Download Fugitives

CGE
Greenhouse Gas Inventory
Hands-on Training Workshop
Energy Sector
1.1
Outline of course (continued)

Fugitives




References
Coal mining and handling
Oil and natural gas systems
Data issues
1.2
Energy Sector –
Fugitive Emissions
1.3
Introduction




Fugitives: the sum of emissions from
accidental discharges, equipment leaks,
filling losses, flaring, pipeline leaks, storage
losses, venting and all other direct emissions
except those from fuel use
Mainly methane
Entrained CO2 can be significant in some
cases
Minor N2O emissions from flaring
1.4
Sources of fugitives

Solid fuels (primarily coal)


mining, handling, processing and
storage
Oil and natural gas systems

exploration, production, processing,
refining, transmission, storage and
distribution
1.5
Coal mining and handling




Release of trapped methane during
mining
In-situ methane content of coal can vary
widely
Most fugitive emissions occur at the
mine
Some residual emissions occur from
post-mining handling / processing
activities
1.6
Surface vs. Underground




Two types of coal mines
Higher emissions for underground mines
Emissions increase with depth of mine
Emissions also depend on gas content of
coal


Some gas may remain in the coal
60%–75% gas released during mining activity
1.7
Abandoned mines





Emissions may continue after the mines
have stopped producing coal
Typically, emissions decline 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
1.8
Controlling emissions

Degasification wells



Gas conservation
Flaring
Use of catalytic combustors on the outlet of
ventilation systems for underground mines
1.9
Monitoring and activity data



Methane content of exhausted ventilation air
(Tier 3)
Coal production (Tier 1 or 2)
Imports and exports by type of coal


Post-mining emission, likely to be minor
Information on the depth of each mine
(Tier 2)
1.10
Tier 1 and Tier 2


Tier 1 global average emission factors
Tier 2 country or basin-specific emission
factors based on actual CH4 content of coal
mined
1.11
Tier 3: Underground mines




Underground mines generally must have ventilation
and degasification systems for safety reasons
Often also degasification wells around mining area
Can use data to estimate emissions or to develop
more specific emission factors
When methane recovery from degasification wells
occurs before mining, emission should be reported in
year coal was actually extracted
1.12
Coal mining issues…





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 surface mines or
post-mining
Methane recovered and combusted for energy
should be included in fuel combustion emissions
No inventory method provided for coal fires
Significant quantities of CO2 can also be released
during mining
1.13
Coal mining data issues (cont.)

Coal statistics usually include primary (hard coal and
lignite) and derived fuels (patent fuel, coke oven coke,
gas coke, brown coal briquettes, coke oven gas and
blast furnace gas). Peat may also be included.

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.
1.14
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>
1.15
Oil and natural gas systems




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
1.16
Emission rates depend on…

Characteristics of hydrocarbons being produced,
processed or handled









Conventional crude oil
Heavy oil
Crude bitumen
Dry gas
i.e.,
methane content of fuel and
leakiness of equipment
Sour gas (more than 10 ppmv of hydrogen sulphide (H2S))
Associated gas
Equipment numbers, type and age
Industry design, operating and maintenance practices
Local regulatory requirements and enforcement
1.17
Emissions from venting and
flaring depend on…





The amount of process activity
Operating practices
On-site utilization opportunities for
methane
Economic access to gas markets
Local regulatory requirements and
enforcement
1.18
Accidental releases…



Difficult to predict
Can be a significant contributor
Can include:







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
1.19
Size of the facility


Oil and gas systems tend to include many
small facilities
Exceptions




Petroleum refineries
Integrated oil sands mining and upgrading
operations
Small facilities likely to contribute most of the
fugitive emissions
Less information available for smaller
facilities
1.20
Oil / Gas composition
Raw natural gas and crude oil contains:



a mixture of hydrocarbons
various impurities including H2O, N2, argon, H2S and
CO2
Impurities are removed by processing, treating or
refining
H2S



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
1.21
Acid gas



By-product of the sweetening process to
remove H2S
May contain large amounts of raw CO2
Regardless of how processed…



sulphur recovery unit
flared or vented
…the raw CO2 is released to the atmosphere
1.22
Patterns of emissions

Emissions increase as you go
upstream through system

Emissions decrease with concentration
of H2S in the produced oil and gas
1.23
Equipment leaks





Tend to be continuous emitters
Low to moderate emission rates
All equipment leaks to some extent
Only a few per cent 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% of the total potential sources
leak, the facility is considered wellmaintained
1.24
Sources of equipment leaks











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
1.25
Trends in equipment leaks



Less leakage as toxic nature of
material increases
Less leakage where gas has been
odorized (thus less leaking in sour gas
sections of systems)
More leakage where equipment is
subjected to frequent thermal cycling,
vibrations or cryogenic service
1.26
Storage losses


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
1.27
Methodologies


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



Only for oil systems
Based on gas to oil ratios
Tier 1: Uses national oil and gas production
data and aggregate emission factors
1.28
Fugitives data

Poor quality and incomplete data about
venting and flaring is common


Contact industry representatives for standard
practices to split venting and flaring
Data about equipment leaks at minor
facilities is unavailable or incomplete


Well-site facilities
Field facilities
1.29
Fugitives data (cont.)




Collection of activity data for fugitives
sources is difficult and resource intensive…
There are no real shortcuts available
First step can be to interview experts in
industry on common practices and
processes…
…have them compare national practices with
those of countries with a known emissions
profile (e.g. an Annex I country).
1.30
Venting and flaring data




Flared if gas poses an odour, health or safety
concern
Otherwise vented
Often inconsistencies in vented and flared
volumes reported by companies
Problem with some vented volumes being
reported as flared
1.31
Oil and gas system data
issues

International production data are expressed on a
net basis (i.e. after shrinkage, losses, reinjection,
and venting and flaring)

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 oil sands
and shale oil

Infrastructure data is more difficult to obtain than
production statistics
1.32
Oil and gas system data
issues (cont.)

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

Information on minor facilities (e.g. wellhead equipment,
pigging stations, field gates and pump stations) may not
be available, even from oil companies

The only infrastructure data potentially required for the
Tier 1 method are well counts and lengths of pipeline

Facility information only required for IPCC Tier 3
1.33
Oil and gas system references

Other methodology manuals:





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:



U.S. Energy Information Administration (EIA)
<www.eia.doe.gov/neic/historic/hinternational.htm>
United Nations Statistics Division (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>
1.34
Oil and gas system references
(cont.)

Oil and Gas Journal <www.ogjresearch.com>:







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
1.35
Documentation & reporting

Transparency and documentation are the
most important characteristic of national
inventories!


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
1.36
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.
1.37
Quiz
20 minutes
1.38
Quiz answers

Energy Quiz 1 (key).doc
1.39
Nitrogen Oxides (NOx)


Indirect greenhouse gases
Fuel combustion activities are the most
significant anthropogenic source of NOx



Energy industries
Mobile sources
Two formation mechanisms:


"fuel NOx"
“thermal NOx"
1.40
Carbon monoxide (CO)



Indirect greenhouse gas
Majority from motor vehicles, but also from
small residential and commercial combustion
Intermediate product of the combustion
process
1.41
Non-Methane Volatile Organic
Compounds (NMVOCs)




Indirect greenhouse gases
Product of incomplete combustion
Mobile sources and residential combustion,
especially biomass combustion
Low emissions for large-combustion plants
1.42
Sulfur dioxide (SO2)




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
1.43
Quiz
20 minutes
1.44
Quiz answers

Fugitives Quiz 1 (key).doc
1.45
1.46
EFDB exercise

Look up available
CH4 emission
factors for
biomass–
agricultural
wastes used for
any type of fuel
combustion…
http://www.ipcc-nggip.iges.or.jp/EFDB/find_ef_s1.php
1.47
EFDB search results
1.48