COAL BED METHANE AS NATURAL GAS SUBMITTED BY

COAL BED METHANE AS NATURAL GAS SUBMITTED BY R. MOHANA VISHNU P. SUBARANJITHAN

CONTENTS • INTRODUCTION • USES OF METHANE • EXTRACTION OF COAL BED METHANE • UTILISATIONS • COAL BED METHANE PROJECT IN INDIA • CBM IN CAUVERY DELTA • IMPACTS OF COAL BED METHANE • CONCLUSION

INTRODUCTION To meet the rapidly increasing demand for energy and faster depletion of conventional energy resources. India with other countries is madly searching for alternate resources like coal bed methane (CBM), shale gas, gas hydrate. CBM is considered to be the most viable resource of these. The present paper discussed about the prospect of CBM as a clean energy source, difficulty involved in production of CBM, enhanced recovery techniques

USES OF METHANE Methane is important for electrical generation by burning it as a fuel in a gas turbine or steam generator. Compared to other hydrocarbon fuels, burning methane produces less carbon dioxide for each unit of heat released. Liquefied natural gas or LNG is natural gas (predominantly methane, CH 4) that has been converted to liquid form for ease of storage or transport. Power to gas is a technology which converts electrical power to a gas fuel In a highly refined form, liquid methane is used as a rocket fuel.

EXTRACTION OF COAL BED METHANE Coal bed methane extraction (CBM extraction) is a method for extracting methane from a coal deposit. The methane is adsorbed into the solid coal matrix and is released when the coal seam is depressurized. Methane may be extracted by drilling wells into the coal seam. The goal is to decrease the water pressure by pumping water from the well. The decrease in pressure allows methane to desorb from the coal and flow as a gas up the well to the surface. Methane is then compressed and piped to market.

UTILISATIONS Coal Bed Methane generally provides the highest concentration of methane recoverable from coal seams due to the lack of exposure to air from mining. Concentration levels of methane recovered via these techniques can often exceed 95%, making the gas suitable for use as a direct replacement for conventional natural gas in pipeline networks. This gas can then be pumped directly to homes and businesses for use in cooking and heating.

COAL BED METHANE PROJECTS IN INDIA The Government of India has received overwhelming responses from prospective producers with several big players starting operations on exploration and development of CBM in India and set to become the fourth after US, Australia and China in terms of exploration and production of coal bed methane. India is potentially rich in CBM. The major coal fields and CBM blocks in Indian are shown in Fig. The. Directorate General of Hydrocarbons of India estimates that deposits in major coal fields (in twelve states of India covering an area of 35, 400 km 2) contain approximately 4. 6 TCM of CBM.

Information provided in the EIA report on land use pattern S. No. Land Use % of Study area 1. Open Space 42. 05 2. Dense Vegetation 33. 63 3. Sparse Vegetation 15. 56 4. Agricultural Land 4. 47 5. Village Pockets 1. 92 6. River 5. 47 7. Lake 1. 15 Total =SUM(ABOVE)100. 0 0%

GLOBAL COAL BED METHANE PROJECTS The largest CBM resource bases lie in the former Soviet Union, Canada, China, Australia and the United States. However, much of the world’s CBM recovery potential remains untapped.

CBM IN CAUVERY DELTA The Kaveri delta coal-bed methane extraction project is currently undertaken by Great Eastern Energy Corporation Ltd (GEECL), a private company based in Gurgaon, Haryana. The project aims to extract methane gas from coal-bed using environmentally destructive method of hydraulic fracturing in the Kaveri river basin. The company received license to explore and extract CBM from Nagapattinam, Thanjavur and Thiruvarur districts which are the major rice cultivating area of Tamil Nadu. Farmers, environmentalist and experts are opposing the project and hence it is currently suspended by the Government of Tamil Nadu.

Total landscape: 691 sq. kilometers. Out of this, 24 sq. kilometers are allotted to extract lignite and the rest 667 sq. kilometers (1, 66, 210 acres) is for methane extraction.

IMPACTS OF COALBED METHANE Ground water being pumped out through bore wells would be contaminated in many ways. It may contain salt more than 5 times as of sea water. Other compositional elements typically seen in extracted coal bed water include: Major Cations (positively charged ions such as sodium, potassium, magnesium, & calcium) Major Anions (negatively charged ions such as chlorine, sulfate, & hydrogen carbonate) Trace Elements & Metals (iron, manganese, barium, chromium, arsenic, selenium, & mercury) Organics (hydrocarbons and additives).

Suppose if a well is being drilled for every 80 acre of land, then 2000 wells would be drilled. About 20000 gallon (75000 litres) of water will be taken out from each of the wells every day. The plan to pass such contaminated ground water through the network of river canals which double as irrigation and water drains, is very dangerous. Hydraulic fracturing raises serious concerns because of the chemicals being used and their impact on the local ecology.

Methane Migration into Aquifers The gas wells themselves are the most common pathway for methane migration (leakage). This can lead to high levels of methane in streams, aquifers and eventually water.

Road Damage, Subsidence & Earthquakes Road damage is an inevitable consequence of CBM exploration due to intensive transportation of materials and machinery. Subsidence and earthquakes may be caused by the process and are quite common in conventional coal mining.

CONCLUSION Coal bed methane production is a rapidly growing industry that will undoubted continue to expand under the nation's demand for alternative energy sources. Water depletion from coal bed methane production can adversely impact adjacent residents, farmers and businesses that rely on local groundwater and surface waters. While the use of cleaner energy sources must be encouraged, such development should not proceed to the detriment of local communities.

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