CGE Training Materials National Greenhouse Gas Inventories

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CGE Training MaterialsNational Greenhouse Gas
Inventories

• Energy Sector Fugitive Emissions

Version 2, April 2012
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Target Audience and Objectives of the Training
Materials

• These training materials are suitable for people
  with beginner to intermediate level knowledge of
  national greenhouse gas (GHG) inventory
  development.
• After having read this Presentation, in
  combination with the related documentation, the
  reader should
• Have an overview of how emissions inventories are
  developed for the energy sector (fugitive
  emissions)
• Have a general understanding of the methods
  available, as well as of the main challenges in
  that particular area
• Be able to determine which methods suits their
  countrys situation best
• Know where to find more detailed information on
  the topic discussed.
• These training materials have been developed
  primarily on the basis of methodologies developed
  by the IPCC hence the reader is always
  encouraged to refer to the original documents to
  obtain further detailed information on a
  particular issue.

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Acronyms

• IEA International Energy Agency
• ppmv Parts per million by volume
• UNSD United Nations Statistics Department

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Outline of this presentation Fugitive Emissions

• Fugitive emissions
• Introduction (slide 3)
• Coal mining and handling (slide 5)
• Oil and natural gas systems (slide 15)
• Data issues (slide 31)
• References (slides 14, 33, 34)

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Introduction

• Fugitive emissions 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 (CH4)
• Entrained carbon dioxide (CO2) can be significant
  in some cases
• Minor nitrous oxide (N2O) emissions from flaring.

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Sources of Fugitives Emissions

• Solid fuels (primarily coal)
• Mining, handling, processing and storage.
• Oil and natural gas systems
• Exploration, production, processing, refining,
  transmission, storage and distribution.

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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.

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Surface vs. Underground

• Two types of coal mines surface and
  underground.
• Emissions increase with mine depth
• i.e. higher emissions for underground mines.
• Emissions also depend on the gas content of coal
• Some gas may remain in the coal
• 6075 gas released during mining activity.

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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 sources of
  emissions.
• Flooding of mines can prevent emissions.

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Controlling Emissions

• Degasification wells
• Gas conservation
• Flaring.
• Use of catalytic combustors on the outlet of
  ventilation systems for underground mines.

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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).

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Tier 1 and Tier 2
Source IPCC good practice guidance, page 2.70.

• 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

• Underground mines generally must have ventilation
  and degasification systems for safety reasons.
• Often there are also degasification wells around
  the mining area.
• 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 the year the coal was actually extracted.

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Coal Mining Data 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 is 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, 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.

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Coal Mining References

• Coal statistics are available for most countries
  from
• US Energy Information Administration (EIA)
  lthttp//www.eia.gov/gt
• United Nations Statistics Department (UNSD)
• lt http//unstats.un.org/unsd/default.htmgt
• International Energy Agency (IEA)
  lthttp//www.iea.org/gt.

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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.

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Emission Rates Depend On

• Characteristics of the hydrocarbons being
  produced, processed or handled
• Conventional crude oil
• Heavy oil
• Crude bitumen
• Dry gas
• 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.

i.e. methane content of fuel and leakiness of
equipment
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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.

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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.

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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 are likely to contribute most of
  the fugitive emissions.
• Less information is available for smaller
  facilities.

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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

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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.

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Patterns of Emissions

• Emissions increase as you go upstream through
  system.
• Emissions decrease with concentration of H2S in
  the produced oil and gas.

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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 well-maintained.

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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

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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.

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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.

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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-oil ratios.
• Tier 1 Uses national oil and gas production
  data and aggregate emission factors.

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Fugitive Emissions 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.

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Fugitive Emissions Data (cont.)

• Collecting activity data for fugitive 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).

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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.

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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 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.

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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.
• Only facility information is required for the
  IPCC Tier 3 method.

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Oil and Gas System References

• Other methodology manuals
• American Petroleum Institute (API) ltwww.api.orggt
• Canadian Association of Petroleum Producers
  (CAPP) ltwww.capp.cagt
• Canadian Gas Association (CGA) ltwww.cga.cagt
• Gas Technology Institute (GTI) ltwww.gastechnology.
  orggt.
• Oil and gas statistics
• US Energy Information Administration (EIA)
  ltwww.eia.doe.gov/neic/historic/hinternational.htmgt
  
• United Nations Statistics Division (UNSD)
  lthttp//unstats.un.org/unsd/methods/inter-natlinks
  /sd_natstat.asp and http//unstats.un.org/unsd/dat
  abases.htmgt
• International Energy Agency (IEA)
  lthttp//www.iea.org/stats/index.aspgt.

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Oil and Gas System References (cont.)

• Oil and Gas Journal ltwww.ogjresearch.comgt
  includes
• 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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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 is from the nitrogen contained in the
  fuel itself
• Thermal NOx is from nitrogen in the air.

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Carbon Monoxide (CO)

• Indirect greenhouse gas
• Majority of emissions are 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)

• 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)

• Aerosol precursor
• May have a cooling effect on climate
• Concentration increases with burning of fossil
  fuels that contain sulphur
• Closely related to the sulphur content of fuels.

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• Thank you

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