Methane is the primary energy source of natural gas. Coal bed methane (CBM) is the methane gas found in coal seams. According to the International Energy Agency (IEA), by 2030, coal-based power generation is projected to more than triple. Despite competition from natural gas, coal is likely to provide 33 per cent of global electricity generation. Over 58 per cent of the world’s recoverable coal reserves are located in the United States (27 per cent), China (13 per cent), India (10 per cent) and Australia (8.7 per cent). And all these countries are now looking at exploring for CBM. Currently, natural gas from coal beds accounts for approximately 8 per cent of total natural gas production in the US. The resource potential of CBM in India has been conservatively estimated at 850 billion cubic metres. Methane is seen as an alternative gas for meeting local gas needs. As India’s gas demand rises, CBM and coalmine methane (CMM) will be able to compete favourably with imported coal, gas, or LNG on a fuel cost basis for power generation. From an environmental standpoint, use of CBM also makes sense. India’s heavy reliance on coal, much of it low quality, is a major cause of the country’s air pollution and relatively high carbon intensity level.

• How is amount of methane gas in a region estimated?

One method of estimating recoverable methane gas from a coal seam is estimating methane reserves by boring to the top of the coal seam, then extracting a core from the coal. The amount of methane recovered from the coal core is used to estimate gas content per unit volume of coal. If a number of cores are drilled and methane gas release is observed, one can estimate the amount of gas available in a region. The other method is through a series of calculations based on information already known about the coal in the region and the feasibility of CBM development.

• How is methane extracted?

Since CBM travels with ground water in coal seams, extraction of CBM involves pumping available water from the seam in order to reduce the water pressure that holds gas in the seam. CBM has very low solubility in water and readily separates as pressure decreases, allowing it to be piped out of the well separately from the water. Water moving from the coal seam to the well bore encourages gas migration toward the well.

• What is the current status of coal-bed methane exploration in India?

The coal-bearing formations of India occur in two distinct geological horizons in the lower Gondwana (Permian) belts of India and the tertiary sediments (Eocene-Oliocene) of north-eastern India, Rajasthan, Gujarat, and Jammu and Kashmir. Methane gas is entrapped within these formations at a wide range of sub-surface depths. CBM possibilities exist mainly in coalfields of the eastern region though there are promising mines in the Godavari basin and Barner basin (lignite) in the West. India formulated its CBM policy in 1997 and according to a memorandum of understanding between the coal ministry and the ministry of petroleum and natural gas, llotment of CBM blocks was started. So far three rounds of bidding have taken place, with the petroleum ministry inviting offers for 10 CBM blocks in the third round on February 27, 2006, the contracts for which have just been awarded.

• Besides being an energy source, are there other positives to India of CBM?

Apart from its energy possibilities, coal-bed methane offers incentives like carbon credits. While CBM extraction opens up new energy possibilities, especially at the pithead of mines, it is the recovery of the gas from running mines that carries exciting potential such as qualifying for carbon credits under the Clean Development Mechanism of the Kyoto Protocol, besides paving the way for generating energy in an environment-friendly manner.