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
CombustionPretoria, South Africa18-22
September 2006
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Outline of Course

• Fuel combustion (Today)
• References
• Basic Emission Processes
• Methodologies
• Relationships with other sources and sectors
• Uncertainty
• Quality control and completeness

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Outline of Course (continued)

• Fugitives (Tomorrow)
• References
• Coal mining and handling
• Oil and natural gas systems
• Data issues

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Survey says?

• Audience poll
• Who has prepared a national inventory for your
  country?
• Who has worked on the Energy Sector?
• Please share your
• 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

• UNFCCC (COP decisions, reporting guidelines,
  etc.)
• IPCC
• Revised 1996 IPCC Guidelines
• Good Practice Guidance
• Emission Factor Database (EFDB)
• IPCC WG I Assessment Reports
• Use old SAR GWP values for reporting
• International Energy Agency

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IPCC Guidance

• 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

• Level assessment based on share of total national
  emissions for each source category
• Trend assessment based on contribution of
  category to changes in emission trends
• Qualitative criteria

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Key Category Analysis

• 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 SectorFuel Combustion Emissions
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African GHG Emissions (Top 20)
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Stationary Sources

• Energy Industries
• extraction, production and transformation
• electricity generation, petroleum refining
• autoproduction of electricity
• Manufacturing Industries and Construction
• 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
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Mobile Sources

• Civil Aviation
• Road Transportation
• Cars
• Light duty trucks
• Heavy duty trucks and buses
• Motorcycles
• Railways
• Navigation
• International Bunker Fuels are reported
  separately

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Carbon dioxide (CO2) emissions

• 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

• Most carbon is emitted as CO2 immediately
• Small fraction emitted as non-CO2 gases
• 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
• Assumed to remain as solid (ash and soot)
• Account by using oxidation factors

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Non-CO2 emissions

• Direct greenhouse gases
• Methane (CH4)
• Nitrous oxide (N2O)
• Precursors and SO2
• 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

• Combustion conditions
• Size and vintage of the combustion technology
• Maintenance
• Operational practices
• Emission controls
• Fuel characteristics

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Methane (CH4)

• Emissions a function of
• 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)

• Lower combustion temperatures tend to lead to
  higher N2O emissions
• Emission controls (catalysts) on vehicles can
  increase the rate of N2O generation, depending
  on
• 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.p
  df

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Methods for CO2

• Reference Approach (Tier 1)
• 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
• Sectoral Approach (Tier 1)
• Estimates based on fuel consumption data by
  sectoral activity
• Bottom-Up Approaches (Tier 2 or 3)
• More detailed activity and fuel data

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Fundamental Equation
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Six basic steps

• 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

• Reference Approach
• Estimate apparent consumption of fuels within the
  country
• Sectoral Approach
• Collect actual consumption statistics by fuel
  type and economic sector
• Tier 2 or 3
• Collect actual fuel consumption statistics by
  fuel type, economic sector, and combustion
  technology type

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Data Collection Issues

• IPCC sectoral approach can still be used even if
  energy data are not collected using same sector
  categories
• 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
• household kerosene use can be approximated based
  on expert judgment or proxy data

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2. Common Energy Unit

• 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
• Depends on composition (methane, ethane, propane,
  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
• 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
• 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
• Natural gas for ammonia production
• Liquid petroleum gas (LPG) solvents and
  synthetic rubber
• Coking metals industry
• Attempt to use country-specific data instead of
  IPCC default carbon storage factors.

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5. Oxidation Factor

• 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
• 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
• 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
• Range from 0.6 to 6.6 percent unburned
• Primarily in the form of bottom and fly ash
• IPCC default oxidation factor 98
• Biomass
• 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

• 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 (4412)

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International Bunker Fuels

• 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

• CO2 emissions should not be included in national
  emission totals from fuel combustion
• Reported for information only
• 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
• Multiply fuel consumed by an average emission
  factor
• Do not require detailed activity data
• Rely on widely available fuel supply data that
  assume an average combustion technology is used
• Tiers 2/3
• Multiply fuel consumed by detailed fuel type and
  technology-specific emission factors
• Tier 2 methods use data that is disaggregated
  according to technology types
• 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
• S(Emission Factorabc Fuel Consumptionabc)
• Where,
• a fuel type
• b sector activity
• c technology type including emissions controls

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Stationary Combustion

• 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

• 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.)

• Road transport activity data
• 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

• Industrial Processes Sector
• 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.)

• Waste Sector
• combustion of wastes for energy purposes included
  in Energy Sector
• incineration of plastics
• Land-Use Change and Forestry Sector
• 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

• 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

• 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!
• 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

• Software to aid in preparation of greenhouse gas
  inventories
• Provides IPCC default (i.e., Tier 1) methods
• National factors can be used where available