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.International Journal of Coal Geology 35 1998 283310

Status of worldwide coal mine methane emissionsand use

Carol J. Bibler ), James S. Marshall, Raymond C. Pilcher

Raen Ridge Resources Incorporated, 584 25 Road, Grand Junction, CO 81505, USA

Received 10 January 1997; revised 27 June 1997; accepted 27 June 1997

Abstract

Underground coal mines worldwide liberate an estimated 2941=109 m3 of methane

annually, of which less than 2.3=109 m3 are used as fuel. The remaining methane is emitted to

the atmosphere, representing the loss of a valuable energy resource. Methane is also a major

greenhouse gas and is thus detrimental to the environment when vented to the atmosphere. Coalmine methane recovery and use represents a cost-effective means of significantly reducing

methane emissions from coal mining, while increasing mine safety and improving mine eco-

nomics. The worlds ten largest coal producers are responsible for 90% of global methane

emissions associated with the coal fuel cycle. China is the largest emitter of coal mine methane,followed by the Commonwealth of Independent States, or CIS particularly Russia, Ukraine and

.Kazakhstan , the United States, Poland, Germany, South Africa, the United Kingdom, Australia,

India and the Czech Republic. Most of these countries use a portion of the methane that is

liberated from their coal mines, but the utilization rate tends to be low and some countries use

none at all. Coal mine methane is currently used for a variety of purposes. Methane is used for

heating and cooking at many mine facilities and nearby residences. It is also used to fuel boilers,to generate electricity, directly heat air for mine ventilation systems and for coal drying. Several

mines in the United States sell high-quality mine gas to natural gas distributors. There are several

barriers to decreasing methane emissions by increasing coal mine methane use. Many of the same

barriers are common to a number of the subject countries. Technical barriers include low-permea-

bility coals, variable or low gas quality, variations in gas supply and demand and lack of

infrastructure. Economic and institutional barriers include lack of information pertinent to

development of the resource, lack of capital and low natural gas prices. A possible option for

)

Corresponding author. Tel.: q1-970-2454088; fax: q1-970-2452514; e-mail [email protected].

0166-5162r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. .PII S 0 1 6 6 - 5 1 6 2 9 8 0 0 0 3 8 - 4

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( )C.J. Bibler et al.rInternational Journal of Coal Geology 35 1998 283 310284

encouraging coal mine methane recovery and use would be international adoption of a tradeable

permit system for methane emissions. q1998 Elsevier Science B.V.

Keywords: coalbed methane; global warming; coal mining; natural gas

1. Introduction

In recent years, coalbed methane has gained attention as a saleable natural gas

resource. Methane can be extracted either from coal seams which will never undergo

mining, or it can be produced as a part of the coal mining process. This paper focuses onmethane which is produced in conjunction with coal mining operations coal mine

. methane . According to the United States Environmental Protection Agency USEPA,. 9 31994a , underground coal mines liberate an estimated 29 to 41=10 m of methane

annually, of which less than 2.3=109 m3 are used as fuel. The remaining methane is

vented to the atmosphere, representing the loss of a valuable energy resource. This paperexamines the potential for recovering and using the methane which is currently being

emitted from coal mines.

There are three primary reasons for recovering coal mine methane. The first reason is

to increase mine safety. Worldwide, there have been thousands of recorded fatalities

from underground mine explosions in which methane was a contributing factor. Using

methane drainage systems, mines can reduce the methane concentration in their ventila-

tion air, ultimately reducing ventilation requirements.

The second reason is to improve mine economics. By reducing emissions and

preventing explosions and outbursts, methane drainage systems can cost effectivelyreduce the amount of time that the coal mine must curtail production. Moreover,

recovered methane can be used either as fuel at the mine site or sold to other users.

The third reason for coalbed methane recovery and use is that it benefits the global

and local environment. Methane is a major greenhouse gas and is second in global

impact only to carbon dioxide; methane thus is detrimental to the environment if vented

to the atmosphere. Although the amount of carbon dioxide accumulating in the atmo-

sphere each year is orders of magnitude larger than that of methane, each additional

gram of methane released to the atmosphere is as much as 22 times more effective in

potentially warming the Earths surface over a 100-year period than each additional .gram of carbon dioxide USEPA, 1994a . Compared with other greenhouse gases,

methane has a relatively short atmospheric lifetime. The lifetime of methane defined as.its atmospheric content divided by its rate of removal is approximately 10 years. Due to

its short lifetime, stabilizing methane emissions can have a dramatic impact on decreas-

ing the buildup of greenhouse gases in the atmosphere.

Coal mine methane recovery and use represent a cost-effective means of significantly

reducing methane emissions from coal mines. Methane, moreover, is a remarkably clean

fuel. Methane combustion produces no sulfur dioxide or particulates and only half the

amount of carbon dioxide that is associated with coal combustion on an energyequivalent basis.

Because of the environmental impact of coal mine methane emissions, the USEPA, .the International Energy Agencys Coal Advisory Board CIAB , and others have

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( )C.J. Bibler et al.rInternational Journal of Coal Geology 35 1998 283 310 285

Table 1a 9 3.Estimated 1990 coal fuel cycle methane emissions from the ten largest coal producing countries 10 m

Country United States EPA Coal industry advisory . .best estimate USEPA, 1994a board estimate IEA, 1994

China 14.024.4 11.3

Former Soviet Union 7.18.8 7.4United States 5.38.4 5.3

Germany 1.51.8 1.8

South Africa 1.23.4 1.3

United Kingdom 0.91.3 1.3

Poland 0.82.2 2.1

Australia 0.71.2 0.7

India 0.6 0.7

Former Czechoslovakia 0.40.7 0.4

Total 31.952.8 32.3

aCIAB estimates do not include emissions associated with coal combustion.

.investigated methane emissions from coal mining worldwide. The USEPA 1994aestimates that the coal fuel cycle which includes coal mining, post-mining coal

. 9 3transportation and handling, and coal combustion emits 35 to 59=10 m of methane

to the atmosphere annually. Table 1 shows methane emissions from the worlds ten

largest coal producers, which are responsible for 90% of global methane emissions

associated with the coal fuel cycle. Underground coal mining is the primary source of

these emissions, accounting for 70 to 95% of total emissions.There are many opportunities for decreasing coal mine methane emissions by

increasing recovery of this abundant fuel. Section 2 examines the status of methane

recovery and use in key countries worldwide.

2. Coal mine methane recovery and use in selected countries

2.1. China

. 9The Peoples Republic of China China produces about 1.2=10 raw tons of hard .coal annually EIA, 1996 . In 1990, coal mining activities in China emitted an estimated

9 3 6 .14 to 24=10 m 10 to 16=10 ton of methane to the atmosphere, contributing

one-third of the worlds total from this source. Not only is China the largest coal

producer in the world; it is unique in that underground mines produce over 95% of the

nations coal. Because of the great depth and high rank of Chinas coals, underground

coal mines have higher methane emissions than surface mines. . .There are currently 108 Coal Mining Administrations CMAs in China Fig. 1 ,

which manage more than 650 mines. These state-owned mines are responsible for mostof Chinas methane emissions, but there are numerous gassy local, township, and private

mines that cumulatively produce over one-half of Chinas coal. However, these non-state .owned mines are not gassy International Energy Agency or IEA, 1994 .

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Fig. 1. The four coal regions in China, with locations of coal mining administrations, selected local mining

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Table 2

Methane emissions from key state-run underground coal mines in China, 1994

6 3 .Region No. of mines Volume of methane in 10 m Coalas depicted productiontotal with vented drained total drained emitted to

6. .in Fig. 1 10 tondrainage liberated and used atmosphere

North 255 53 1,966.1 175.8 2,141.9 135.4 2,006.4 246.8South 217 56 1,530.2 225.2 1,755.5 133.0 1,622.4 89.4

Northeast 168 20 1,114.2 157.3 1,271.4 126.7 1,114.6 93.4

Northwest 29 2 51.7 3.0 54.8 0.0 54.8 8.6

Total 669 131 4,662.2 561.3 5,223.6 395.1 4,798.2 438.2

Source: USEPA, 1996a.

2.1.1. Methane reco

ery and use in ChinaChina has a long history of coal mine methane drainage, and the volume of methane

drained has increased markedly during the past decade. Nationwide, coal mine methane

drainage at state-run mines nearly doubled in 14 years, increasing from 294=106 m3 in6 3 .1980 to more than 561=10 m in 1994 Table 2 . However, this is still less than 11%

of the total methane liberated annually. Approximately 131 state-owned mines currently

have methane drainage systems. Less than one-half of these mines are set up to

distribute and use recovered methane. Chinas state-run coal mining administrations use .about 70% of the methane they drain USEPA, 1996a .

Most of the methane recovered from Chinese mines is used for heating and cookingat mine facilities and nearby residences. Methane is also used for industrial purposes, in

the glass and plastics industries, and as a feedstock for the production of carbon black .an amorphous form of carbon used in pigments and printers ink . Methane is also

being used, to a lesser extent, for power generation. In 1990, the Laohutai Mine at the

Fushun Coal Mining Administration built a 1200 kW methane-fired power station, the

first in China.

Several barriers currently prevent China from developing economic methane recovery

from coal mining to its full potential. Critical barriers include the lack of an appropriate

policy framework, limited capital for project investments and equipment, the need for

additional information and experience with technologies and the lack of a widespread

pipeline network. Artificially regulated low gas prices and difficulty with repatriation of

profits, create barriers to foreign investment in joint ventures for production of domestic .energy resources USEPA, 1993 .

2.1.2. The future of methane deelopment in China

Recognizing the need for a unified effort in advancing coalbed methane development,

Chinas highest governing body, the State Council, established the China United

.Coalbed Methane Company China CBM in May 1996. As a single, trans-sectoralagency, China CBM is responsible for developing the coalbed methane industry by

commercializing the exploration, development, marketing, transportation and utilization

of coalbed methane. The State Council has also granted China CBM exclusive rights to

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undertake the exploration, development and production of coalbed methane in coopera- .tion with foreign partners China Energy Report, 1996 .

More than 20 coalbed methane projects are underway or planned in China, and at

least half of them are taking place at active mining areas. Some of the projects are

state-sponsored, while others involve joint ventures with foreign companies. The future

of the coalbed methane industry in China appears bright. The government recognizescoalbed methanes potential for meeting the nations burgeoning energy needs and is

generally supportive of efforts to develop this resource. With deregulation of energy

prices, increased capital investment in pipeline infrastructure, and ongoing research

efforts, China can likely overcome its remaining barriers to widespread coalbed methane

use.

2.2. Russia, Ukraine and Kazakhstan

In 1994, Russia produced more than 169=106 ton of hard coal, Kazakhstan

produced nearly 104=106 ton and Ukraine more than 90=106 ton. The coal mining

regions of these republics liberate approximately 5.3=109 m3 of methane annually .Table 3 , of which less than 3% is utilized. This amount represents about 20% of world

methane emissions from underground coal mining.

The energy sectors of these Republics are at a turning point. The coal mining

industry, in particular, is undergoing restructuring, a process which includes decreasing

or eliminating subsidies, and closing many of the most unprofitable mines. The industry

is being compelled to become more efficient in order to increase profitability. Miningregions are also seeking to mitigate environmental problems resulting from producing

Table 3

Comparison of characteristics of selected CIS coal basins

Kuznetsk Donetsk Lvov-Volyn Karaganda Pechora

6 a b,g b,g b .Hard coal production 10 ton 58 98 5 103 NrA9 c c c .

Hard coal reserves at active mines 10 ton 10.0 11.6 0.2 NrA NrAa d bNo. of active mines 76 274 18 NrA NrAc e b f f No. of mines draining methane 32 87 4 24 10

9 3 a e c e .Annual methane liberated 10 m 1.1 2.9 0.2 1.1 NrA6 3 a e c e e .Annual methane drained 10 m 196 400 6 182 206

6 3 a e b e e .Annual methane used 10 m 0 70 0 65 102

a .1994 data EIA, 1996; USEPA, 1996b .b .1995 data Saprykin et al., 1995; EIA, 1996 .c .1991 data USEPA, 1994a .d .1996 data written correspondence from Valentin Tchoukhalyov of Partners in Economic Reform PIER in

.Donetsk, Ukraine .e .1993 data Saprykin et al., 1995; Serov, 1995 .f .1989 data Serov, 1995 .g

Coal production in the Donetsk and Lvov-Volyn Basins is estimated based on total 1995 hard coal

production in Ukraine, and 1991 coal production from mines in the Russian portion of the Donetsk Basin.

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Fig. 2. Major coal basins of Russia, Ukraine and Kazakhstan after USEPA

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and using coal. Thus, there is an impetus to utilize more natural gas and decrease

dependency on low grade coal. Increasing recovery and use of coalbed methane is a

potential means of improving mine safety and profitability while meeting the regions

energy and environmental goals.

There are five coal basins in the Commonwealth of Independent States where hard

.coal is mined and which have the potential for coalbed methane development Fig. 2 . . .They are: 1 the Donetsk Basin Donbass , located in southeastern Ukraine and western

. . Russia, 2 the Kuznetsk Basin Kuzbass , located in western Siberia south-central. .Russia , 3 the Lvov-Volyn Basin, located in western Ukraine, which is the southeast-

.ern extension of Polands Lublin Basin, 4 the Pechora Basin, located in northern .Russia and 5 the Karaganda Coal Basin, located in Kazakhstan.

Of the five basins, the Donetsk and Kuznetsk Basins appear to have the largest .near-term potential for coalbed methane development USEPA, 1994b . Both of these

regions are heavily industrialized and present many opportunities for coalbed methane

use. Table 3 compares methane emission and use in these five basins.

2.2.1. Options for methane use in the CIS

2.2.1.1. Heating mine facilities. Currently, most mines use coal-fired boilers to produce

steam heat for drying coal, heating mine facilities and heating ventilation air. In some

cases, mine boilers also supply thermal energy to the surrounding communities. Boilers

can be retrofitted to co-fire methane with coal, a relatively simple and low-cost

procedure. More than 20 mines in the Donetsk and Pechora Basins use methane to fuel

boilers and several mines also use it for directly heating air for the mines ventilation .systems and for coal drying Serov, 1995; Saprykin et al., 1995 .

2.2.1.2. Use in furnaces in the metallurgical industry. Another viable market for

methane use is the metallurgical industry. For example, the city of Novokuznetsk, in the

southern portion of the Kuznetsk Basin, contains numerous gassy mines and is one of

the biggest centers of metallurgy in Russia. The regions metallurgical industry con-

sumes about 54 PJ of natural gas annually, which is equivalent to about 1.4=109 m3 of .methane USEPA, 1996b .

2.2.1.3. Power generation at mine facilities. Most mines purchase electricity from the

power grid. Co-firing coalbed methane with coal to generate electricity on-site may be a

more economical option for these mines. Coalbed methane can be used, independently

of or in conjunction with coal, to generate electricity using boilers, gas turbines and .thermal combustion engines USEPA, 1994b .

2.2.1.4. Use as a motor ehicle fuel. The Donetskugol Coal Production Association in

Ukraine is draining methane in advance of mining using surface boreholes. The

recovered methane is compressed on-site and used as fuel for the Associations vehiclefleet. The refueling station, which has been operating for more than three years,

produces about 1,000 m3 of compressed gas per day. Based on estimated gas reserves it .is expected to operate for a total of eight years Pudak, 1995 .

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While many mines in the CIS are utilizing their methane resources, the majority are

not. Certain barriers must be overcome before recovery and use of coal mine methane

becomes widespread. These barriers and their potential solutions, are discussed in

greater detail in Section 3 of this paper.

2.3. The United States

There are five major coal producing regions in the United States from which hard .coal is mined and which have the potential for coalbed methane development Fig. 3 .

.They are: 1 the Appalachian Basin, located in Pennsylvania, Ohio, West Virginia, . .eastern Kentucky and Tennessee, 2 the Warrior Basin, located in Alabama, 3 the

.Illinois Basin, located in Illinois, Indiana and western Kentucky, 4 the Southwestern

region, including the Uinta, Piceance, Green River and San Juan Basins located in

.Colorado, Utah and New Mexico and 5 the Western Interior region, including theArkoma Basin of Oklahoma and Arkansas.

Table 4 shows that in 1994, an estimated 4.2=109 m3 of methane were liberated by

underground mining in these regions, of which less than 0.7=109 m3 were used .USEPA, unpublished data .

Currently in the United States, at least 17 mines in six states Alabama, Colorado,.Ohio, Pennsylvania, Virginia and West Virginia recover methane for profit, primarily

through sale to gas distributors. In 1995, the total methane recovered from these mines,

including vertical wells draining methane in advance of mining, exceeded 1=109 m3.

By maximizing the amount of gas recovered via drainage systems, these mines havegreatly reduced their ventilation costs, improved safety conditions for miners and have

collected and sold large quantities of high-quality gas. Following is a brief description of

selected coal mine methane recovery activities in the United States.

2.3.1. Warrior basin: Alabama

Six of the seventeen US mines with commercial methane recovery systems are

located in the Warrior Basin of Alabama. Today, energy companies recover methane .from the Warrior Basin by horizontal wells, gob wells in areas being mined and

.vertical wells in both mined and unmined areas . Most of this gas is sold to regionalnatural gas distributors, although there is some on-site mine use. In 1995, four mines

operated by Jim Walter Resources produced more than 380=10 6 m3 of methane for

pipeline sale and USXs Oak Grove Mine recovered an estimated 117=10 6 m3 of

methane for use.

2.3.2. Appalachian region

Eight mines in Virginia and West Virginia have developed successful methane

recovery and use projects. The Consol mines in Virginia are the most well-documented

examples. Consol produces gas from a combination of vertical wells that are hydrauli-cally stimulated, horizontal boreholes and gob wells drilled over longwall panels. In

1995, Consol produced approximately 688=10 6 m3 of saleable methane from three

mines. Methane recovery efficiency at these mines is higher than 60%.

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Fig. 3. Principal coal-bearing basins of the US and estimates of in-place coalbed methane resou

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Table 4 6 3.Estimated 1994 methane emissions from underground mines in the United States 10 m

a .Region as depicted in Fig. 3 Total liberated during mining Drained and used Emitted to atmosphere

Appalachian Basin 2,337.6 313.3 2,024.3

Warrior Basin 1,245.7 351.0 894.7

Illinois Basin 334.8 0 334.8bSouthwestern region basins 261.3 0.4 260.9

Western Interior basins 1.0 0 1.0

Total 4,180.4 664.7 3,515.7

aThis figure does not include methane produced by vertical wells draining methane in advance of mining. In

1994, the Appalachian Basin produced about 337.4 million m 3 of saleable methane from vertical wells in

advance of mining.b

Includes the Uinta, Piceance, San Juan and Raton Basins. .Source: USEPA, unpublished data compiled for draft report in progress on United States methane emissions

estimates.

2.3.3. Southwestern region

The Soldier Canyon Mine in Utah recovered about 10.9=10 6 m3 of methane for

sale annually until early 1994, when production was curtailed and gas sales ended due to

low market prices.

2.3.4. Summary

While methane recovery has been economically implemented at the above-described

mines, safety and high coal productivity remain the impetus for their degasification

efforts. Methane drainage at many gassy mines in the United States is limited ornonexistent. Section 3 of this paper discusses potential avenues for increasing methane

recovery and use in the United States and other countries.

2.4. Germany

Germany produced nearly 54 million tons of hard coal in 1995, all from underground .mines Schiffer, 1995 . Of this total, 43 million tons were mined from the Ruhr Basin in

.northwestern Germany Von Sperber et al., 1996 and most of the remainder was mined .from the Saar Basin in southwestern Germany Fig. 4 . Until recently, hard coal mining

was heavily subsidized in Germany, and the industrys future is in question Schiffer,.1995 . Even mines that are closed, however, can continue to liberate methane for long

periods of time. An estimated 1.8=109 m3 of methane are liberated annually from

underground mining activities in Germany, of which 520=10 6 m3, or 30%, are drained . 6 3IEA, 1994 . About 371=10 m , or 71% of all drained methane, is used, primarily for

heating or power generation.

Government officials suggest that as much as 45% of the methane emitted from coal

mining activities could be drained and used in a variety of applications. The primary

barrier to increased methane recovery is low methane concentrations in the gas mixture.

Safety regulations in Germany prohibit any utilization if the methane content is less than25%. If the average recovery efficiency at German mines is to be increased, it will be

necessary to adopt practices that will recover methane in a more concentrated form.

These measures are discussed further in Section 3.

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.Fig. 4. Principal coal-bearing basins of Germany after IEA, 1994 .

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2.5. South Africa

South Africas major coal operations are centered in the northern Karoo Basin in the .Transvaal and Natal regions of the eastern part of the country Fig. 5 . More than 98

million tons of hard coal were produced from underground mines in 1994 Walker,

.1995 . Underground mining is expanding as surface mineable resources become lesswidely available.

.Fig. 5. Principal coal-bearing basins of South Africa after IEA, 1994 .

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An estimated 1.1=106 m3 of methane is liberated by underground mining activities .in South Africa annually IEA, 1994 . No information on methane drainage is available,

and while underground horizontal drilling is done in some mines, the primary purpose is

exploration and not methane recovery. None of the recovered methane is utilized. South

African coals are considered to have relatively high permeability, and IEA estimates that

recovery efficiencies of 25 to 35% could be supported. South African mines have arecord of disastrous methane outbursts, including three major disasters in the 1980s.

Increasing methane recovery could avert future disasters and increase coal output, whileat the same time producing valuable gas for sale or use Industrial and Petrochemical

.Consultants Ltd., 1991 .

2.6. United Kingdom

. 6Coal is mined throughout the UK Fig. 6 which produced 43=10 ton of coal from

.

9 3

underground mines in 1994 World Coal, 1995 . About 1.1 to 1.3=

10 m of methaneare liberated from underground mining annually, of which nearly 0.4=109 m3 are9 3 .drained and 0.1 to 0.2=10 m are used IEA, 1994; USEPA, 1994a .

Large-scale drainage and utilization of coal mine methane began in Britain in the .1950s at the Point of Ayr Colliery in North Wales Young et al., 1994 . By the

mid-1960s, mine gas utilization in Britain was well established at numerous mines.

Recovered methane was used primarily to generate steam for mine facilities, but coal

mine gas was also sold to domestic and industrial users as town gas. In 1977, the Point

of Ayr Colliery brought a gas turbine system on line to generate electricity from

recovered methane and the 1.3 MW system used about half of the mine gas produced toprovide 30% of the collierys electricity needs. The most recent advances in mine gas

utilization have been at the Harworth Colliery in Nottinghamshire, where a 15 MW gas

turbine electricity generator, fueled entirely by mine methane, has been brought on line.

This is the largest turbine fueled by coal-mine methane in Europe.

Increased recovery and use of mine methane in the United Kingdom has been

restricted by the relatively low permeability of the coal, low gas pressures and the

resulting difficulty in using horizontal in-seam boreholes to recover methane. Further-

more, vertical holes for draining methane from the surface in advance of mining have

not been drilled due to concerns over the effects of hydraulic stimulation on mining,

drilling costs, the potential disturbance of aquifers and environmental objections to .multiple surface facilities and pipelines IEA, 1994 . If these barriers can be overcome,

methane recovery from United Kingdom mines could be increased.

2.7. Poland and the Czech Republic

.About three-fourths of the Upper Silesian Coal Basin USCB lies in southern Poland . .Fig. 7 and the remaining one-fourth is in the northeastern Czech Republic Fig. 8 ,

.where it is known as the Ostrava-Karvina Coal Basin OKR . The USCB accounts for

about 97% of all hard coal production and more than 98% of underground coal minemethane emissions in Poland and the Czech Republic. Therefore, this paper will not

discuss the much smaller hard-coal producing basins of the region, such as the Lower

Silesian Coal Basin and Central Bohemian Coal Basins.

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.Fig. 6. Principal coal-bearing basins of the United Kingdom after IEA, 1994 .

Both Poland and the Czech Republic began actively draining methane, for safety

reasons, in the late 1950s. About 18 of the 62 mines in the Polish portion of the USCBand all ten in the Czech portion, have methane drainage systems USEPA, 1995a;

.USEPA, 1992 . Methane is drained simultaneously with coal extraction at the working

face, from gob areas and from development areas. Underground mining in the USCB

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.Fig. 8. Principal coal-bearing basins of the Czech Republic after USEPA, 1992 .

2.8. Australia

Australia produces coal primarily from the eastern portion of the continent in .Queensland, New South Wales and Victoria Fig. 9 . Total coal reserves are estimated at

Table 5Methane liberation data, Upper Silesian Coal Basin, Poland and the Czech Republic. 1993 data except where

.otherwise noted

Poland Czech Republic Total

2 .Basin area km 5,800 1,600 7,400aActive mining concessions in 1996 62 10 72

6 .Hard coal production 10 ton 16.3 127.2 143.56 3 .Methane liberated by mining 10 m 753.5 355.8 1,109.3

6 3 .Methane drained 10 m 212.8 117.9 330.76 3

.Methane used 10 m 167.7 105.3 273.06 3 .Methane emitted to atmosphere 10 m 585.8 250.5 836.3

aEstimated based on 1992 data.

Sources: USEPA, 1995a; Takla et al., 1995.

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.Fig. 9. Principal coal-bearing basins of Australia after IEA, 1994 .

9 . 6nearly 325=10 ton IEA, 1994 . About 53=10 ton of coal are produced from

underground mines annually. In 1990, Australias underground mines liberated an

estimated 594 to 1,162=10 6 m3 of methane, of which 70 to 122=106 m3 were used .IEA, 1994; USEPA, 1994a , primarily for electricity generation.

A new power generation project was completed in 1996 and managed by the Appin

Power Partnership. The project is scheduled to use at least 155 million m 3 of coal mine

methane annually, supplied by BHPs Appin and Tower collieries, to generate electricity

using state-of-the art lean-burn gas engine technology. A total of 94, 1 MW gas engines

are operating at the two collieries, 54 of them at Appin and 40 at Tower. In addition,Appin uses 65 m3rsecond of ventilation air to produce between 4 and 8 MW of

electricity, depending on the methane content of the ventilation air. Use of mine

ventilation air increases the overall output of the power plant by 7 to nearly 15%. Tower

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Colliery is currently unable to utilize its ventilation air, however, as the exhaust shaft

nearest to the power generation facility is scheduled to be converted to an intake shaft .Hammonds, 1996, written communication .

The power generated at Appin and Tower Collieries is sold and distributed locally for

use in about 60,000 homes. In addition to reducing Australias coal mine methane

emissions, the project has created 30 new jobs and improved the reliability of the localpower supply. With continued success, this project should serve as a model for methane

use at gassy underground coal mines worldwide.

.Fig. 10. Principal coal-bearing basins of India after IEA, 1994 .

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2.9. India

The largest coalfields in India are located in the eastern and central states of Bihar,

West Bengal and Madhya Pradesh, but other resources are scattered throughout the .country Fig. 10 . Most of Indias coal is produced from surface mines, but its 355

6 .underground mines produce nearly 64=10 ton of coal annually Wilcox, 1995 . . .Mitra 1992 reported that only a small portion 3.5 million tons annually of Indias

underground-mined coal is produced from gassy mines, and that these mines liberate an3 .average of 20 m of methane per ton of coal mined. IEA 1994 estimates that

underground mining in India liberates 576=10 6 m3 of methane annually, a relatively

small amount compared to other countries examined in this paper. However, government

reforms and industrialization are contributing to rapid increases in coal demand, which

may cause underground coal production to increase in the future. Therefore, methane

emissions from underground mining may also increase.

Coal mine methane drainage attempts in India have been limited, and no knowndrainage programs are in place. Serious mine methane explosions have occurred,

however, and many lives have been lost. Implementation of methane drainage programs

at Indias gassy mines would clearly be desirable from the standpoint of safety and mine .productivity. IEA 1994 estimates that India could recover 25 to 35% of the methane it

currently emits. The market potential for this methane will be strong, given Indias

growing need for domestic energy sources.

3. Barriers to decreasing coal mine methane emissions

There are several barriers to decreasing methane emissions by increasing coal mine

methane use. Some are technical, such as low coal permeability, while other are

institutional, such as low gas prices. In a few cases, certain barriers are country- or

region-specific, but most cases, many of the same barriers exist in a number of

countries. This section discusses obstacles to increased coal mine methane use, and

potential ways to overcome these obstacles.

3.1. Technical issues

3.1.1. Low-permeability coals

Coal seams that exhibit low permeability pose special problems for developing

successful methane drainage and recovery systems. Methane desorbs and flows through

natural pores and fractures until the gas reaches the mine face or borehole. Stimulation

technology that enhances the flow of gases from the seam into a recovery system has

been successfully used in the past several years. Early efforts to modify fracturing .techniques for application in coal seams were largely unsuccessful IEA, 1994 . The

current practice of hydraulic stimulation in coals, however, minimizes roof damagewhile achieving extensive fracturing. Under ideal conditions, 60 to 70% of the methane

contained in the coal seam can be removed using vertical degasification wells drilled .more than 10 years in advance of mining assuming a permeability of at least 1 10 md .

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These efforts have been successful in the United States and other industrialized

countries. Transfer of this technology to other countries can help increase coal mine

methane recovery.

3.1.2. Variable or low gas quality

Often, the gas drained during mining contains low concentrations of methane,sometimes as low as 30%. In some countries, use of gas at concentrations of less than

25% is prohibited. Clearly, it is desirable to produce the highest quality gas possible and .to ensure that quality concentration variations are minimized. In the short term, there

are several relatively inexpensive, low-technology methods of improving the quality of .recovered mine gas in many countries. These include shutting in old wells in-mine ,

.reducing leaks in the in-mine and surface gas gathering systems pipelines and

improving grouting of standpipes. In the long term, there are several methods for

improving gas quality which require some investment and higher technology than some

mines currently have.There are three primary means of improving the quality of gas recovered from coal

.mines USEPA, 1995a . The first of these is improved monitoring and control. One of

the most economical methods to improve the quality of gas is to reduce air entrapment

in the gas stream during the production process. Since the ratio of methane liberated

generally declines with time, it is necessary to adjust critical production parameters

frequently in order to control the pressure and maintain a high methane concentration in

the product gas. Continuous monitoring of the oxygen content at the wellhead, adjusting

the production rate and monitoring the mine ventilation system can all help improve gas

quality.Second, gas quality can be improved by increasing pre-mine drainage. Gas drained in

advance of mining usually has a higher methane content than that drained from working

faces or gob areas. Advanced pre-mine drainage techniques include use of vertical wells

drilled from the surface and use of more numerous and more strategically placed,

cross-measure boreholes drilled in advance of mining.

Third, gas quality can be improved by enriching gas through removal of one or more

of the following contaminants: nitrogen, oxygen, carbon dioxide and moisture. Cryo-

genic processes for separating nitrogen and air from methane have been successful for

large-scale conventional natural gas operations, but most require high capital investment 3 .and are economically viable only for very large gas flows millions of m per day .

There are a number of enrichment processes currently being evaluated for use at

small-scale operations, including a pressure swing adsorption process that was tested at .the Buchanan Mine in the United States Shirley et al., 1997 .

3.1.3. Variations in gas supply and demand

Many mines that currently use methane for heating purposes face a shortage of gas

during the winter months when demand is high, yet vent large quantities to the

atmosphere during summer months when demand is low. Fluctuations in methane supplydue to seasonal or market demand are a common barrier to implementing or expanding

methane use projects. This barrier can be overcome by developing or expanding gas

storage capacity. In many gas producing areas of the world, underground storage is the

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most common means of storing gas to meet peak seasonal market requirements. The

most commonly used storage sites are porous reservoirs, including depleted oil and gas

fields, as well as aqueous reservoirs.

In China, the primary means of coalbed methane storage is surface storage tanks .using the Higgins floating lid design Fig. 11 . Coalbed methane drained from under-

ground mines is transported to the storage tanks, and then supplied to nearby houses,schools and other consumers via pressure adjustment stations and pipelines. The

largest-capacity surface storage tank is only 10,000 m3, however, which is much less

than most subsurface reservoirs.

In addition to conventional storage facilities, another available option is gas storage

in abandoned coal mines or shafts. Since the early 1980s, two abandoned mines in .Belgium have stored imported natural gas Moerman, 1982 . In Poland, coalbed methane

Fig. 11. 10,000 m3-capacity Higgins floating top storage tank at the Kailuan Coal Mining Administration,

China.

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.is being stored in an inactive shaft at the gassy Morcinek Mine Gatnar, 1994 . The

storage facility, developed in 1994, has a capacity of 35,000 m3. Methane drained from

this mine is normally delivered to its preparation plant drying station and its boiler

house. When there is no demand at those facilities, the gas is delivered to the storage

reservoir. When the demand for methane exceeds that which can be supplied by the

drainage station, methane flows from the storage reservoir to the drainage station andthen to the boiler house andror preparation plant.

3.1.4. Lack of infrastructure

Many coal mining areas lack pipelines or gathering systems to collect and transport

gas. In such cases, it is most economical to use coal mine methane locally where

compression and long-distance transportation is unnecessary.

3.2. Economic and institutional issues

In addition to the technical obstacles described above, there are a variety of other

issues that have prevented coal mine methane recovery from becoming more widespread.

These issues include lack of information, lack of capital, low natural gas prices and risks

associated with foreign investment. Each of these issues is explored below.

3.2.1. Lack of information

In the United States and other countries, one of the problems that has slowed coal

mine methane project development is that some coal mine operators do not have

adequate information regarding coal mine methane projects. While much has beenpublished on the subject, methane recovery is still seen as a relatively new concept to

many coal operators. A related constraint is that some coal operators simply do not have

the time or resources to investigate the potential to develop a profitable project at their

own coal mine.

The key strategy for overcoming informational barriers in the United States has been

to develop outreach programs. Outreach programs work well when companies are shown

that they can profit while at the same time reducing emissions or improving mine safety.

Examples of outreach programs include the USEPAs Coalbed Methane Outreach

Program, which is conducted in the United States, and the Coalbed Methane Clearing-houses in Poland, China and Russia. These institutions distribute information and link

together interested parties, provide technical training, and in some cases perform

pre-feasibility assessments for specific projects.

3.2.2. Lack of capital

Even when a pre-feasibility assessment has demonstrated that the economics of a coal

mine methane project are attractive, a lack of financing may prevent projects from

taking place. Coal companies often do not have surplus capital available to invest in

coalbed methane recovery and use projects because available capital must be invested intheir primary business of coal production. Additionally, some lending organizations may

be unfamiliar with the relatively new concept of coal mine methane recovery and use,

and project developers may thus be unable to secure the necessary up-front financing

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needed to cover the large capital investments required for such projects. Following are

two types of solutions to this obstacle that are currently available or could readily be

implemented in some countries; a third, the concept of tradeable permits, is discussed

separately in Section 3.3.

3.2.2.1. Tax incenties. Governments can use a variety of different tax incentives to spurdevelopment. Coal mine methane projects may qualify for tax incentives that have been

developed for certain types of environmental, energy, and economic development

projects. One type of incentive is tax exemptions, which exclude an item or activity

from the base upon which tax is computed. Poland, for example, grants an unusually

generous 10 yr corporate tax exemption to entities engaged in oil, gas, and coal mine

methane prospecting. Tax credits, another form of incentive, reduce the overall tax

liability of a project, thereby increasing profitability. Depending on the size of the credit,

tax credits can have a very large impact on encouraging the development of certain

types of projects. For example, the United States coalbed methane industry benefittedgreatly from the Federal Section 29 Tax Credit, which was designed to promote the

development of unconventional energy projects. A third type of incentive is tax

deductions. Tax deductions are frequently associated with business income taxes, and

like exemptions, they reduce the base upon which tax is computed. Unlike tax credits

however, deductions cannot offset the total tax liability for the year and cannot be

carried forward and applied to future tax years.

3.2.2.2. Capital access assistance. This type of assistance provides access to capital

.through grants, loans, loan guarantees and venture capital USEPA, 1995b . Coal minesor joint ventures may be able to use these types of assistance to finance coal mine

methane projects.

3.2.3. Low natural gas prices

In some countries natural gas prices are held at artificially low rates. Even in

countries whose gas prices are at market levels, prices may be low due to low demand.

In such cases, special types of incentives to encourage coal mine methane recovery

could be implemented. For example, legislation could be enacted requiring local

distribution companies to purchase recovered coal mine methane if it is sold at acompetitive price. China has recently established preferential policies for projects which

involve gas recovery and use from coal mines. The government has also passed a law

exempting coalbed methane producers from royalties and land occupation fees for

production of up to 2=109 m3 of methane per year.

3.3. A possible option for encouraging coal mine methane recoery and use: The

tradeable permit system

Section 2 of this paper mentions several profitable examples of mine methane use

worldwide. For the most part, however, large-scale coal mine methane recovery and use

projects are undertaken only by large, well-funded coal companies. In general, mining

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companies have implemented degasification projects in situations where safety and mine

productivity necessitate them. On-site utilization andror sale of the recovered methane

has been secondary and while it has been profitable in certain instances, it is has not

proven highly lucrative. Despite the various solutions described above to overcoming

capital constraints associated with implementing methane recovery programs, most

mining companies, especially the smaller ones, do not have a sufficient incentive to doso.

At the United Nations Conference on Environment and Development in Rio de

Janeiro in June, 1992, 155 countries signed a Framework Convention on Climate

Change whose goal is to stabilize atmospheric greenhouse gas concentrations, including .methane, at a level that does not interfere with the climate system UNCTAD, 1995 .

The convention came into force in March 1994. The means chosen to implement the

convention have not yet been determined. Among the possibilities under consideration

are emissions taxes, external offsets and tradeable permits.

Emissions taxes would be inherently punitive and probably difficult to enforce,especially on an international scale. External offsets would allow countries to meet their

targets by financing emission reductions in other countries where reductions can be

achieved more easily or more cheaply, or both. One objection to this approach is that the

wealthy countries would, in the process, increase their ownership of assets in the poorer

countries, a situation which poorer countries could find objectionable.

The third option, tradeable permits, involves defining an overall emissions reduction

target for all participating countries. Individual countries would then be issued permits to

emit carbon to a certain level. The sum of these permits would equal the overall target.

Participants would have to hold permits equal to the value of their emissions. If theyproved insufficient, they would have to buy or lease permits from other participants

which had permits in excess of their requirements.

There are a number of precedents from which valuable insights can be gained about

how such as system might work. One is the tradeable emission permit system first

introduced by the USEPA during the 1970s. The USEPAs Emissions Trading Program

allowed polluters to reduce their emissions below a set standard and then apply for a

credit which could be used to offset excess emissions at other places. The USEPA

allowed these credits to become transferable and tradeable. This concept has been

applied in several ways in the United States and other countries and its versatility hasbeen proven. One example from the United States involved the introduction of lead-free

gasoline. A permit program was introduced which allowed gasoline refiners that reduced

lead levels below those required in one quarter of the year to bank credits for subsequent

quarters. The credits could also be transferred from one refiner to another. Refiners that

could not immediately meet the required levels were saved from the expense of legal

action by buying credits to give them time to comply.

Another example is the control of acid rain precursors in the United States. Reducing

discharge of sulfur dioxide by imposing emissions fines would have been prohibitively

expensive. Instead, companies who reduced emissions below established levels receiveda credit. A market quickly developed for sulfur dioxide allowances. As a result, scrubber

technology has improved and many companies are actually over-complying with emis-

sions regulations.

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Coal mine methane emissions reduction lends itself to such a program because it

meets the most important prerequisite of a tradeable permit commodity-the emissions

can be measured from the source. If mines could receive a credit for the greenhouse gas

reduction value of their methane, it could become a significant source of revenue for the

mines. There are many ways that the system could work, but it would likely center on a

pre-determined emissions level. For example, if it was determined that underground coalmines had to ensure that methane emissions were kept at 1990 levels, then mines whose

emissions were less than that level could sell their excess permits into the market. Mines

would thus have an incentive to reduce their emissions by utilizing the methane.

4. Conclusions

As discussed above, coal mines worldwide emit large volumes of methane, much of

which could be recovered and used as fuel. In many instances, countries whose minesemit large quantities of methane are in critical need of a domestic energy source,

particularly one which is clean-burning. In countries whose economies are in transition,

such as China, the former Soviet Union and the Eastern European nations, coal mine

methane recovery offers economic benefits as a new industry that can help provide jobs

for displaced coal miners or other workers. In countries whose economies are estab-

lished, such as the United States, the United Kingdom and Australia, coal mine methane

recovery may help increase the profit margin of mining enterprises.

The reduction of methane emissions can have a significant global impact, but

incentives are needed to encourage more widespread recovery of coal mine methane. Anincentive program offered on an international level would probably be the most effective

means of stimulating development of the coal mine methane industry. Of the various

options for international-level incentives, a system of tradeable permits for methane

emissions would likely be the most cost effective.

Due to various technical, economic and institutional barriers, it will never be possible

to completely eliminate emissions of methane from coal mines. However, a worldwide

coal mine methane utilization rate of 25% may be realizable, particularly if an

international incentive program is implemented. This would reduce the estimated

emissions of coal mine methane to the atmosphere by 7 to 10=109 m3 annually,substantially reducing greenhouse gas emissions and curtailing the waste of a valuable

energy source.

Acknowledgements

The authors wish to thank the United States Environmental Protection Agency .USEPA and the United Nations for giving them the opportunity to work on projects

aimed at reducing methane emissions from coal mines in many of the countriesdiscussed in this paper. The authors are grateful to Pramod Thakur of Consol, and

Romeo Flores of the United States Geological Survey for their valuable insight and

review of this manuscript. The Coalbed Methane Clearinghouses in China, Poland and

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Russia have provided a large amount of background information used in this manuscript.

Dina Kruger of the United States Environmental Protection Agency, Wal Hammonds of

Appin Power Partnership and Mary DePasquale of ICF, also provided assistance.

References

China Energy Report, 1996. State Council launches methane company. China Energy Rept. 3, 7.

Energy Information Administration, 1996. World energy database for the International Energy Annual. US

Dept. of Energy, Energy Infor. Adm. World Wide Web site, http:rrwww.eia.doe.govremeurworld.

Gatnar, K., 1994. The problems of capturing and the optimum utilisation of coalbed methane from mining

concessions of the Jastrzebie Coal Company. In: The Silesian International Conference on Coalbed

Methane Utilisation Proceedings, Katowice, Poland. Polish Foundation for Energy Efficiency, Katowice,

Poland.

International Energy Agency, 1994. Global Methane and the Coal Industry. Int. Ener. Agency Coal Ind.

Advisory Board, Paris, France, 67 pp.Industrial and Petrochemical Consultants Ltd., 1991. Coalbed Methane Resource Development. Natl. Ener.

Council, Pretoria, South Africa, 59 pp. .Mitra, A.P. Ed. , 1992. Global Change: Greenhouse Gas Emission in India. Sci. Rep., vol. 4. India Council of

Scientific and Industrial Research and Ministry of Environment and Forests, 61 pp.

Moerman, A., 1982. Internal Report on Gas Storage in Perrones-Les-Binche. S.A. Distrigaz, 19 pp.

Pudak, V.V., 1995. Degassing of methane bearing geologic structures in the Donbass coal basin by the .Donetsk Coal Association. International Unconventional Natural Gas Symposium Intergas 95 Proceed-

ings. Univ. of Alabama, Tuscaloosa, Alabama, pp. 517529. .Rice, D.D., Law, B.E., Clayton, J.L., 1993. Coalbed gas: An undeveloped resource. In: Howel, D.D. Ed. ,

The Future of Energy Gases. US Geol. Surv., pp. 389404.

Saprykin, V.L, Boxerman, Y.A., Karp, I.N., Pyatnichko, A.I., 1995. Technical and economic feasibility of

coalbed methane production and utilization in the Ukraine. International Unconventional Natural Gas .Symposium Intergas 95 Proceedings. Univ. of Alabama, Tuscaloosa, Alabama, pp. 531540.

Schiffer, H.W., 1995. What Future for German Coal? World Coal, July 1995, pp. 1622.

Serov, V.I., 1995. Economical aspects of coalbed methane extraction and utilization by coal mines in the CIS. .International Unconventional Natural Gas Symposium Intergas 95 Proceedings. Univ. of Alabama,

Tuscaloosa, Alabama, pp. 179183.

Shirley, A., Porto, J., Hawk, E., 1997. A demonstration of methane recovery from coal mine gases by pressure

swing adsorption. 1997 International Coalbed Methane Symposium. Univ. of Alabama, Tuscaloosa,

Alabama, unpublished presentation.

Takla, G., Bezdek, J., Vavrusak, Z., 1995. Coalbed methane recovery in the Czech Republic. International .Unconventional Natural Gas Symposium Intergas 95 Proceedings. Univ. of Alabama, Tuscaloosa,

Alabama, pp. 361368.

United Nations Conference on Trade and Development, 1995. Controlling carbon dioxide emissions: The

tradeable permit system. United Nations Conference on Trade and Development, UNCTADrGIDr11, 39

pp.

United States Environmental Protection Agency, 1991. Assessment of the potential for economic development

and utilization of coalbed methane in Poland. US Env. Protection Agency, EPAr40011-911032.

United States Environmental Protection Agency, 1992. Assessment of the potential for economic development

and utilization of coalbed methane in Czechoslovakia. US Env. Protection Agency, EPA 430-R-92-1008,

76 pp.

United States Environmental Protection Agency, 1993. Options for Reducing Methane Emissions Internation- .ally, vol. II: International Opportunities for Reducing Methane Emissions Report to Congress . US Env.

Protection Agency, EPA 430-R-93-006B.

United States Environmental Protection Agency, 1994a. International Anthropogenic Methane Emissions:

Estimates for 1990. US Env. Protection Agency, EPA 230-R-93-010.

7/31/2019 Science (16)

28/28


United States Environmental Protection Agency, 1994b. Reducing Methane Emissions from Coal Mines in

Russia and Ukraine: The Potential for Coalbed Methane Development. US Env. Protection Agency, EPA

430-K-94-003, 68 pp.

United States Environmental Protection Agency, 1995a. Reducing Methane Emissions from Coal Mines in

Poland: A Handbook for Expanding Coalbed Methane Recovery and Use in the Upper Silesian Coal Basin.

US Env. Protection Agency, EPA 430-R-95-003, 122 pp.

United States Environmental Protection Agency, 1995b. Finance Opportunities for Coal Mine MethaneProjects: A Guide for Southwestern Pennsylvania. US Env. Protection Agency, EPA 430-R-95-008, 70 pp.

United States Environmental Protection Agency, 1996a. Reducing Methane Emissions from Coal Mines in

China: The Potential for Coalbed Methane Development. US Env. Protection Agency, EPA 430-R-96-005.

United States Environmental Protection Agency, 1996b. Reducing Methane Emissions from Coal Mines in

Russia: A Handbook for Expanding Coalbed Methane Recovery and Use in the Kuznetsk Coal Basin. US

Environmental Protection Agency, Washington, DC, EPA 430-D-95-001, 65 pp.

Von Sperber, M., Kunz, E., Juch, D., Gaschnitz, R., 1996. Potential Coalbed Methane Resources and Actual

Exploration Efforts in Ruhr-District, Germany. Coalbed Methane Forum, Morgantown, West Virginia.

November 1921, 2 pp., distributed unpublished report.

Walker, S., 1995. South Africa looks to Better Times. World Coal, Oct. 1995, pp. 3546.

Wilcox, S., 1995. Indian Coal: A Time of Change. World Coal, Sept. 1995, pp. 2029.World Coal, 1995. UK Coal-back to the Future. World Coal, April 1995, pp. 2231.

Young, S.R., Baily, H.E., Holloway, S., Glover, B.W., 1994. The history of mine gas utilisation and status of

coalbed methane development in the UK. The Silesian International Conference on Coalbed Methane

Utilisation Proceedings, Katowice, Poland. Polish Found. for Ener. Efficiency, Katowice, Poland.

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