Underground coal gasification
Also called: UCG · Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Beyond NCERT
Meaning
Underground coal gasification (UCG) turns coal into gas while it is still deep in the ground. The coal is never mined. Two wells are drilled into the coal seam, which is a buried layer of coal. Air or oxygen, along with steam, is pumped down one well. This makes the coal burn only partly, and the result is synthesis gas (syngas), a mix that is mostly carbon monoxide and hydrogen. The gas rises through the second well. It can be used to make power, fertiliser or chemicals. UCG matters because it can use coal that is too deep, too thin or too costly to mine. Its main risks are polluted groundwater and the ground sinking above the burnt-out seam.
Example
At Angren, near Tashkent in Uzbekistan, underground gasification has run since Soviet times. The gas it makes feeds a nearby power station.
Don't confuse with
- Surface coal gasification: in this method coal is first mined and then turned into gas inside a gasifier at a plant above ground. India's ₹37,500 crore scheme approved in May 2026 covers only surface gasification, not UCG.
- Coal-bed methane: this is methane gas that is already trapped in coal seams, and wells simply draw it out. The coal itself is not burnt or changed. India's first commercial output came from Raniganj in 2007.