CGE Greenhouse Gas Inventory Hands-on Training Workshop for the African Region - Energy Sector

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CGE Greenhouse Gas Inventory Hands-on Training
Workshopfor the African Region- Energy Sector
FugitivesPretoria, South Africa18-22
September 2006
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Energy Sector Fugitive Emissions
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Introduction

• 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.
• Mainly methane
• Entrained CO2 can be significant in some cases
• Minor N2O emissions from flaring

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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

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Coal Mining and Handling

• 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

• 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

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Abandoned mines

• 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

• 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

• 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 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

• 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.
• 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

• 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 hydrocarbons being produced,
  processed or handled
• conventional crude oil
• heavy oil
• crude bitumen
• dry gas
• sour gas
• 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
• Onsite 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 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
• a mixture of hydrocarbons
• various impurities including H2O, N2, Ar, 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.

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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 hydrogen
  sulphide (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 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
  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
• Access door seals

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Trends in Equipment Leaks

• 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

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

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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 on equipment leaks at minor facilities are
  often unavailable or incomplete
• Well-site facilities
• Field facilities

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Fugitives Data (cont.)

• 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

• 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)
• 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.
• 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 Tier 1 approach are well counts and lengths
  of pipeline
• Detailed facility information required for IPCC
  Tier 3

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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 Department (UNSD)
  (http//unstats.un.org/unsd/methods/inter-natlinks
  /sd_natstat.htm and http//unstats.un.org/unsd/dat
  abases.htm)
• International Energy Agency (IEA)
  www.iea.org/statist/index.htm

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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

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- Closing -
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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

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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
• gillenwater_at_alum.mit.edu

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Extra slides
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Quiz

• 20 minutes

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Quiz answers

• Energy Quiz 1 (key).doc

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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"
• thermal NOx"

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Carbon monoxide (CO)

• 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)

• 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 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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(No Transcript)
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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.p
hp
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EFDB search results