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CGE Greenhouse Gas Inventory Hands-on Training Workshop

for the African Region

- Energy Sector –Fugitives

Pretoria, 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 CompositionRaw 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/databases.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@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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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

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EFDB search results