Available online at www.sciencedirect.com ScienceDirect

Energy Procedia 90 ( 2016 ) 336 – 348

5th International Conference on Advances in Energy Research, ICAER 2015, 15-17 December 2015, Mumbai, Fugitive methane emissions from Indian mining and handling activities: estimates, mitigation and opportunities for its utilization to generate clean energy

Ajay K. Singh∗, Jaywardhan Kumar

CSIR-Central Institute of Mining and Fuel Research, 826 015, India

Abstract

Fugitive methane emissions from fossil fuel extraction account for significant contribution towards greenhouse gas (GHG) emissions in India. Out of total all-India GHG emissions of 1.88 million Gg-CO2 equivalent in 2010 (with LULUCF), 48928.66 Gg-CO2equivalent belonged to fugitive emissions from fossil fuel extraction. Methane emission from and handling activities has increased from 0.555 Tg in 1991 to 0.765 Tg in 2012, as per national emission factors developed by CSIR-CIMFR. These estimates have been prepared as part of India’s Second National Communication to the United Nations Framework Convention on Climate Change (UNFCCC) and the Biennial Update Report (BUR).

With increasing demand of coal, current production is likely to touch around a billion tonnes by 2020. In this paper a time series data of coal production and associated fugitive methane emissions from coal mining and handling activities have been presented up to the year 2012. The methane released from coal mining and also coalbed methane can supplement India’s scarce natural gas reserves and act as a GHG mitigation opportunity. There are several technologies to achieve this in India, which include:

1. Coalbed methane (CBM): There exists an estimated potential of 400 BCM of CBM in three provinces viz. , and Chhatisgarh. Commercial scale exploitation of CBM has already begun in Coalfield in India. 2. Coal Mine Methane (CMM): Three coalfields in the Basin (Raniganj, and ) were studied for feasibility of recovery and utilization of CMM. Kalidaspur and Ghusick collieries in the , Murulidih, Amlabad, Sudamdih and Parbatpur mines in the and Jarangdih and Sawang collieries in the appear to be favourable sites for CMM recovery.

∗Corresponding author. Tel.: +91-326-2296007; fax: +91-326-2296025 E-mail address:[email protected]

1876-6102 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICAER 2015 doi: 10.1016/j.egypro.2016.11.201 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 337

3. Ventilation Air Methane (VAM): Methane diluted by ventilating air in underground coal mines is vented to the atmosphere and may be captured for its gainful utilization. Our studies have revealed that utilization of VAM at Mine of BCCL can lead to a net emission reduction of 0.62 million tonnes of CO2 equivalent per year. 4. Abandoned Mine Methane (AMM): There has been no effort to quantify the potential of AMM resource in India so far. It is imperative, therefore to initiate a study for evaluation of AMM resource potential in India.

Such mechanisms may serve as a valuable instrument to mitigate atmospheric methane emissions to the atmosphere and to find new pathways of clean energy deployment in India. This paper presents an analysis for policy-makers and the stake holders by providing a technological overview for augmenting clean energy resources in India.

© 20162016 The The Authors. Authors. Published Published by Elsevierby Elsevier Ltd. Ltd.This is an open access article under the CC BY-NC-ND license (Peer-reviewhttp://creativecommons.org/licenses/by-nc-nd/4.0/ under responsibility of the organizing). committee of ICAER 2015. Peer-review under responsibility of the organizing committee of ICAER 2015 Keywords:Coal mining and handling activities; Clean Coal Technology;Coalbed Methane; Coal Mine Methane

1. Introduction

In the last four decades, a substantial growth has been recorded in commercial primary energy consumption in India. Energy usage in India is expected to grow significantly due to India’s developmental goals. Though the renewable energy consumption has grown from 9.2 MTOE in the year 2011 to 13.9 MTOE in the year 2014 [1], coal is likely to remain the main source of in the foreseeable future [2]. It has been reported that over 70% of electricity generated in India is from thermal power plants [3]. Coal is considered as vital to India's energy security [4]. The Geological Survey of India [5] has estimated proven coal reserves of the country at 131.61 billion tonnes. Estimates of total coal resources are much higher at 306.60 billion tonnes up to a depth of 1200 metres as on 1st April 2015. The coal resources reported above are coal in-situ and all of them are not extractable at the present status of economics and technology. The proved recoverable reserves of 60.6 billion tonnes [6] are capable to supply coal for over 100 years at current level of production and more than 50 years at double the existing rate of production. This appears to be a very comfortable situation and should enable coal mining industry in India to meet increasing demand despite some technological and financial barriers. Methane is invariably found within coal seams and associated rocks. Coal normally stores substantial quantities of methane within its micro pores. Underground coal mining was plagued by the gas hazards and had been a continual source of anxiety and inconvenience to the miners throughout the long history of the industry [7]. The ventilation air along with the mine gases is released into the atmosphere. Although, the levels of methane in the vented air is frequently less than 0.02% in the Indian context, a significant amount of the gas is added to the atmosphere every year, as the quantity of vented air is quite large. Methane present in coal is not a safety problem in the case of surface mining. However, a considerable amount of the gas is emitted to the atmosphere during surface mining of coal also as the share of coal production from surface mines is more than 90% in India. Besides the emission during mining, coal still contains some remnant gas that is released slowly with time during handling activities such as processing in washeries and coal handling plants and subsequent utilization. In this paper, current methane emissions from Indian coal mining and handling activities have been estimated. The basic calculations for estimating emissions have been carried out following the methodologies very similar to those recommended by the Intergovernmental Panel on Climate Change (IPCC) [8, 9]. Methane emission factors during mining and post mining for different categories of coal mines have been determined. Annual coal production data for different category of mine is collected, which is multiplied by the corresponding methane emission factor and the conversion coefficient of 0.67 × 10-6 Gg m-3 to obtain estimates of methane emission from coal mining. Estimates based on IPCC emission factors have also been obtained and are compared with the present results. Besides the estimates of methane emission from coal mining and handling activities, various mitigation options for extraction of this gas for its gainful utilization as a clean source of energy have been discussed.

338 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

Nomenclature A Activity data AMM Abandoned mine methane BCM Billion cubic meters CBM Coalbed methane CMM Coal mine methane CO2 eq/year Carbon dioxide equivalent per year EF Emission factor GCV Gross calorific value Gg Gigagram GWP Global warming potential kJ Kilo joule kWh Kilowatt –hour m3 Cubic meter m3/min Cubic meter per minute m3/t Cubic meter per tonne MTOE Million tonnes of oil equivalent sq km Square Kilometre Tg Teragram VAM Ventilation air methane

2. Generation, storage and transport of methane in coal

Methane and small quantities of some other gases are native in coal seams. Various theories have been postulated to explain the physical and chemical changes during coalification [10, 11]. Some of them relied on the formation of methane, carbon dioxide, wet gases and water as the products of devolatilization during coalification [12]. The quantity of methane generated depends on degree of coalification and several other geological parameters. However, a large amount of gas (mostly methane) is stored in the micro porous network of coal. Coal is, therefore, both a source and reservoir rock for the gas. Most have large surface areas of about several hundred square meters per gram [13]. Micro-pores in coal through a microscopic view are shown in Fig 1.(a). Coal has a natural fracture system also called cleat that is formed during coalification with deplugging and devolatalisation of the Coal [14]. Two perpendicular sets of fractures termed as face and butt cleats are generally found in coal. Fractures and cleats which provide permeability for transport of gas in coal are shown in Fig. 1 (b). For a more detailed understanding of methane transport in coal reservoirs, the reader may refer to [15].

a b

Fig. 1. (a) Microscopic view of the micro-pores structure of coal, Reprinted with permission from Ref 16. Copyright 1994, American Chemical Society.(b) Fracture system and cleats in coal Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 339

3. Gassiness of coal seams in India

Based on mine specific measurement of rate of emission, all the underground coal mines in India have been categorized into Degree I, Degree II and Degree III by the Directorate General of Mines Safety [17]. “Degree I Seams” refer to a coal seam in which the percentage of methane in the general body of air does not exceed 0.1 and the rate of emission of methane does not exceed one cubic meter per tonne of coal produced. “Degree II Seam” means a coal seam in which the percentage of methane in the general body of air at any place in the workings of the seam is more than 0.1 or rate of emission of methane per tonne of coal produced exceeds one cubic metre but does not exceed ten cubic metres. “Degree III Seams” correspond to a coal seam in which the rate of emission of methane per tonne of coal produced exceeds ten cubic metres. Distribution of underground working mines having different degree of gassy seams in different states in India is shown in Table 1.

Table 1.Underground working mines having different degree of gassy seam ─ 2012. [18]

State Degree I Degree II Degree III Total Andhra Pradesh 41 ... … 41 Assam … …. 02 02 Chhatisgarh 42 ... 01 43 Jharkhand 61 26 07 94 Jammu and Kashmir 01 02 … 03 Madhya Pradesh 39 16 … 55 Maharashtra 22 … … 22 Orissa 07 03 … 10 West Bengal 24 56 03 83 All India 237 103 13 353

4. Methodology to estimate methane emission from coal mining and handling activities

The simple methodology defined in [8, 9] is represented in equation (1). Coal production data is considered as Activity data (A) which is multiplied by methane emission factor (EF) of respective category and the conversion factor of 0.67 × 10-6 Gg m-3 of methane to obtain estimates of methane emission from coal mining.

(1)

In order to obtain the methane emission factor, the following measurements were made in the underground mines of three different degrees of gassiness:

• The velocity of air passing through the return airways separately in each ventilating districts and in the main return of the mine with the help of Anemometer.

• Cross sectional area of each return airway of the mine by multiplying the average width and height of the airway.

• Percentage of methane in the air samples collected in the return airway of the mine by gas chromatography.

Quantity of air was calculated by multiplying the air velocity and cross sectional area of the return airway. This was further multiplied by the percentage of methane in the return airways to obtain daily make of methane in the mine. Daily coal production data was collected from the mine authority during the period of investigation. Methane emission factor was calculated by dividing the daily make of methane by the daily coal production [19]. 340 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

For surface mines a rectangular chamber (Fig.2) with internal dimensions of 50 × 40 × 15 cubic cm, closed from five sides but open floor and fitted with a nozzle for gas collection were used to measure methane flux. These chambers were placed on the benches of surface mines for a known period of time. Methane percentage inside the chamber was determined by gas chromatograph (Chemito, model number GC 1000). Area of freshly exposed coal face was also measured in the surface mines to calculate methane flux. Daily coal production data was collected during the period of investigation.

Fig. 2. Plastic rectangular chamber for methane flux measurement.

4.1. The activity data

Activity data on coal production from surface and underground mines was collected (See Table 2) [18]1.

Table 2.National coal production by type of mine workings in years 1990–2012 (in Million tonnes). Source: Ref 181.

Year Surface Underground (u/g) Total Coal Degree I Degree II Degree III Total u/g Production 1990 143.21 46.80 20.06 2.67 69.53 212.74 1991 167.03 44.92 22.56 3.25 70.73 237.76 1992 178.88 45.78 21.99 3.30 71.07 249.95 1993 186.94 49.62 20.48 3.58 73.68 260.62 1994 196.88 48.41 19.13 3.10 70.64 267.52 1995 216.07 46.59 18.95 2.97 68.51 284.58 1996 233.97 48.92 18.59 2.62 70.13 304.10 1997 247.62 48.53 17.98 2.55 69.06 316.68 1998 251.32 48.00 18.17 2.40 68.57 319.89 1999 247.09 47.22 18.61 2.26 68.09 315.18 2000 268.09 46.17 17.36 2.69 66.22 334.31 2001 277.38 45.97 15.73 2.43 64.13 341.51 2002 297.98 46.65 16.34 2.33 65.32 363.30 2003 315.56 45.64 16.13 1.86 63.63 379.19 2004 347.35 44.46 15.42 2.03 61.91 409.26 2005 356.76 44.03 18.18 1.88 64.09 420.85 2006 369.12 43.57 16.00 1.65 61.22 430.34 2007 387.33 44.87 17.43 1.86 64.16 451.49

1 Coal production data in respect of the underground mines are available from different categories of Degree I, Degree II and Degree III seams from the year 1980 onwards in the Directorate General of Mines Safety, Government of India publications for various years. Ref. [18] gives the reference of the statistics for year 2012. It may be noted that similar data has been used from the year 1990 onwards for this study. Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 341

Year Surface Underground (u/g) Total Coal Degree I Degree II Degree III Total u/g Production 2008 440.00 49.77 15.37 1.13 66.27 506.27 2009 491.98 53.76 12.17 0.89 66.82 558.80 2010 531.88 55.31 13.82 0.85 69.98 601.86 2011 538.24 55.40 11.54 2.08 69.031 607.27 2012 553.62 51.36 12.28 0.68 64.34 617.96

4.2. National emission factors for coal mining and handling activities

Emission factor for surface mining and also from underground mining for different degrees of gassiness are evaluated based on field measurement. These national methane emission factors for different categories of mines in India are presented in Table 3. These are also referred to as CSIR-CIMFR emission factors. These emission factors have been used for quantifying fugitive methane emission estimates, which has been reported in India’s Second National Communication to the United Nations Framework Convention on Climate Change (UNFCCC) and the Biennial Update Report (BUR) [20, 21].

Table 3. National emission factors for coal mining and handling activities in India. [20, 21] Operation (Mining/ Post Methane Emission factor (m3/tonne) Mining) Surface Mining Underground Mining Degree–I Degree–II Degree–III Mining 1.18 2.91 13.08 23.68 Post Mining (Handling) 0.15 0.98 2.15 3.12

However, the Intergovernmental Panel on Climate Change (IPCC) [8] has provided methane emission factors for low, average and high cases. These emission factors are the same as those described in [9] and are presented in Table 4.

Table 4. IPCC emission factors for coal mining and handling activities. Source: Ref. 9. Operation (Mining/ Post Methane Emission factor (m3/tonne) Mining) Surface Mining Underground Mining Low Average High Low Average High Mining 0.3 1.2 2.0 10.0 18.0 25.0 Post Mining (Handling) 0.0 0.1 0.2 0.9 2.5 4.0

It may be observed from Tables 3 and 4 that national methane emission factors for surface coal mining and handling activities are comparable to those of the average value of IPCC but the difference is significant, when we compare the national emission factors for underground coal mines with the values of IPCC default emission factors.

5. Results

Earlier estimates of methane emission such as [22] reported value of 0.4 Tg for the year 1990. In the present study, measurements have been made in 25 surface and 67 underground mines of different degrees of gassiness. Estimates for methane emission to the atmosphere were prepared for the years 1990 to 2012 is shown in Fig.3. These estimates were prepared using new emission factors determined in Indian context and also using the IPCC emission factors [8,9] for low, average and high cases. Coal production for the year 2012, emission factors and estimates of methane emission have been presented in the Table 5.

342 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

Table 5. Methane emission from Indian coal mining and handling activities for the Year 2012. STEP 1 STEP 2 A B C D E Amount of Emission Methane Conversion Methane Coal Factor Emissions Factors Emissions 3 3 Produced (m CH4/t) (million m ) (Tg CH4) (Million tonnes) CIMFR EMISSION FACTORS C = (A× B) E=(C × D) Underground Mining Deg. I 51.36 2.91 149.457 0.67x 10-6 0.100 Mines Deg. II 12.28 13.08 160.622 0.67x 10-6 0.107 Deg.III 0.68 23.64 16.075 0.67x 10-6 0.010 Post-Mining Deg. I 51.36 0.98 50.332 0.67x 10-6 0.033 Deg. II 12.28 2.15 26.402 0.67x 10-6 0.0177 Deg.III 0.68 3.12 2.121 0.67x 10-6 0.001 Surface Mining 553.62 1.18 653.271 0.67x 10-6 0.438 Mines Post-Mining 553.62 0.15 83.043 0.67x 10-6 0.0555 Total 0.765 IPCC EMISSION FACTORS Underground Mining Low 64.34 10 634.4 0.67x 10-6 0.431 Mines Average 64.34 18 1158.12 0.67x 10-6 0.777 High 64.34 25 1608.5 0.67x 10-6 1.079 Post-Mining Low 64.34 0.9 57.960 0.67x 10-6 0.0388 Average 64.34 2.5 160.85 0.67x 10-6) 0.107 High 64.34 4 257.36 0.67x 10-6 0.172 Surface Mining Low 553.62 0.3 166.086 0.67x 10-6 0.111 Mines Average 553.62 1.2 664.344 0.67x 10-6 0.445 High 553.62 2 1107.24 0.67x 10-6 0.743 Post-Mining Low 553.62 0 0 0.67x 10-6 0.00 Average 553.62 0.1 55.362 0.67x 10-6 0.0371 High 553.62 0.2 110.724 0.67x 10-6) 0.07431 Low 0.618 Average 1.425 High Emission 2.069 Emission Emission

Fig. 3. Trend of methane emission from coal mining and handling activities in India. Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 343

6. Mitigation strategies

From mitigation perspective, methane in coal may be recovered for its utilization. It has been identified as a clean fuel resource. The extraction technology of methane from coal mines is classified into the following three categories. • Coal Mine Methane (CMM) or Degasification of working seams: When methane is recovered simultaneously during mining of coal with an objective of reducing the methane concentration in the mine workings and for its utilization, it is known as coal mine methane. Various mine degasification techniques are followed to recover CMM [23].

• Ventilation Air Methane (VAM): Methane present in the ventilation air is known as the ventilation air methane. Although, the concentration of methane in the ventilation air is generally very low, new oxidation technologies have come up which burn the VAM and produce useful energy from it [24]. Ventilation air typically contains low and variable methane concentration and large quantity of the ventilation air make it difficult to handle and process it into useable forms of energy.

• Abandoned Mine Methane (AMM): Methane that continues to be emitted from the left over coal and the adjoining strata and is accumulated in the mine voids even after the abandonment of an underground mine, is known as AMM. The abandoned mines emit gas to the atmosphere through mine openings or factures that connect the mine void to the surface and through leaking or vented seals that are placed over ventilation shafts and other openings [25].

7. Options for methane recovery and energy generation

7.1. Coal mine project opportunities in some of the selected collieries in India

In a recent feasibility study funded by the US Environmental Protection Agency (US EPA), Kalidaspur and Ghusick collieries in the Raniganj Coalfield, Murulidih, Amlabad, Sudamdih and Parbatpur mines in the Jharia Coalfield and Jarangdih and Sawang collieries in the East Bokaro Coalfield appear to be promising sites for CMM recovery at first glance. CMM resources in the above collieries in the Damodar River Basin in India have been estimated and are presented in Table 6. Gas resources in Ichhapur [26], and Sitarampur blocks in the Raniganj Coalfield and Asnapani and Kathara blocks in the East Bokaro Coalfield have been estimated and are presented in Table 7.

Table 6. Important collieries for coal mine methane extraction. Name of the colliery Name of Coal field Degree of Mine CMM resource (Billion cubic meter) Kalidaspur Raniganj III 3.783 Ghusick Raniganj III 2.58 Murulidih Jharia III 4.98 Amlabad Jharia III 0.76 Sudamdih Jharia III 0.80 Central parbatpur Jharia III 5.31 Jarangdih East Bokaro III 4.87 Sawang East Bokaro III 6.31

Table 7. Important blocks for coal mine methane extraction. Name of the block Name of Coal field Area Status of the block CMM resource (Sq km) (Billion cubic meter) Ichhapur Raniganj 12 Virgin 3.83 Kulti Raniganj 7.8 Virgin 1.77 Sitarampur Raniganj 9 Virgin 1.63 Kapuria Jharia 6.4 Virgin 1.51 Asnapani East Bokaro 4 Virgin 6.64 Kathara East Bokaro 6 Virgin 8.62 344 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

Kalidaspur colliery is a degree III mine in the Raniganj coalfield with an average production of 350 tonnes per day. The rate of methane emission was found to be more than 10 cubic meters per tonnes of coal mined during the days of investigation. The maximum and minimum values of rate of methane emission per tonnes of coal production were 8.78 and 19.27 cubic meter per tonnes respectively. The CMM resource estimated for Kalidaspur Colliery including the adjoining virgin Bakulia Block was 3.783 billion cubic meters (BCM). Thus, it qualified to be a potential site for a small scale CMM project. Ghusick colliery is also a degree III underground coal mine in the Raniganj coalfield. This colliery was found with very high level of gas at shallow depth. During the investigation period it was found that make of methane varied between 11.02-14.2 m3/minute even when the production was only 70 tonnes of coal per day. Also the gases obtained from the sealed off areas, when analyzed were containing 50-65% of methane. An estimated CMM resource of 2.58 billion cubic meters (BCM) was found at the Ghusick colliery. Thus the venture of CMM degasification and Gob degasification can be accomplished at the Ghusick colliery. Ichhapur, Kulti and Sitarampur are the virgin coal blocks of Raniganj coalfield having a maximum value of in- situ gas content of 7.06 m3/t, 9.16 m3/t and 7.21 m3/t respectively. The CMM resource of Ichhapur Block was found to be 3.83 BCM and it is suitable for small scale CMM project. The total gas resource of 3.40 BCM is present in the Kulti and Sitarampur Blocks, therefore these blocks can be developed as a site for medium scale CMM project. In the Jharia coalfield, Murulidih, Amlabad, Sudamdih and Parbatpur are important collieries for CMM extraction. Murulidih mine lies in the sub-basin area and is designated as degree III mine. With a CMM resource of 4.98 BCM in the Raniganj and deep formations, Murulidih colliery can be considered for medium scale CMM project. Amlabad and Sudamdih Collieries also have high levels of gas, and at relatively shallow depths. Both the mines are Degree III gassy mines. The rate of methane emission is 25 m3/t of coal production at the Amlabad Colliery making it very difficult for coal mining. It has an estimated gas resource of 0.76 BCM. The nearby Sudamdih mine is having a gas resource of 0.80 BCM. Therefore these two collieries can be modeled as small scale CMM ventures. Central Parbatpur is located to the South of Damodar River in the South Eastern part of Jharia coalfield, covering an area of about 8.8 sq km. This area is characterized by significant tectonic disturbance and is cris-crossed by 11 major faults. Central Parbatpur is having a CMM resource of 5.312 BCM, representing a rich site for CMM extraction and recovery. East Bokaro Coalfield is a huge store house of high rank medium coking metallurgical coals. Jarangdih and Sawang are two underground Degree III collieries with known history of gassiness. The rate of methane emission per tonne of coal produced at Jarangdih 6 ft seam at the Jarangdih colliery mine was insignificant but a value of 17.12 m3/t methane emission was observed in the Jarangdih 6 ft seam at the Sawang colliery. Two important virgin blocks namely Asnapani and Kathara located in the south central part of East Bokaro Coalfield, having a surface area of 4 sq km and 6 sq km respectively provide an option for CMM extraction and recovery. The Asnapani block is containing a CMM resource of 6.64 BCM and Kathara Block with a CMM resource of 8.62 BCM can be easily chosen for CMM projects location.

7.2. VAM project opportunities in India

There are 13 degree III mines in India (Table 1) and wherein VAM utilization is feasible. CSIR-CIMFR along with Southern Illinois University Carbondale (SIUC), USA completed a study to evaluate the resource potential of VAM utilization at Moonidih and Sudamdih mines in the Jharia Coalfield [27]. Further studies were conducted by CSIR-CIMFR for assessment of quantity and quality of the mine air and characteristics of washery middlings at Moonidih mine of Limited which is a Degree III gassy mine and concentration of methane in the return air varies from 0.3 to 0.6%. Further, Moonidih Mine has its own washery and has surplus middlings too. Hence, Moonidih was chosen for feasibility study for implementation of Hybrid Coal Gas Technology (HCGT) developed by CSIRO, Australia wherein washery middling is combusted along with ventilation air methane in a rotary kiln to produce hot gas for production of electric power. The process includes collection of air with minimum 0.3% methane concentration at the rate of 12000 m3/min from the mine exhaust and feeding it to the rotary kiln where it may be combusted with washery middling at the rate of 11.75 tonne/hour. The hot gas coming out of the rotary kiln Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 345 will be supplied to a waste heat recovery boiler (WHRB). The steam produced by the boiler at the rate of 60 tonnes per hour will be used in a steam turbine generator which will produce nearly 12 MW power.

7.2.1 Calculation of net emission reduction for VAM project at Moonidih Mine

For calculation of net emission reduction, the input parameters are assumed as air flow rate from the return of coal mine is 12,000 m3/min and the concentration of methane in the return air as 0.5%. A significant reduction of 0.62 million tonnes of CO2 per year is possible with the use of VAM. The important parameters are reflected in the Table 8.

Table 8.Analysis of net emission reduction by using VAM for Moonidih coal mine. Sl.no Description Quantity Unit 1. VAM fed to Rotary kiln 12,000 m3/min 2. Average concentration of methane in VAM 0.5 % 3. Volume of methane consumption in rotary kiln 3.154x107 m3/year 4. Consumption of methane in rotary kiln 2.253 x104 tonnes/year 5. Net GCV with available methane quantity 1.0535x1012 kJ/year 3 (Considering GCV of CH4=33402 kJ/m ) 6. Heat available for power generation 2.739x1011 kJ/year (considering 26% efficiency) 7. Electricity generation with available heat 7.395x107 kWh/year (Considering 1kJ=2.7x10-4kWh) 4 8. CO2emission from grid for available electricity 6.063 x10 tonnes of CO2/year 2 (Considering CO2intensity of grid as 0.82 kgCO2/kWh) 4 9. CO2avoided by consuming methane 63.084 x10 tonnes of CO2/year 3 (considering GWP of CH4= 28) 4 10. CO2 generated due to combustion of CH4 in Kiln 6.195x10 tonnes of CO2/year 4 11. Net CO2 reduction by utilizing VAM 62.952x10 tonnes of CO2/year

The reader may refer to Appendix A for detailed calculation procedure of the results.

8. Conclusion

Coal production in India is dominated by surface mining. While production from surface mines is increasing annually, the underground production is almost stagnant. Methane emission to the atmosphere from coal mining and handling activities in the country has increased from 0.504 Tg in the year 1990 to 0.765 Tg in the year 2012. In some gassy mines, drainage of methane will be helpful in reducing methane concentration inside the underground mine, thus making safer working environment for the miners and reduction of downtime due to gas problems. As a result of lower emission of methane into the underground working, the air required for ventilation also gets reduced, thus, lowering the ventilation cost for the mine. The coalbed gas can be recovered and utilized for various uses depending on the quality and quantity of the gas produced. Moreover, the recovery and use of the CMM leads to reduction of emission of this greenhouse gas into the atmosphere and help in mitigation of a potent greenhouse gas. The reduction in emission of methane can be monetized and carbon credit can be earned. Though opportunities for CMM, VAM and AMM recovery and utilization do exist in some gassy mines in India to support alternative sources of clean energy and such options have the potential of contributing towards stabilization of atmospheric methane concentrations, exploitation of the gas is yet to begin mainly due to policy initiatives. It is imperative, therefore to formulate mechanisms for recovery and utilization of CMM, VAM and AMM in Indian coalfield.

2 CO2 intensity of grid in kgCO2/kWh has been obtained from Central Electricity Authority [28]. 3 Global warming potential (GWP) of CH4 is taken as 28 [29]. 346 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

Acknowledgment

The work was financially supported by the US EPA, Washington DC, USA and NATCOM Project, InsPIRE Network for Environment, New , India. Technical collaboration with Prof. Satya Harpalani, SIUC, USA and Prof. B.K. Prusty, IIT Kharagpur is gratefully acknowledged. Help and cooperation provided during the field investigation by the authorities of various coal companies is sincerely acknowledged. The authors thank Dr. Pradeep K Singh, Director, CSIR-CIMFR, Dhanbad, for his skilful guidance and kind permission to publish this paper. We sincerely acknowledge Udayan Singh, Mechanical Engineering Department, NIT Rourkela for his kind support while preparing this paper.

Appendix A. Calculation of net emission reduction using VAM

The calculation of net emission reduction potential of ventilation air methane (VAM) is shown in sub-section A.1.

A.1. Calculation of net emission reduction for VAM project at Moonidih Mine

Air flow rate from the evasee is 12000 m3/min that may be fed to the rotary kiln. Then the Air flow rate per annum = 12000×60×24×365 = 6307200000 m3/year

Considering the average concentration of 0.5% methane in VAM, methane consumption per annum will be (0.5×6307200000)/100 3 = 31536000 m CH4/year 7 3 =3.154×10 m CH4/year

This will be fed to one rotary kiln. Therefore, methane consumption per annum for one rotary kiln can be calculated as below: CH4 consumption per annum per rotary kiln 7 3 = 3.154×10 m CH4/year = 3.154×1010Liters/year = (3.154×1010/22.4) g-moles per year = (3.154×1010/22.4) ×16 gram/year = 2.2528×1010 gram/year = 2.253×104 tonnes/year

The complete oxidation of methane takes place, according to the following chemical reaction. CH4 + 2O2 → CO2 +2H2O It means 16g of CH4 produces 44g of CO2. 4 4 Therefore, 2.253×10 tonnes/year of methane will generate (2.253×10 tonnes/year) ×44/16 tCO2eq/ year = 61957.5 tCO2eq/ year 4 =6.195×10 tCO2eq/ year 4 Thus a quantity of 6.195×10 tCO2eq/ year will be generated by rotary kiln due to combustion of methane.

Now, GCV of methane = 33402 kJ/SCM Net GCV available =33402×3.154x107 kJ/year =1.0535 ×1012 kJ/year

Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348 347

Assuming an efficiency of 26%, the heat that is available for power generation = 0.26×1.0535 ×1012 kJ/year kJ/year = 2.739×1011kJ/year We know that 1 kJ = 2.7×10-4 kWh Therefore, electricity generation possible with the available heat per kiln = 2.739x1011×2.7×10-4 kWh/year = 73955635.42 kWh/year =7.395×107 kWh/year

7 If 7.395x10 kWh/year of electricity were purchased from the Eastern Region Grid of India, the amount of CO2 generated, considering the carbon intensity of grid as 0.82 kg CO2/kWh will be equal to 7 0.82×7.395x10 kg CO2 eq/year = 60639000 kg CO2 eq/year = 6.0639 × 104 tCO2 eq/year

Since the available 2.253×104 tonnes/year of methane will be consumed by the VAM based HCGT power plant 4 Therefore, an equivalent amount of 2.253×10 × 28 = 630840 tCO2eq/ year 4 = 63.084 ×10 tCO2eq/ year will be prevented from escaping to the atmosphere.

Net emission reduction will be: 4 4 4 (63.084 ×10 + 6.063 × 10 − 6.195 × 10 ) tCO2eq/ year. 4 = 62.952 × 10 tCO2eq/ year

References

[1] BP. BP Statistical Review of World Energy; 2015. [2] Chikkatur AP, Sagar AD, Sankar TL. Sustainable development of the Indian coal sector. Energy 2009;34: 942-953. [3] Central Statistics office. India Energy Statistics 2015Ministry of Statistics and Programme Implementation, Government of India. New Delhi; 2015.

[4] Garg A, Shukla PR. Coal and energy security for India: Role of carbon dioxide (CO2) capture and storage (CCS). Energy 2009; 34: 1032- 1041. [5] GSI. Inventory of Geological Resource of Indian Coal as on 1st April 2015. Geological Survey of India, , India; 2015. [6] Shankar U. Coal – Backbone of World Economy. In: 5th Coal Summit, New Delhi; 2014, p. 44-49. [7] Singh H, Singh AK. Coal mine methane as a mitigation option against gas hazards in underground coal mines. In: Singh AK, Vishwakarma RK, Ahirwal B, editors. Design, Development, Testing and Certification of ex-equipments. Dhanbad: CSIR-CIMFR; 2009. p.289-299. [8] Eggleston HS, Buendia L, Miwa K, Ngara T, Tanabe K, editors. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Kanagawa:IGES; 2007. [9] Houghton JT, Meira Filho LG, Lim B, Treanton K, Mamaty I, editors. Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. Paris:IPCC/ OECD/IEA;1997. [10] Teichmuller M, Teichmuller R. Geological Causes of Coalification, Coal Science, Advanced Chemistry Series 1966; 55:133-155. [11] Hatcher PG, Clifford DJ. The Organic Geochemistry of Coal: from plant materials to coal. Organic Chemistry 1997; 27: 251-274. [12] Eddy Greg E, Rightmire Craig T, Byrer Charles W. Relationship of methane content of coal rank and depth: theoretical vs. observed. In: SPE Unconventional Gas Recovery Symposium.Society of Petroleum Engineers; 1982. [13] Botsaris GD, Glazman YM. Interfacial Phenomena in Coal Technology. New York:Marcel Dekker; 1989. [14] Levine JR. Coalification: The evolution of coal as source rock and reservoir rock for oil and gas. In: Law BE, Rice DD, editors. Hydrocarbons from Coal, AAPG studies in Geology; 1993. p. 39-78. [15] Singh AK. Modeling methane transport in coal reservoirs. In: Singh AK, Mohanty D, editors. First Indo-US Workshop on Coal Mine Methane. Dhanbad: CSIR-CIMFR; 2011. p. 141-149. [16] Lin SY, Hirato M, Horio M. The characteristics of coal char gasification at around ash melting temperature. Energy &Fuels 1994; 8:598-606. [17] DGMS. The Coal Mines Regulations.Dhanbad:Directorate General of Mines Safety; 1967 [18] DGMS. Statistics of Mines in India Vol. I (Coal). Dhanbad:Directorate General of Mines Safety; 2012. [19] Singh AK. Methane emission from coal mining and handling activities in India. In: Mitra AP, Sharma S, Bhattacharya S, Garg A, Devotta S, Sen K, editors. Climate Change and India: Uncertainty Reduction in Greenhouse Gas Inventory Estimates. Hyderabad:University Press; 2004. p. 41-49. 348 Ajay K. Singh and Jaywardhan Kumar / Energy Procedia 90 ( 2016 ) 336 – 348

[20] MoEF. India Second National Communication to the United Nations Framework Convention on Climate Change. Ministry of Environment and Forests. Government of India; 2012. [21] MoEFCC. India First Biennial Update Report to the United Nations Framework Convention on Climate Change. Ministry of Environment, Forestsand Climate Change. Government of India; 2015. [22] Banerjee BD, Singh AK, Kispotta J, Dhar BB. Trend of methane emission to the atmosphere from Indian coal mining, Atmospheric Environment 1994;.28:1351-1352. [23] Prusty BK. Mine Degasification and Recovery of Coal Mine Methane – Worldwide Practice. In: Singh AK, Mohanty D, editors. First Indo- US Workshop on Coal Mine Methane. Dhanbad:CSIR-CIMFR; 2011. p.107-118. [24] Somers J, Collings R. Coal Mine Ventilation Air Methane: Project Development and Mitigation Option. In: Singh AK, Mohanty D, editors. First Indo-US Workshop on Coal Mine Methane. Dhanbad:CSIR-CIMFR; 2011. p.19-32. [25] Collings R. Abandoned Coal Mine Methane: Estimating Emissions, Resource and Reserves Prior to Development. In: Singh AK, Mohanty D, editors. First Indo-US Workshop on Coal Mine Methane. Dhanbad:CSIR-CIMFR; 2011. p.149-164. [26] Singh AK, Bar S, Singh PK. Evaluation of Coal Mine Methane Potential of coal seams of Ichhapur coal block, Raniganj Coalfield. In: Paul PK, Roy GC, Islam MM, Sinha IN, editors, International Conference on Coal and Energy – Technological Advances and Future Challenges. Shubpur:BESU; 2013. p. 9-18. [27] Prusty BK, Harpalani S, Singh AK. Quantification of Ventilation Air Methane and its utilization potential at Moonidih Underground Coal Mine, India. In: Panigrahi DC, editor. Ninth International Mine Ventilation Congress. New Delhi:Oxford & IBH Publishing; 2009. p.567-577.

[28] CEA. CO2 Baseline Database for the Indian Power Sector. User Guide Version 10.0. Central Electricity Authority. Ministry of Power, Government of India, New Delhi, 2014. [29] Myhre G, Shindell D, Bréon FM, Collins W, Fuglestvedt J, Huang J, Koch D, Lamarque JF, Lee D, Mendoza B, Nakajima T. Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change Climate change. 2013. p. 731.