global demand for energy is growing, mostly in economies who rapidly develop and industrialize, and also problems related to energy security are becoming increasingly important. Coal is considered a safe source of energy in energy production because its reserves in the world are large, and the price is more acceptable than other fossil fuels. The conversion process of coal into electricity takes place in thermal power plants where, during the combustion of coal, comes to greenhouse gas emissions into the atmosphere which contributes to climate change. Due to the pollution caused by coal, the world is increasingly turning to the production of energy from renewable energy sources, but the generation of electricity from coal currently cannot be replaced by renewable energy because of its high dependence on weather conditions and financial investment. In recent years, there has been an increasing reference to the production of "clean coal energy" to make it feasible, many methods are being developed and applied which leads to it. Over 70% of the world's coal production and consumption takes place in Asia, where China is the largest consumer and producer of energy, which most energy producing from coal, because of availability and price.