Ajay K. Singh and Amalendu Sinha Co 2 Storage Potential in Unmineable Coal Seams in India Central Institute of Mining and Fuel Research (Erstwhile Central Mining Research Institute) Barwa Road, Dhanbad – Speaker Ajay K. Singh

CO 2 Sequestration in Geologic Formations One of the options for mitigating the GHG effect is to sequester CO 2 in geologic formations. The geologic formations are i. Depleted oil and gas reservoirs ii. Use of CO 2 in EOR. iii. Deep unmineable coal seams iv. Use of CO 2 in enhanced CBM recovery v. Deep saline water-saturated reservoir rocks vi. Other suggested options (basalts, oil shales, cavities)

Coal - a porous rock

Methane adsorption

Carbon dioxide adsorption

Gas sorption in coal

Reservoir simulation

Coal and Lignite Deposits in India Gondwana -Nearly 99.7 per cent bituminous to subbituminous coal of India is available in the Lower Gondwana in the eastern region of India located in West Bengal, Jharkhand, Madhya Pradesh, Chhattisgarh, Orissa, Andhra Pradesh and Maharashtra provinces. Tertiary -Tamilnadu, Kerala, Gujarat and Himalayan foot hills from Pir Panjal of Jammu and Kashmir to Abor Hills and Kuen Bhum range of Arunanchal Pradesh. Deep seated lignite in region of Kalol of Cambay basin, Gujarat and Barmer–Sanchor basin in Rajasthan.

Geological Resources of coal as on in India (By GSI) StateCoal resources in Million tons ProvedIndicatedInferredTotal Andhra Pradesh Arunanchal Pradesh Assam Bihar00160 Chhattisgarh Jharkhand Madhya Pradesh Maharashtra Meghalaya Nagaland Orissa Uttar Pradesh West Bengal Total

Potential Coalbeds for CO 2 Storage in India The potential sites for CO 2 storage in coalbeds of Indian basins have been identified with due consideration of accepted exploration norms, depth wise resource distribution quality wise abundance and mining status of coal. Identified candidates for CO 2 storage in India. Category of coal bedsGrade of coalCandidates /Basins Unmineable Coalbeds in explored areas Power Grade coalSingrauli Mand Raigarh Talcher Godavari Grey Areas CoalbedsCoking coalJharia East Bokaro Sohagpur South Karanpura Superior non coking coalRaniganj South Karanpura Power grade coalTalcher Concealed CoalfieldsTertiary age coalCambay basin Barmer Sanchor basin* Power grade coalWest Bengal Gangetic Plain Birbhum Domra Panagarh Wardha Valley Extension Kamptee basin Extension

Comparative Adsorption of CO 2 and Methane Studies conducted so far supports stronger affinity of CO 2 to the coal molecule. 2 to 3 molecules of CO 2 may displace one molecule of methane It means carbon dioxide is preferentially adsorbed onto the coal structure over methane (2:1 ratio). Methane sorption capacity for Indian coals has been investigated by CIMFR. Understanding controls on CO 2 and CH 4 adsorption in coals is important for the modeling of both CO 2 sequestration and CBM production.

Methane and CO 2 Adsorption Isotherm Methane Adsorption (actually measured) Estimated CO 2 Adsorption cc/g Pressure (atm) Moisture Equilibrated cc/g

Properties of Potential Coalbeds Proximate analysis and rank of Unmineable and Grey area coalbeds. CoalfieldsBasic parameters (mmf basis) Other properties Reflectance VRo% VM (%) FC (%) East Bokaro South Karanpura Jharia -Barakar Raniganj Rajmahal-Barakar Singrauli- Barakar Sohagpur Pench valley Wardha valley Godavari Valley Talcher *mmf - Mineral matter free basis

Properties of Potential Coalbeds Proximate analysis and rank of Concealed coalbeds. CoalfieldsBasic parameters (mmf basis) Other properties Reflectance VRo % VM (%) FC (%) Cambay basin Barmer Sanchor basin W Bengal Birbhum Wardha valley Kamptee Kanhan valley *mmf - Mineral matter free basis

Unmineable Coalbeds in explored areas In depth coal resource analysis of Indian territory as per quality, depth wise distribution and status of exploration has supported in identification of suitable sites for CO 2 sequestration. The resources reported by GSI and other agencies have been classed as mineable and unmineable on the basis of the following factors. - Exploration limit of coal has been to 1200m depth cover. - Coking and superior grade non coking up to the explored limit has been classed as mineable. - Inferior grade non coking coal (Grade E-G) upto 900m depth cover in Damodar and Mahanadi Valleys have been taken as within mineable limit. - Mineable limit for inferior grade non coking coal of Godavari and Wardha Valleys have been taken as 800m due to premium pricing structure.

Unmineable coal and CO 2 storage capacity Coalfield Estimated adsorption capacity of CO 2 (m 3 /t) Unmineable Coal Reserve (Mt) CO 2 storage capacity (Bm 3 ) CO 2 storage capacity (Mt) CO 2 storage capacity (50%) (Mt) SingrauliRange 18.0 – 22.0 Average Mand RaigarhRange Average TalcherRange Average GodavariRange Average

Grey Area Coalbeds The extension of coal beds below 1200m depth cover in coking and superior grade non coking coal have not been explored even though the continuity of the coal beds was well indicated within the lineament. The coal beds of such zones beyond mineable limit have been classed as Grey Area reserve. These reserves in case of East Bokaro, South Karanpura, Jharia and Raniganj and Sohagpur are below 1200m depth cover while in case of inferior grade non coking the limit is 600m for Son Mahanadi Valley and 800m for Wardha Godavari Valley coal fields.

Grey Area Coalbeds CoalfieldEstimated CO 2 adsorption capacity (m 3 /t) Cumulative Coal seam thickness (m) Block Area (km 2 ) Coal Reserve (Bt) CO 2 storage capacity (Bm 3 ) CO 2 storage capacity (Mt) CO 2 storage capacity (50%) (Mt) South Karanpura Range Average East BokaroRange Average JhariaRange Average RaniganjRange Average SohagpurRange Average TalcherRange Average Grey Area coal reserve and CO 2 storage capacity

Concealed Area Coalbeds The coal beds not covered in resource estimation exercise because of the basalt trap or thick alluvium beds have been classed as concealed coalbeds. Invariably such beds come under chance discovery during oil and natural gas exploration or drilling for some special missions. The bottom most coal bearing Barakar formation in such operations has been located within 300m to 3km depth cover over Nagaland to Cambay Basin Gujarat. Concealed Gondwana Sediments in Gangetic Plain Barmer-Sanchor basin

Continued….. CoalfieldEstimated adsorption capacity of CO 2 (m 3 /t) Cumulative thickness of the coal seams (m) Area of the block (km 2 ) Coal reserve (Bt) CO 2 storage capacity (Bm 3 ) CO 2 storage capacity (Mt) CO 2 storage capacity (50%) (Mt) Cambay basinRange Average Barmer- Sanchor Basin Range Average W.B. Gangetic plain Range Average Birbhum coalfield Range Average Domra Panagarh Range Average Wardha Valley extension Range Average Kamptee Extension Range Average Concealed area coal reserve and CO 2 storage capacity

Quantity of CO 2 Storage in Indian Coalbeds CoalfieldCO 2 storage potential in Mt with 90% saturation level Total-Mt Unmineable bedsGrey areasConcealed areas East Bokarox84.94x85 South Karanpurax36.33x36 Jhariax71.20x71 Raniganjx41.57x42 Singrauli1.32xx 1 Sohagpurx36.70x37 Mand Raigarh2.67xx 3 Talcher x118 Godavari-Ramgundam67.75x?68 Cambay Basinxx Barmer Sanchor basinXx W. Bengal Gangetic Basin xx Birbhumxx Domra Panagarhxx Wardhaxx Kamptee Coalfieldxx Total4459 CO 2 storage capacity in Indian Coalfields

CO 2 point Sources and Compatibility of Unmineable Coalbeds The identified sites are estimated to have 4459 Mt CO 2 storage potential, sufficient to store over 20% of total gas emission from the present power plants over their life time. The sites close to the operating thermal power units may be the most appropriate for CO 2 sequestration as the transportation cost of the gas will be minimum and the pollution level of CO 2 is alarming (Bradshaw, 2002 and 2003). The rate of CO 2 generation and total CO 2, generated within the life span of a thermal power station; presuming 20 years more from the date. The sites with storage capacity below 12Mt have been ignored because of their insignificant size.

CO 2 storage capacity and point source gas generation in close vicinity CandidateCO 2 storage capacity (Mt) Nearest Point Source CO 2 generation Mt in life time (20 yrs) t/dayMt/year Cambay Barmer Sanchor Godavari East Bokaro South Karanpura Birbhum Domra Panagarh West Bengal basin Jharia Talcher Sohagpur Raniganj Continued…..

Conclusion CO 2 sequestration potential in Indian coalbeds is estimated to be 4459 Mt. Indian coalbed are classified into grey, concealed and unmineable based on its depth of occurrence and grade characteristics. The storage potential howsoever small may help in minimizing the GHG pollution level. Storage of CO 2 in coal seams may have an added advantage of enhanced CBM recovery.

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