Coal Bed Methane
Coal Bed Methane (CBM) is natural gas found in coal seams. It mainly consists of Methane (CH4) with minor amounts of nitrogen, carbon dioxide and heavier hydrocarbons like ethane.
CBM was wasted and vented out into the atmosphere during the initial years of mining resulting in greenhouse emissions. CBM was a serious safety hazard while conducting coal mining operations. However, CBM is a precious energy resource and an unconventional form of natural gas. Given the fact that country’s energy requirement will rise with growth and development, CBM being a clean source of energy has garnered global significance with the emergence of active CBM players like Canada, Australia, and India.
Exploitation of Coal Bed Methane and Oil & Natural Gas has been placed under the administrative control of Ministry of Petroleum. They are governed by Oil Fields (Regulations and Development Act, 1948) and Petroleum and Natural Gas Rules, 1959. The safety aspects are covered under the Oil Mines Regulation, 1984.
Advantages of CBM as a fuel
- CBM is an environmentally safe gas: Methane has been labelled as a Green House Gas (GHG) by United Nations Framework Convention on Climate Change (UNFCCC). Its global warming potential is 21 times more than that of the Carbon Dioxide. But CBM is considered as a clean fuel which on combustion emits only carbon dioxide and water. So, is not only considered as an efficient fuel.
- Using CBM as a fuel will halt its emission into environment and thus reducing emission of green house gas from coal mining.
- Extraction of CBM prior to coal mining activities makes mining activities safer by degassing the coal seams.
- Extraction of CBM would help in increasing the domestic gas production. Currently, contribution of CBM to domestic natural gas production is 1.6%.
CBM resources in India
India has fourth largest proven coal reserves in the world. So it has significant prospects for exploiting CBM. But as of now there is no data available related to the total prognosticated CBM resources in the country. The Ministry of Petroleum and Natural Gas in consultation with Ministry of Coal has identified around 26,000 sq.km area for the operation of CBM.
Some issues and limitations have been identified in areas where operations of CBM and coal mines are being carried out simultaneously. In such areas it is preferred that coal mine operators are an active participant in CBM activities so that the responsibilities with respect to safety are shared by both. The following are some of the issues with respect to the simultaneous operations of Coal Bed Methane and coal mining by multiple owners:
- There is a possibility of damage of gas wells due to blasting/caving/ subsidence of overlying strata, resulting in explosive atmosphere in coal mines during simultaneous extraction of coal and CBM in the same vertical boundary by two different owners.
- Multiple ownership for simultaneous exploitation may not be desirable for the life, health and safety of the workers employed in such mines.
- Simultaneous operation over the same leasehold area requires the development of Safe Operating Procedures (SOP) for each operation based on assessments of risks.
- Overlap issues with Coal Blocks/ Oil/ Gas/ Other projects on existing CBM blocks. For instance an Airport project has been permitted over na existing CBM block. This has hampered the progress of CBM development.
- Land Acquisition and Water handling problems. Land acquisition problems for CBM blocks are severe as it requires a large number of wells for effective drainage of CBM. Also some CBM Blocks are located in the tribal land areas in the states of Jharkhand, Chhattisgarh and Madhya Pradesh. CBM wells tend to produce large volumes of water during the initial period to lower the pressure in the coal seams. Disposing this water which has high salinity and total dissolved salts (TDS) constitutes a significant expense.
- Delay in grant of permission from state governments. Consent to operate (CTO) from state governments are delayed.
- Delay in grant of statutory clearances like environmental clearances.
- Availability of Gas Infrastructure and Gas grid: As the CBM fields are located in isolated areas, integrated gas pipeline infrastructure forms a critical issue. CBM Blocks in the states like Jharkhand, Chhattisgarh and Madhya Pradesh do not have any nearby industrial belt for local consumption of CBM.
Benefits of extracting methane before mining operations
- Enhances the productivity of coal because less slowdowns in production caused by gas.
- Reduction in dust concentrations due to reduction in velocity.
- Improves safety of mines due to the lower methane contents.
- Improved worker comfort.
- Reduction in fan operating costs due to the need of reduced air requirements for dilution of methane.