Transcript Energy - Fugitive Emissions_new

CGE
Greenhouse Gas Inventory
Hands-on Training Workshop
Energy Sector – Fugitive Emissions
Consultative Group of Experts (CGE)
Training Materials for National Greenhouse Gas Inventories
Target Audience and Expectation from Training Material
This training material is suitable for persons with beginner to intermediate level knowledge
of national GHG inventory development.
After having read this Presentation, in combination with the related Handbook, the reader
should:
have an overview of how emissions inventories are developed for the energy sector
(fuel combustion);
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 her/his country’s situation best;
know where to find more detailed information on the topic discussed.
This training material is developed primarily on the basis of methodologies developed,
by the IPCC; hence the reader is always encouraged to refer to the original
documents to further detailed information on a particular issue.
2
Acronyms
IEA
UNSD
International Energy Agency
United Nations Statistics Department
3
Outline of course - Fugitive Emissions
Fugitives

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)
4
1.4
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 (CH4)

Entrained CO2 can be significant in some cases

Minor N2O emissions from flaring
5
1.5
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
6
1.6
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
7
1.7
8
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
9
1.9
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
10
1.10
Controlling Emissions


Degasification wells

Gas conservation

Flaring
Use of catalytic combustors on the outlet of ventilation systems for underground
mines
11
1.11
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)
12
1.12
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
13
1.13
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
14
1.14
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
15
1.15
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.
16
1.16
Coal Mining References

Coal statistics are available for most countries from:



U.S. Energy Information Administration (EIA) <http://www.eia.gov/>
United Nations Statistics Department (UNSD)
< http://unstats.un.org/unsd/default.htm>
International Energy Agency (IEA) <http://www.iea.org/>
17
1.17
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
18
1.18
19
Emission Rates Depend On…

Characteristics of hydrocarbons being produced, processed or handled
i.e.,






Conventional crude oil
methane content of fuel and
leakiness of equipment
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
20
1.20
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
21
1.21
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
22
1.22
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
23
1.23
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
24
1.24
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
25
1.25
Patterns of Emissions

Emissions increase as you go upstream through system

Emissions decrease with concentration of H2S in the produced oil and
gas
26
1.26
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
27
1.27
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
28
1.28
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
29
1.29
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
30
1.30
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
31
1.31
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
32
1.32
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).
33
1.33
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
34
1.34
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
35
1.35
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
36
1.36
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/inter-natlinks/sd_natstat.asp and
http://unstats.un.org/unsd/databases.htm>
International Energy Agency (IEA) <http://www.iea.org/stats/index.asp>
37
1.37
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
38
1.38
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"
39
1.39
Carbon Monoxide (CO)

Indirect greenhouse gas

Majority from motor vehicles, but also from small residential and
commercial combustion

Intermediate product of the combustion process
40
1.40
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
41
1.41
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
42
1.42