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CGE Greenhouse Gas Inventory
Hands-on Training Workshop
for the African Region
- Energy Sector –
Fugitives
Pretoria, South Africa
18-22 September 2006
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Energy Sector
Fugitive Emissions
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Introduction
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Fugitives: the sum of emissions from
accidental discharges, equipment leaks,
filling losses, flaring, pipeline leaks, storage
losses, venting, flaring, and all other direct
emissions except those from fuel use.
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Mainly methane
Entrained CO2 can be significant in some
cases
Minor N2O emissions from flaring
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Sources of Fugitives
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Solid fuels (primarily coal)
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mining, handling, processing, and
storage
Oil and natural gas systems
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exploration, production, processing,
refining, transmission, storage, and
distribution
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Coal Mining and Handling
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Release of trapped methane during
mining
In-situ methane content of coal can vary
significantly
Most fugitive emissions occur at the
mine
Some residual emissions occurring from
post-mining handling / processing
activities
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Surface vs. Underground
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Two types of coal mines
Higher emissions for underground mines
Emissions increase with depth of mine
Emissions also depend on gas content of
coal
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Some gas may remain in the coal
60-75% gas released during mining activity
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Abandoned mines
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Emissions may continue after the mines
have stopped producing coal
Typically, emissions decay rapidly once deep
mine coal production stops
In some cases, emissions by the surrounding
strata may be significant and continue for
years afterwards.
Coal waste or reject piles are minor source of
emissions
Flooding of mines can prevent emissions
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Controlling Emissions
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Degasification wells
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Gas conservation
Flaring
Use of catalytic combustors on the outlet of
ventilation systems for underground mines
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Monitoring and Activity Data
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Methane content of exhausted ventilation air
(Tier 3)
Coal production (Tier 1 or 2)
Imports and exports by type of coal
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post-mining emission, likely to be minor
Information on the depth of each mine
(Tier 2)
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Tier 1 and Tier 2
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Tier 1 global average emission factors
Tier 2 country or basin-specific emission
factors based on actual CH4 content of coal
mined
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Tier 3: Underground mines
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Underground mines generally must have
ventilation and degasification systems for
safety reasons
Often also includes degasification wells
around mining area
Can use data to actually estimate emissions
or to develop more specific emission factors.
When methane recovery from degasification
wells occurs before mining, emission should
be reporting in year coal was actually
extracted.
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Coal mining issues…
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Initial focus can be on most “gassy” mines for
Tier 3 approach, and apply Tier 1 or 2 for
other mines.
Tier 3 not likely to be feasible for for surface
mines or post-mining
Methane recovered and combusted for
energy should be included in fuel combustion
emissions
No method provided for coal fires
Significant quantities of CO2 can also be
released during mining
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Coal Mining Data Issues (cont.)

Coal statistics usually include primary (hard coal and
lignite) and derived fuels (patent fuel, coke oven coke,
gas coke, BKB, coke oven gas and blast furnace gas).
Peat may also be included.
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No information is typically provided on the method of
mining (i.e., surface or underground) or the depth of
the mines. A conservative approximation is to assume
that lignite coal is surface mined and bituminous and
anthracite coal is from underground mines.

Some useful unpublished data, including mine depth,
are available from IEA upon special request.
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Coal Mining References

Coal statistics are available for most countries
from the
 U.S. Energy Information Administration (EIA)
(www.eia.doe.gov),
 United Nations Statistics Department (UNSD)
(http://unstats.un.org/unsd/)
 International Energy Agency (IEA)
(www.iea.org)
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Oil and Natural Gas Systems
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Equipment leaks
Process venting and flaring
Evaporation losses (i.e., from product
storage and handling, particularly where
flashing losses occur)
Accidental releases or equipment failures
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Emission rates depend on…
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Characteristics of hydrocarbons being produced,
processed or handled
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conventional crude oil
heavy oil
crude bitumen
dry gas
sour gas
associated gas
i.e.,
methane content of fuel and
leakiness of equipment
Equipment numbers, type, and age
Industry design, operating, and maintenance
practices
Local regulatory requirements and enforcement
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Emissions from venting and
flaring depend on…
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The amount of process activity
Operating practices
Onsite utilization opportunities for
methane
Economic access to gas markets
Local regulatory requirements and
enforcement
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Accidental Releases…
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Difficult to predict
Can be a significant contributor
Can include:
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well blowouts
pipeline breaks
tanker accidents
tank explosions
gas migration to the surface around the
outside of wells
surface casing vent blows
leakage from abandoned wells
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Size of the facility
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Oil and gas systems tend to include many
small facilities
Exceptions
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petroleum refineries
integrated oilsands mining and upgrading
operations
Small facilities likely to contribute most of the
fugitive emissions
Less information available for smaller
facilities
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Oil / Gas Composition
Raw natural gas and crude oil contains:
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a mixture of hydrocarbons
various impurities including H2O, N2, Ar, H2S and CO2
Impurities are removed by processing, treating or refining
H2S
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Sour gas if more than 10 ppmv of H2S
Sweet gas if less than 10 ppmv of H2S
The concentration of H2S tends to increase with the depth
of the well.
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Acid Gas
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By-product of the sweetening process to
remove H2S
May contain large amounts of raw CO2
Regardless of how processed…
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sulphur recovery unit
flared or vented
…the raw CO2 is released to the atmosphere
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Patterns of Emissions
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Emissions increase as you go
upstream through system
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Emissions decrease with concentration
of hydrogen sulphide (H2S) in the
produced oil and gas
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Equipment Leaks
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Tend to be continuous emitters
Low to moderate emission rates
All equipment leaks to some extent
Only a few percent of the potential sources
at a site actually leak sufficiently at any time
to be in need of repair or replacement.
If less than 2 percent of the total potential
sources leak, the facility is considered wellmaintained
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Sources of Equipment Leaks
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Valves
Flanges and other connections
Pumps
Compressors
Pressure relief devices
Process drains
Open-ended valves
Pump and compressor seal system degassing vents
Accumulator vessel vents
Agitator seals
Access door seals
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Trends in Equipment Leaks
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Leaking decreases as toxic nature
increases
Leaking decreases as where gas has
been odorized, thus less leaking in
sour gas sections of systems
Leaks more when subjected to
frequent thermal cycling, vibrations, or
cryogenic service
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Storage Losses
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Boiling or flashing losses of methane occur
from storage tanks
Occurs at production and processing
facilities where hydrocarbon liquid flows
directly from a pressure vessel where it has
been in contact with natural gas
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Methodologies
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Tier 3: Requires detailed inventories of
equipment, infrastructure, and bottom-up
emission factors
Tier 2: Based on a mass balance estimate of
the maximum amount of methane that could
be emitted
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Only for oil systems
Based on gas to oil ratios
Tier 1: Uses national oil and gas production
data and aggregate emission factors
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Fugitives Data
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Poor quality and incomplete data about
venting and flaring is common
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Contact industry representatives for standard
practices to split venting and flaring
Data on equipment leaks at minor facilities
are often unavailable or incomplete
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Well-site facilities
Field facilities
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Fugitives Data (cont.)
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Collection of activity data for fugitives
sources is difficult and resource intensive…
There are no real shortcuts available
First steps can be to interview experts in
industry on common practices and
processes…
…have then compare national practices with
those of countries with known emissions
profile (e.g., an Annex I country).
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Venting and Flaring Data
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Flared if gas poses an odour, health, or
safety concern
Otherwise vented
Often inconsistencies in reported vented and
flared volumes by companies
Problem with some vented volumes being
reported as flared
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Oil and Gas System Data
Issues

International production data are expressed on a
net basis (i.e., after shrinkage, losses,
reinjection, and vented and flared)
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Crude oil normally includes hydrocarbon liquids
from oil wells and lease condensate (separator
liquids) recovered at natural gas facilities. May
also include synthetic crude oil from oilsands and
shale oil.
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Infrastructure data is more difficult to obtain than
production statistics
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Oil and Gas System Data
Issues (cont.)
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Information on the numbers and types of major facilities,
types of processes used at these facilities, numbers and
types of active wells, numbers of wells drilled, and
lengths of pipeline are typically only available from
national agencies.
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Information on minor facilities (e.g., wellhead equipment,
pigging stations, field gates, and pump stations) may not
be available, even from oil companies.
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The only infrastructure data potentially required for Tier 1
approach are well counts and lengths of pipeline
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Detailed facility information required for IPCC Tier 3
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Oil and Gas System
References
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Other methodology manuals:
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American Petroleum Institute (API) (www.api.org)
Canadian Association of Petroleum Producers (CAPP)
(www.capp.ca)
Canadian Gas Association (CGA) (www.cga.ca)
Gas Technology Institute (GTI) (www.gastechnology.org)
Oil and gas statistics:
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U.S. Energy Information Administration (EIA)
(www.eia.doe.gov/neic/historic/hinternational.htm)
United Nations Statistics Department (UNSD)
(http://unstats.un.org/unsd/methods/internatlinks/sd_natstat.htm and
http://unstats.un.org/unsd/databases.htm)
International Energy Agency (IEA)
www.iea.org/statist/index.htm
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Oil and Gas System
References (cont.)
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Oil and Gas Journal (www.ogjresearch.com):
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Some infrastructure data (number of wells, gas
plant listing, major project announcements)
Worldwide refinery, pipeline and gas processing
projects
Historical refinery, pipeline and gas processing
projects
Worldwide oil field production survey
Worldwide refining survey
Worldwide gas processing survey
Enhanced oil recovery survey
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- Closing -
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Documentation & Reporting
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Transparency and documentation are the
most important characteristic of national
inventories!
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Unless it is documented, then there is nothing
to show that it was done or done correctly
Electronic reporting greatly facilitates the
work of the UNFCCC Secretariat
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Final remarks…
A national inventory is not a research project…
It is a national program that works closely with
statistical and research institutions to create
high quality emissions data.
Please feel free to email me in the future:
Michael Gillenwater
[email protected]
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Extra slides
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Quiz
20 minutes
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Quiz answers
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Energy Quiz 1 (key).doc
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Nitrogen Oxides (NOx)
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Indirect greenhouse gases
Fuel combustion activities are the most
significant anthropogenic source of NOx
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energy industries
mobile sources
Two formation mechanisms:
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"fuel NOx"
“thermal NOx"
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Carbon monoxide (CO)
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Indirect greenhouse gas.
Majority from motor vehicles, but also from
small residential and commercial combustion
Intermediate product of the combustion
process
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Non-Methane Volatile Organic
Compounds (NMVOCs)
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Indirect greenhouse gases
Product of incomplete combustion
Mobile sources and residential combustion,
especially biomass combustion
Low emissions for large-combustion plants
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Sulfur dioxide (SO2)
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Aerosol precursor
May have a cooling effect on climate
Concentration increases with burning of
fossil fuels that contain sulfur
Closely related to the sulfur content of fuels
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Quiz
20 minutes
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Quiz answers

Fugitives Quiz 1 (key).doc
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EFDB Exercise
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Look up available
CH4 emission
factors for
biomassagricultural
wastes used for
any type of fuel
combustion…
http://www.ipcc-nggip.iges.or.jp/EFDB/find_ef_s1.php
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EFDB search results
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