Transcript CGE Greenhouse Gas Inventory Hands-on Training Workshop for the African Region - Energy Sector – Combustion Pretoria, South Africa 18-22 September 2006

CGE Greenhouse Gas Inventory
Hands-on Training Workshop
for the African Region
- Energy Sector –
Combustion
Pretoria, South Africa
18-22 September 2006
1
Outline of Course
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Fuel combustion (Today)
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References
Basic Emission Processes
Methodologies
Relationships with other sources and sectors
Uncertainty
Quality control and completeness
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Outline of Course (continued)
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Fugitives (Tomorrow)
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References
Coal mining and handling
Oil and natural gas systems
Data issues
3
Survey says…?
Audience poll…
 Who has prepared a national inventory for
your country?
 Who has worked on the Energy Sector?
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Please share your…
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Problems you have faced with preparing
estimates for the Energy Sector
Plans for the future to improve your inventory
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Reference materials
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UNFCCC (COP decisions, reporting
guidelines, etc.)
IPCC
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Revised 1996 IPCC Guidelines
Good Practice Guidance
Emission Factor Database (EFDB)
IPCC WG I Assessment Reports
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Use “old” SAR GWP values for reporting
International Energy Agency
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IPCC Guidance
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Fundamental methods laid out in 1996 Revised
Guidelines
IPCC Good Practice clarifies some issues (e.g.,
international bunker fuels) and provides some
updated factors…
…but no significant changes made for fuel
combustion!
2006 IPCC Guidelines provides new information
on Non-Energy Use, new Tier 2 method for oil
systems fugitives, & guidance on abandoned
coal mines
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Key Category Analysis
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Level assessment based on share of total national
emissions for each source category
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Trend assessment based on contribution of
category to changes in emission trends
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Qualitative criteria
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Key Category Analysis
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Idea of key sources based on a measure of
which sources contribute to uncertainty in
inventory
Most if not all source categories in the
Energy Sector will be Key Source Categories
Analysis only as good as original emissions
data.
You probably already know your key
categories.
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Energy Sector
Fuel Combustion
Emissions
9
0
Liberia
Benin
Ghana
400
Angola
Morocco
Libya
Kenya
Uganda
Ethiopia
Tanzania
Zimbabwe
Madagascar
Côte d'Ivoire
Cameroon
Sudan
Egypt
Zambia
Congo, D.R.
Nigeria
South Africa
Tg CO2-eq.
African GHG Emissions (Top 20)
450
Total Emissions
Energy Emissions
350
300
250
200
150
100
50
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Stationary Sources
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Energy Industries
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Manufacturing Industries and Construction
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extraction, production and transformation
electricity generation, petroleum refining
autoproduction of electricity
iron and steel production
non-ferrous metal production
chemical manufacturing
pulp, paper and print
food processing, beverages and tobacco
Commercial/Institutional
Residential
Agriculture/Forestry/Fisheries
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Autoproducers
Note: p. 1.32 of the IPCC Guidelines, Reference Manual - Volume 3
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Mobile Sources
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Civil Aviation
Road Transportation
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Cars
Light duty trucks
Heavy duty trucks and buses
Motorcycles
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Railways
Navigation
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International Bunker Fuels are reported separately
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Carbon dioxide (CO2)
emissions
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Methodology is mass balance-based
Oxidation of the carbon in fuels during
combustion
In perfect combustion conditions, total
carbon content of fuels would be converted
to CO2
Real combustion processes result in small
amounts of partially oxidized and
unoxidized carbon
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Carbon Flow for a typical
Combustion Process
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Most carbon is emitted as CO2 immediately
Small fraction emitted as non-CO2 gases
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CH4, CO, NMVOCs
Ultimately oxidizes to CO2 in the atmosphere
Integrated into overall calculation of CO2
emissions
Remaining part of the fuel carbon is unburned
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Assumed to remain as solid (ash and soot)
Account by using oxidation factors
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Non-CO2 emissions
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Direct greenhouse gases
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Methane (CH4)
Nitrous oxide (N2O)
Precursors and SO2
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Nitrogen oxides (NOx)
Carbon monoxide (CO)
Non-methane volatile organic compounds
(NMVOCs)
Sulfur dioxide (SO2)
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Non-CO2 requires detailed
process information
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Combustion conditions
Size and vintage of the combustion
technology
Maintenance
Operational practices
Emission controls
Fuel characteristics
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Methane (CH4)
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Emissions a function of:
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methane content of the fuel
hydrocarbons passing unburnt through engine
engine type
post-combustion controls
Depends on temperature in boiler/kiln/stove
Highest emissions in residential applications
(e.g., small stoves, open biomass burning,
charcoal production)
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Nitrous Oxide (N2O)
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Lower combustion temperatures tend to lead to
higher N2O emissions
Emission controls (catalysts) on vehicles can
increase the rate of N2O generation, depending
on:
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driving practices (i.e., number of cold starts)
type and age of the catalyst
Significant emissions for countries with a high
penetration of vehicles with catalysts
http://unfccc.int/resource/docs/2004/sbsta/inf03.pdf
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Methods for CO2
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‘Reference Approach’ (Tier 1)
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‘Sectoral Approach’ (Tier 1)
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estimates based on national energy balance
(production + imports - exports) by fuel type without
information on activities
performed quickly if basic energy balance sheet is
available
way of cross-checking emission estimates of CO2 with
the Sectoral Approach
Estimates based on fuel consumption data by sectoral
activity
‘Bottom-Up Approaches’ (Tier 2 or 3)
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More detailed activity and fuel data
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Fundamental Equation
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Six basic steps
1.
2.
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6.
Collect fuel consumption data
Convert fuel data to a common energy unit
Select carbon content factors for each fossil
fuel/product type and estimate the total
carbon content of fuels consumed
Subtract the amount of carbon stored in
products for long periods of time
Multiply by an oxidation factor
Convert carbon to full molecular weight of
CO2 and sum across all fuels
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1. Consumption Data
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Reference Approach:
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Sectoral Approach:
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Estimate apparent consumption of fuels
within the country
Collect actual consumption statistics by fuel
type and economic sector
Tier 2 or 3:
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Collect actual fuel consumption statistics by
fuel type, economic sector, and combustion
technology type
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Data Collection Issues
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IPCC sectoral approach can still be used
even if energy data are not collected using
same sector categories
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focus on completeness and use judgment or
proxy data to allocate to various subsectors
Biomass combustion not needed for CO2, but
reported for information purposes
Informal sector fuel use is important issue if
not captured in energy statistics
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household kerosene use can be
approximated based on expert judgment or
proxy data
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2. Common Energy Unit
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Convert fuel data to a common energy unit
Production and consumption of solid and
liquid fuels in tons
Gaseous fuels in cubic meters
Original units converted into energy units
using calorific values (i.e., heating values)
Reference approach: use different calorific
values for production, imports, and exports
Calorific values used should be reported
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3. Estimate total carbon
content of fuels consumed
Natural Gas
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Depends on composition (methane, ethane, propane,
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butane, and heavier hydrocarbons)
Natural gas flared at the production site will usually be "wet“
- its carbon content factor will be different
Typical: 15 to 17 tons C/TJ
Oil
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Lower carbon content for light refined petroleum products
such as gasoline
Higher for heavier products such as residual fuel oil
Typical for crude oil is 20 ton C/TJ
Coal
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Depend on coal's rank and composition of hydrogen, sulfur,
ash, oxygen, and nitrogen
Typical ranges from 25 to 28 ton C/TJ
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4. Subtract non-energy uses
Oil refineries: asphalt and bitumen for road construction,
naphthas, lubricants, and plastics
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Natural gas: for ammonia production
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Liquid petroleum gas (LPG): solvents and synthetic rubber
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Coking: metals industry
Attempt to use country-specific data instead of IPCC default
carbon storage factors.
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5. Oxidation Factor
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Multiply by an oxidation
factor to account for the
small amount of unoxidized
carbon that is left in ash or
soot.
Amount of carbon
remaining unoxidized
should be low for oil and
natural gas combustion…
…but can be larger and
more variable for coal
combustion
When national oxidation
factors are not available,
use IPCC default factors
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Oxidation Factor Values
Natural Gas
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Less than 1 percent left unburned
Remains as soot in the burner, stack, or
environment
IPCC default oxidation factor = 99.5%
Higher for flares in the oil and gas industry
Closer to 100% for efficient turbines
Oil
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1.5 ± 1 percent left unburned
IPCC default oxidation factor = 99%
Recent research has shown 100% in autos
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Oxidation Factor Values (cont.)
Coal
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Range from 0.6 to 6.6 percent unburned
Primarily in the form of bottom and fly ash
IPCC default oxidation factor = 98%
Biomass
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Can range widely, especially for open
combustion
For closed combustion (e.g., boiler) range
from 1 to 10 percent
No IPCC default
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6. Convert to full molecular
weight and sum
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Convert carbon to full molecular weight of
CO2 and summation across all fuels
To express the results as carbon dioxide
(CO2), multiply the quantity of carbon
oxidized by the molecular weight ratio of
CO2 to C (44:12)
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International Bunker Fuels
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CO2 emissions arising from fuels used in
ships or aircraft for international transport not
be included in the national total
Fuels delivered to and consumed by
international bunkers should be subtracted
from the fuel supply to the country
Bunker fuel emissions should be mentioned
in a separate table as a memo item
See IPCC decision trees on marine and
aviation transport emission allocation
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Biomass Fuels
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CO2 emissions should not be included in national
emission totals from fuel combustion
Reported for information only…
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household fuelwood
ethanol & biodiesel for transport
Account for mixed fuels (e.g., ethanol blends)
Net CO2 emissions implicitly accounted for under
the Land Use Change and Forestry Sector
Non-CO2 emissions from biomass combustion
should be estimated and reported under the
Energy Sector!
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Methods for Non-CO2
emissions
Tier 1
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Multiply fuel consumed by an average emission factor
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Do not require detailed activity data
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Rely on widely available fuel supply data that assume an
average combustion technology is used
Tiers 2/3
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Multiply fuel consumed by detailed fuel type and technologyspecific emission factors
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Tier 2 methods use data that is disaggregated according to
technology types
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Tier 3 methods estimate emissions according to activity
types (km traveled or ton-km carried) and specific fuel
efficiency or fuel rates
Use most disaggregated technology-specific and country-specific
emission factors available
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Fundamental Equation
Emissions =
Σ(Emission Factorabc • Fuel Consumptionabc)
Where,
a = fuel type
b = sector activity
c = technology type including emissions controls
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Stationary Combustion
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Default emission factors for CH4, N2O, NOx,
CO, & NMVOCs by major technology and
fuel types are presented in the IPCC
Guidelines
Most notable: CH4 emissions from open
burning and biomass combustion
Charcoal production is likely to produce
methane emissions at a rate that is several
orders of magnitude greater other
combustion processes
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Mobile Combustion
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Major transport activity (road, air, rail, and
ships)
Most notable: N2O emissions from road
transportation, affected by the type of
emission control technologies
Non-Annex I countries should focus their
efforts on collecting data on the number of
vehicles with catalytic emissions control
devices that operate in their country
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Mobile combustion (cont.)
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Road transport activity data
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assume vast majority of motor gasoline used
for transport
Check data with equipment counts or vehicle
sales/import/export data
Base assumptions of vehicle type and
emission control technology on vehicle
vintage data (i.e., model year of sale) and
assumed activity level (i.e., vkt/vehicle)
Consider national emission standards, leaded
gasoline prevalence, and compliance with
standards
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Relationships with Other
Sources and Sectors
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Industrial Processes Sector
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non-energy fossil fuel feedstocks data, if
available, may not be reliable
petrochemical “feedstocks” may actually be
used for energy
coal purchased by iron and steel industry
may be used to make coke
focus on petrochemical industry and metal
production (e.g., iron and steel)
conservative estimate: Assume plastics,
asphalt, and some lubricants stored
subtract carbon content from these products
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Relationships with Other
Sources and Sectors (cont.)
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Waste Sector
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Land-Use Change and Forestry Sector
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combustion of wastes for energy purposes
included in Energy Sector
incineration of plastics
biomass carbon implicitly accounted for
Autoproduction of electricity
Fuel use for military purposes
Mobile sources in Agriculture
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Quality control and
completeness checks
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All gases (CO2, CH4, and N2O)
All source and sub-source categories
All national territories addressed
Bunker fuels and military operations
All fossil fuel fired electric power stations
Blast furnaces and coke production
Waste combustion with energy recovery
Black market fuels
Non-metered fuel use for pipelines by
compressor stations
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Uncertainty
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Uncertainty in carbon content and calorific values for
fuels is related to the variability in fuel composition
and frequency of actual measurements. Likely to be
small for all countries.
For most non-Annex I countries, the uncertainty in
activity data (i.e., fuel consumption data) will the
dominant issue!
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effort should focus on collection of fuel consumption
data
country-specific carbon content factors are unlikely to
improve CO2 estimates significantly
It is important to document the likely causes of
uncertainty and discuss steps taken to reduce
uncertainties.
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IPCC Software and reporting
tables
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Software to aid in preparation of
greenhouse gas inventories
Provides IPCC default (i.e., Tier 1) methods
National factors can be used where
available
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