With reference to two non-conventional energy sources called ‘coalbed methane’ and ‘shale gas’, consider the following ‘statements: (1). Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks. (2). In India abundant coalbed methane sources exist, but so far no shale gas sources have been found. Which of the statements given above is/are correct?

The correct answer is D, because both statements are wrong.

Statement 1 gets both gases wrong. Coalbed methane (CBM) is mostly methane, but it is not chemically pure. It is held in coal seams, adsorbed on the coal matrix, and is released by drilling and dewatering the seam. Shale gas is also predominantly methane, trapped in fine-grained shale rocks. It is not a propane-butane mixture. Propane and butane are the main constituents of LPG, not of shale gas.

• Statement 2 is wrong because India does have shale gas prospects. Basins such as Damodar, Cambay, Krishna-Godavari and Vindhyan have been identified for exploration, and ONGC and OIL have worked on them. So the claim that no shale gas has been found is incorrect.
• CBM occurs in Damodar, Raniganj, Jharia and Cambay basins. Calling it abundant was a stretch in 2014, and its commercial viability is still a matter of assessment.

Core concept: unconventional hydrocarbons, where gas is trapped in source rock or coal rather than in porous conventional reservoirs. Mains link: GS III, energy security and the push towards a gas-based economy.

Trap: assuming shale gas is LPG-like, or assuming that CBM presence rules out shale gas in India.