Cleaner Energy Production with Underground Coal Gasification - a Review

Coal is the most abundant fossil fuel. This was the fuel that launched the industrial revolution and has continued to grow in use. The conventional coal fired power generation system in India and elsewhere produces some of the world's lowest cost electrical power but this large scale conversion comes with an environmental penalty. In a typical system an overall efficiency of 30% to 35% is realized. Stricter governmental regulations on pollutant emissions and the need to improve process efficiency have led to the development of advanced power generation systems. Underground Coal Gasification (UCG) is one such system. This paper reviews the importance of clean energy production, the UCG processes, conditions for operation of UCG, gas clean up procedure and product gas. UCG activities in different parts of the world are discussed in brief. It reveals that UCG may be suited for lignite deposits that are occurring at greater depth in Tamil Nadu and Rajasthan, coal deposits occurring beyond 600 m depth in Gujarat and leftover coal in abandoned mines partially developed by bord and pillar method in many coalfields in India