Post on 03-Mar-2020
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Global CMM and AMM Emissions: Implications of Mining Depth and Future
Coal Production
April 16, 2018, Toronto, Canada
Nazar Kholod1, Meredydd Evans1, Raymond C. Pilcher2, Michael Coté3, Ron Collings3
1 Pacific Northwest National Laboratory; 2 Raven Ridge Resources; 3 Ruby Canyon Engineering
Global Methane Forum
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Introduction: CMM Emissions and Coal Production
▪ Coal mines get deeper every year and methane
emissions grow with increasing mining depth
▪ Data show flat or declining coal production, while
CMM emissions continue to grow
▪ No studies on future AMM estimates
▪ Purpose: estimate global CMM and AMM emissions
from hard underground and surface coal with
increasing mining depth through 2100
▪ This study was born out of discussions on emissions
and mine depth during GMI Coal Subcommittee
meeting
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CMM Methodology
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▪ Use coal production data from the Socioeconomic Pathways (2010-2100)
▪ Split hard coal by underground and surface
▪ Estimate the rate of change in mining depth
▪ Establish emission factors at given depths and for different coal ranks using
measured data
Gas content depend on coal rank and mining depth. Raven Ridge developed the formula using data from over 250 coal samples from North America, South America, Asia and Europe
Estimates of future coal production under various scenarios
0
5
10
15
20
25
30
0 100 200 300 400 500 600 700 800 900 1000
AnthraciteBituminousSubbituminous
Mining depth, meters
m3/t
0
100
200
300
400
500
2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
SSP2-Baseline
SSP2-6.0
SSP2-2.6
EJ/year
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Trends in Global Coal Mining
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▪ The study uses data from key coal producing countries in 1990-2010
▪ The share of underground mining is shrinking because surface mining is more
economical
▪ Depth of underground mines is increasing
▪ Share of brown coal is decreasing
▪ Trends are extended by 2100
0%
10%
20%
30%
40%
50%
60%
70%
80%
2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Share of underground coal in hard coal,%
0
200
400
600
800
1000
1200
2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Depth of underground mines, meters
SSP2-Baseline; Preliminary data
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Ratio of Emissions to Formula-Derived Gas Content
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▪ Based on coal production, emissions and mining depth data from the United
States, the ratio of emissions to gas content is estimated at 1.8
Specific emissions = gas content
0
2
4
6
8
10
12
14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
Mine numbers
Rat
io o
f sp
ecif
ic e
mis
sio
ns
to g
as c
on
ten
t, t
imes
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Global CMM: Reference Scenario
6SSP2-Baseline (average); Ratio 1.8; No utilization. Preliminary data
▪ Share of CMM emissions from underground hard coal in total CMM emissions is 92% in 2010 and 78% in 2100
0
50
100
150
200
250
300
350
400
450
500
2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Met
han
e em
issi
on
s, b
cm
Underground
Surface
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AMM Methodology
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▪ Calculate initial emissions from abandoned mines based on the CMM
methodology
▪ Calculate the global average coal abandonment rate
▪ Make assumption on the decline rates in emissions over time in dry and flooded
mines
▪ Calculate the emissions from the coal mines abandoned in the past (1971-2010)
▪ Calculate future AMM emissions from dry and flooded mines
Coal abandonment rate = Abandoned coal production (capacity) / Total coal production (capacity)
Global abandonment rate = 5% of coal production (capacity) per year 0
20
40
60
80
100
0 5 10 15 20
% o
f in
itia
l em
issi
on
s
Year from abandonment
Dry mines
Flooded mines
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Global AMM Emissions: Reference Scenario
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▪ AMM’s share in total methane from coal is 17% in 2010
▪ This share is projected to increase to 24% in 2050 and 27% in 2100
0
100
200
300
400
500
600
700
2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
CMM
AMM
CM
M a
nd
AM
M e
mis
sio
ns,
bcm
SSP2-Baseline (average); Ratio 1.7; No utilization. Preliminary data
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Importance of AMM: Baseline and Policy Scenarios
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▪ AMM increase faster than underground coal production and CMM
▪ Underground coal by 2.6 times, CMM by 3.5, AMM by 7.8 times
▪ AMM’s share in total emissions increases in policy scenarios
▪ 34% in SSP2-6.0 and 44% in SSP2-2.6 in 2100
CMM emissions follow the trajectory of coal production
AMM emissions continue to grow even if coal production and CMM decline
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Uncertainty
▪ Three most important factors for CMM calculations in 2050
Variable Low High
Future coal production (SSP2 from different models)
-25% +31%
Ratio of emissions to gas content -37% +26%
Future share of underground coal in hard coal production
-15% +16%
Research needs:
▪ Ratio of emissions to gas content
▪ Depth of underground and surface mines
▪ Ratio of dry and flooded mines
▪ Percentage of sealed mines
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Improving Inventories and Emission Factors
▪ Methodology and data used in this study could help
improve future inventories and emission factors
▪ CMM emissions factors by depth and coal rank are
more detailed than current emission factors and may
▪ AMM methodology can help in capturing more
complete emissions, mitigation opportunities
▪ Methodology can also be used to cross-check more
detailed, bottom-up estimates
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Conclusions
▪ Estimates are double those of previous studies
because of the additional detail on mining depth and
AMM
▪ AMM emissions will remain significant by the end of
the century regardless of future coal production
▪ Methodologies used in this study may help improve
future emission factors and inventories, for example,
with underground CMM and more comprehensive
AMM emissions