Recovered gases

1. Scope and Applicability

This PCR covers recovery and supply of combustible industrial by-product gases of solid carbonaceous origin: blast-furnace gas, basic-oxygen converter gas and other individually identified recovered process gases. It excludes coke-oven gas, gasworks gas, natural gas, refinery gases, biogas, and heat recovered by burning process gas without exporting a fuel-gas product. The Chinese category name 回收煤气 denotes recovered industrial fuel gas, rather than every recycled gas. Product definitions follow un-energy-2026; the classification title follows un-cpc-2025.

The concrete reference inventory represents a blast-furnace gas recovery center, with converter-gas co-supply conditional. For a converter-only or another covered gas, construct a separate product-specific package with its own concrete reference identity, measured state and route-specific atomic exchanges; never substitute a blast-furnace UUID. Shared method rules apply, while the representative inventory is not a claim that all plants produce both gases. Fossil-carbon air rows apply only to the fossil fraction; biomass-derived carbon requires separately identified biogenic exchanges.

2. Product Category Identity

Field	Value
canonical_pcr_id	pcr.ores-and-minerals-electricity-gas-and-water.electricity-town-gas-steam-and-hot-water.recovered-gases
classification_refs	CPC 3.0: 17203; un-cpc-2025
covered_products	Recovered solid-carbonaceous industrial fuel gases, including blast-furnace and converter gas
excluded_products	Coke-oven gas; gasworks gas; natural gas; refinery gas; biogas; combustion-only heat recovery
representative_product	Cleaned blast furnace gas
production_route	Capture; cooling and dedusting; gas handling; delivery; conditional flaring and pressure recovery
market_state	Gaseous fuel delivered at a metered recovery-center outlet

3. Reference Flow

Field	Value
What	Supply of cleaned blast furnace gas as the representative recovered-gas product
How much	1 kg of accepted dry cleaned gas; accompanying dry volume stated at 273.15 K and 101.325 kPa absolute pressure
How well	Meets the declared receiving gas-network specification; measured composition, gross and net calorific values and delivery pressure
How long or cycle	One declared representative operating period including normal operation, startups and shutdowns
reference_flow_link	reference_gas

Field	Value
Reference amount	1
Reference product flow	Blast furnace gas 67d9fe25-51ed-4d41-af35-f033a752d042
Reference flow property	Mass 93a60a56-a3c8-11da-a746-0800200b9a66
Reference unit group	Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
Reference unit	kg
Required qualifiers	Source furnace and gas type; fossil/biogenic carbon fraction; dry/wet state; metering temperature and absolute pressure; compressibility; gas composition; gross/net calorific value basis; outlet pressure; dust specification; upstream allocation; geography; period; flaring; delivery point

Declare every required qualifier in the foreground package. Volume alone is not a functional equivalence claim between different gases. Retain measured energy content per reference mass, calculated using measured dry volume and density; report UN statistical energy on a gross-calorific basis without treating it as a net-calorific value.

4. Measurement and Unit Rules

rule_id	Applies to	Required property	Required unit	Rule
gas_state	reference_gas	Mass	kg	Collect accepted dry export mass through cp_export, using corrected dry volume and measured gas density on the same state basis. Correct meters using absolute pressure, temperature, moisture and compressibility; do not assume a wet operating m3 equals a reference m3.
energy_basis	reference_gas; converter_gas	Energy content	MJ	Keep gross and net calorific values distinct, on the same dry volume state; report energy as dry volume multiplied by measured calorific value. No fixed gas-density or heating-value default is supplied.
electricity_units	recovery_electricity; pressure_recovery_electricity	Net calorific value	MJ	Convert metered kWh to MJ by multiplying by 3.6; retain meter records. This electricity identity property is not a calorific-value test of electricity.
solids_state	bf_dust; bf_sludge; bof_dust; bof_sludge	Mass	kg	Retain as-transferred wet mass and dry-solids content separately. Use measured moisture to convert; never equate wet sludge mass with dry dust.

5. System Boundary

Boundary Abstraction

Field	Value
declared_starting_condition	Raw by-product gas handed from its producing furnace to the recovery system, with documented upstream burden
starting_condition_role	Physical foreground inlet, not a zero-burden assumption
product_classification_scope	Recovered industrial fuel gases; CPC 17203 is classification context
recursive_input_rule	Use a measured transfer and one identified supplying process; net internal recirculation out of external exchange totals
upstream_dataset_requirement	Link furnace gas supply, utilities and external treatment to compatible datasets; document any unavailable upstream burden
disclosure	Declare furnace/recovery interface, cleaning route, network limits, gas storage, export meters, flare ownership and upstream allocation

rule_id	Applies to	Rule	source_ids
boundary_recovery	recovery	Include capture, cleaning, cooling, compression, gas holding, handling losses and delivery to the declared outlet. Include owned bypass/flare operation; exclude downstream customer combustion.	eu-iron-steel-2013
boundary_treatment	recovery	Record dust, sludge and wastewater at external-treatment handover and link treatment. Internal reused gas/water are balances, not repeated purchases. Full-combustion converter heat recovery is not a recovered fuel-gas output.	eu-iron-steel-2013
boundary_extend	foreground_package	Add each actual auxiliary, treatment chemical, dust stream and elementary pollutant as a separate identified exchange if present. A missing template row never authorizes a cut-off; substantiate any omission through cp_scope.

6. Process Inventory Structure

Process Map

process_id	process_name	inclusion	inclusion_condition	role	quantitative_reference
recovery	Integrated gas capture, conditioning and delivery	required	Covered fuel-gas recovery center	foreground production	per reference flow

Process: Gas capture, conditioning and delivery (recovery)

Inputs

Product flows

Raw blast furnace gas (raw_bf)

Record the raw gas transferred from ironmaking before cleaning, including moisture and dust state.

• Selected flow: Raw blast furnace gas
• Flow property / unit: Volume / m3
• Amount rule: Collected exchange per reference flow using cp_gas.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_gas
• inclusion_condition: Blast-furnace recovery route.
• Sources: un-energy-2026; eu-iron-steel-2013

Raw converter gas (raw_bof)

Record captured converter gas before dedusting; distinguish diverted gas from accepted fuel gas.

• Selected flow: Raw converter gas
• Flow property / unit: Mass / kg
• Amount rule: Collected exchange per reference flow using cp_gas.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_gas
• inclusion_condition: Converter recovery route.
• Sources: un-energy-2026; eu-iron-steel-2013

Alternating current (recovery_electricity)

Meter capture, gas-cleaning, cooling-water pumps, compression and gas-holder electricity; avoid repeated shared-meter totals.

• Selected flow: Alternating current 4d0361a3-56cc-45f9-aa42-bb9103285bf9
• Flow property / unit: Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66 / MJ
• Unit group: Units of energy 93a60a57-a3c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_utilities.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_utilities
• inclusion_condition: All operating recovery systems.
• Sources: un-energy-2026; eu-iron-steel-2013

Production water for industrial use (scrubber_water)

Record supplied industrial-water makeup, excluding internal recirculation.

• Selected flow: Production water for industrial use 72dcdee6-846a-455a-95d1-942aa7ad3730
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_utilities.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_utilities
• inclusion_condition: Wet scrubbing or industrial-water cooling makeup.
• Sources: un-energy-2026; eu-iron-steel-2013

de-ionised water (cooling_deionised_water)

Record separately supplied deionised-water makeup.

• Selected flow: de-ionised water 4f197bf0-7b3b-11dd-ad8b-0800200c9a66
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_utilities.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_utilities
• inclusion_condition: A deionised-water cooling loop is present.
• Sources: eu-iron-steel-2013

Nitrogen gas (purge_nitrogen)

Record purchased gaseous nitrogen for purging the recovery network.

• Selected flow: Nitrogen gas 92233c86-8e75-441c-94de-03cc91bc7c10
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_utilities.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_utilities
• inclusion_condition: Nitrogen purging is used.
• Sources: eu-iron-steel-2013

Outputs

Product flows

Blast furnace gas (reference_gas)

One kilogram of accepted dry blast furnace gas is supplied at the declared outlet.

• Selected flow: Blast furnace gas 67d9fe25-51ed-4d41-af35-f033a752d042
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: 1 kg
• Value mode: fixed_value
• Specificity: product_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: method_formula
• Collection protocol: cp_export
• inclusion_condition: Representative blast-furnace gas dataset.
• Sources: un-energy-2026; eu-iron-steel-2013

Converter gas (converter_gas)

Record accepted converter gas exported from the same recovery center; keep its mass, density and energy separately.

• Selected flow: Converter gas 631f9452-a270-4d64-9103-de9dede592d2
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_export.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_export
• inclusion_condition: The recovery center also exports converter gas.
• Sources: un-energy-2026; eu-iron-steel-2013

Alternating current (pressure_recovery_electricity)

Record net electricity exported from gas-pressure recovery, excluding self-consumed generation.

• Selected flow: Alternating current 4d0361a3-56cc-45f9-aa42-bb9103285bf9
• Flow property / unit: Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66 / MJ
• Unit group: Units of energy 93a60a57-a3c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_utilities.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_utilities
• inclusion_condition: Top-pressure energy recovery exports electricity.
• Sources: eu-iron-steel-2013

Waste flows

Blast furnace gas-cleaning dust (bf_dust)

Weigh segregated dry dust at handover; retain metal and moisture analysis and receiving route.

• Selected flow: Blast furnace gas-cleaning dust
• Flow property / unit: Mass / kg
• Amount rule: Collected exchange per reference flow using cp_waste.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_waste
• inclusion_condition: Dry coarse gas cleaning is used on the blast-furnace route.
• Sources: un-energy-2026; eu-iron-steel-2013

Blast furnace gas-cleaning sludge (bf_sludge)

Weigh wet sludge and measure dry solids and zinc/lead content; avoid double-counting solids in effluent.

• Selected flow: Blast furnace gas-cleaning sludge
• Flow property / unit: Mass / kg
• Amount rule: Collected exchange per reference flow using cp_waste.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_waste
• inclusion_condition: Wet gas cleaning produces separated sludge.
• Sources: un-energy-2026; eu-iron-steel-2013

Converter gas-cleaning dust (bof_dust)

Weigh converter dry gas-cleaning dust separately from blast-furnace dust.

• Selected flow: Converter gas-cleaning dust
• Flow property / unit: Mass / kg
• Amount rule: Collected exchange per reference flow using cp_waste.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_waste
• inclusion_condition: Dry converter-gas dedusting is used.
• Sources: un-energy-2026; eu-iron-steel-2013

Converter gas-cleaning sludge (bof_sludge)

Weigh converter wet gas-cleaning sludge separately and report dry-solids content.

• Selected flow: Converter gas-cleaning sludge
• Flow property / unit: Mass / kg
• Amount rule: Collected exchange per reference flow using cp_waste.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_waste
• inclusion_condition: Wet converter-gas dedusting is used.
• Sources: un-energy-2026; eu-iron-steel-2013

Gas-scrubber wastewater (scrubber_effluent)

Meter the aqueous effluent handed to wastewater treatment; record suspended solids, cyanide, ammonia and metals analyses.

• Selected flow: Gas-scrubber wastewater
• Flow property / unit: Volume / m3
• Amount rule: Collected exchange per reference flow using cp_waste.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_waste
• inclusion_condition: Scrubber water is purged across the recovery boundary.
• Sources: un-energy-2026; eu-iron-steel-2013

Elementary flows

carbon monoxide (fossil) (carbon_monoxide_air)

Measure or reconcile fossil CO discharged by leaks, venting and incomplete foreground flare combustion.

• Selected flow: carbon monoxide (fossil) 08a91e70-3ddc-11dd-924e-0050c2490048
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_air.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_air
• inclusion_condition: Fossil-carbon gas is released to air.
• Sources: un-energy-2026; eu-iron-steel-2013

carbon dioxide (fossil) (carbon_dioxide_air)

Measure or reconcile fossil CO2 from foreground venting and flaring; include CO2 already in vented gas.

• Selected flow: carbon dioxide (fossil) 08a91e70-3ddc-11dd-923d-0050c2490048
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Unit group: Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collected exchange per reference flow using cp_air.
• Value mode: calculated_value
• Specificity: site_specific
• Normalization basis: per reference flow
• Basis kind: reference_flow
• Evidence kind: calculated_from_collection
• Collection protocol: cp_air
• inclusion_condition: Fossil-carbon gas is vented or flared.
• Sources: un-energy-2026; eu-iron-steel-2013

7. Allocation and Co-product Handling

rule_id	Applies to	Rule	source_ids
allocation_upstream	raw_bf; raw_bof	Obtain the producing-furnace burden allocated to each transferred gas through cp_upstream. Recovery does not establish zero burden or an avoided-emission credit. Disclose supplier allocation and assess uncertainty where burdens are unavailable.
allocation_shared	recovery	Assign dedicated meters directly. For remaining common conditioning services use a documented causal engineering driver, with measured driver totals and shares summing to one in cp_allocation. If no causal driver is defensible, state an economic allocation scenario using consistent-period revenues and provide sensitivity; never silently choose mass, volume or calorific value as universal allocation.
allocation_outputs	converter_gas; pressure_recovery_electricity; bf_dust; bf_sludge; bof_dust; bof_sludge	Treat independently exported gas/electricity as co-products where applicable. Determine dust/sludge product versus waste status from actual handover and quality records, and update the physical flow type accordingly. Do not credit recycling or pressure recovery twice; retain treatment responsibility.

8. Foreground Data Collection, Calculation, and Quality Rules

Data Collection Protocols

protocol_id	process_id	flow_role	record_type	raw_fields	collection_method	unit	frequency	temporal_coverage	site_scope	aggregation_rule	quality_evidence
cp_export	recovery	reference_gas; converter_gas	Export meters and gas laboratory records	Gas type; accepted dry mass; accepted dry volume; temperature; absolute pressure; water vapor; compressibility; composition; density; gross/net calorific value; delivery pressure	Reconcile calibrated export meters with representative gas sampling; obtain dry mass as corrected dry volume multiplied by measured density on that same state basis. Separate gas types and excluded flare diversion.	m3; kg; MJ	Continuous meters; routine composition sampling	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_gas	recovery	raw_bf; raw_bof	Furnace transfer records	Source furnace; inlet volume/mass; state; contaminants; diverted fraction	Reconcile transfer meters and furnace operating logs on matching gas-state bases.	m3; kg	Continuous and each converter heat	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_utilities	recovery	recovery_electricity; scrubber_water; cooling_deionised_water; purge_nitrogen; pressure_recovery_electricity	Dedicated meter and supply records	Meter id; exchange identity; gross input; self-consumption; exported output; allocation driver; unit conversion	Read dedicated electricity, water and nitrogen meters, reconciled to bills; use measured density if volume is converted to mass.	kWh; MJ; kg; m3	Continuous; reconcile monthly	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_waste	recovery	bf_dust; bf_sludge; bof_dust; bof_sludge; scrubber_effluent	Weighbridge, effluent meters and analyses	Origin; mass/volume; moisture; dry solids; metals; cyanide; ammonia; destination; waste status	Measure each segregated waste at external-treatment handover; reconcile manifests and retained laboratory samples.	kg; m3	Each transfer and representative samples	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_air	recovery	carbon_monoxide_air; carbon_dioxide_air	Flare, vent and leak inventory	Event duration; gas flow; composition; fossil fraction; flare operation; monitoring results; uncertainty	Use stack/vent monitoring or a documented event-level carbon balance; retain methods and uncertainties. Account for residual CO and inlet CO2 separately.	kg	Continuous or each event	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_upstream	recovery	raw_bf; raw_bof	Supplying-process and allocation dossier	Supplier; source dataset; furnace boundary; allocation; gas transfer basis; unresolved burden	Obtain and verify a compatible supplying-process dataset and its gas allocation; do not infer burden from gas price alone.	m3; kg	Each supply basis revision	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_allocation	recovery	recovery	Shared-service attribution records	Service; product; driver; measured totals; shares; revenues if used; sensitivity	Separate independently metered service totals; document residual allocation rationale and sum shares to one.	dimensionless	Each accounting period	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty
cp_scope	recovery	recovery	Equipment and exchange completeness register	Unit operations; chemicals; emissions; water loops; omitted exchanges; upstream/treatment links	Walk down the actual recovery system; reconcile every physical crossing, and justify conditional absences and omissions.	not applicable	Each configuration revision	Same declared representative period, including startup and shutdown	Declared recovery center and handover points	per reference flow	Calibrations; logs; source records; reconciliation and uncertainty

Calculation Rules

rule_id	Applies to	Formula or rule	Inputs	Output	source_ids
normalize_records	all inventory rows	For the same declared period, divide each attributable exchange total by accepted exported dry reference-gas mass; the reference output is 1 kg. Preserve numerator units and document allocation before division.	cp_export; cp_gas; cp_utilities; cp_waste; cp_air; cp_allocation	Exchange amount per reference flow
correct_gas_volume	raw_bf; reference_gas	Convert measured gas volume to the declared dry temperature/absolute-pressure basis using measured moisture and compressibility with a documented gas-state calculation or calibrated flow-computer record. Retain the complete conversion record.	cp_gas; cp_export	Dry gas volume at reference conditions
gas_energy	reference_gas; converter_gas	Multiply dry gas volume by its measured gross or net calorific value on the identical state basis; retain both results and never use an unrelated furnace-gas factor.	cp_export	Gross and net energy content, separately	un-energy-2026

Data Quality Requirements

requirement_id	Applies to	Requirement	Evidence
quality_balance	recovery	Reconcile inlet, export, own use, flare, leakage and gas-holder stock changes by gas type. Explain differences against propagated measurement uncertainty.	cp_gas; cp_export; cp_air
quality_state	reference_gas; converter_gas	Declare dry/wet volume and calorific value state; use measured density when reconciling converter mass with volume.	cp_export
quality_completeness	recovery	Retain omitted-flow explanations; add actual route-specific atomic exchanges and identify upstream and external-treatment gaps. No external empirical quantity ranges are prescribed.	cp_scope; cp_upstream

9. Validation Rules

rule_id	Applies to	Rule	source_ids
validate_reference	foreground_package	Require concrete gas identity, accepted reference quantity, all qualifiers, state correction, measured calorific values and matched period/denominator. Reject interchangeable treatment of different gases or wet and dry volumes.	un-energy-2026
validate_exchanges	recovery	Each physical exchange must be atomic; unresolved UUIDs must retain specific physical names and review metadata. Prove conditional absences. Reject double-counted internal circulation, co-products or exported-gas combustion.
validate_balance	recovery	Require documented gas/carbon balances, utilities, waste destinations, measured allocation drivers and upstream-burden disclosure. Investigate negative amounts, unexplained balances and missing flare periods; flag estimates and missing records.

10. Published Dataset Profile

Field	Value
dataset_role	secondary_dataset; background_dataset
downstream_use	Gas supply inputs to receiving industrial processes; downstream process or lifecyclemodel projection
allowed_use	Only matching gas type, state, geography, period and upstream allocation; energy conversion from measured calorific values
excluded_use	Automatic substitution for natural gas or coke-oven gas; energy-only equivalence without quality checks; zero-burden or avoided-emission credits inferred from recovery
required_metadata	Gas identity; state; composition; measured energy; outlet specification; furnace source; period; site; allocation; boundaries; data gaps
required_quality_disclosure	Meter calibrations; sampling; balances; uncertainty; upstream and waste-treatment links; estimates and unresolved identities
update_trigger	Furnace feedstock, cleaning route, gas network, calorific value basis, allocation or supplying-process changes

11. Data Sources

Source id	Type	Reference	Used for
un-cpc-2025	official_guidance	UNSD, Central Product Classification Version 3.0 structure, 30 June 2025, rows 520-525. https://unstats.un.org/unsd/classifications/Econ/Download/In%20Text/CPC_Ver_3.0_Structure_30Jun2025.csv; retrieved 2026-10-01	Classification identity only; independence key: unsd-cpc-3-structure-2025
un-energy-2026	official_guidance	UNSD, Guidelines for the 2024 Annual Questionnaire on Energy Statistics, May 2026, pp. 13-14. https://unstats.un.org/unsd/energystats/questionnaire/documents/Energy-Questionnaire-Guidelines.pdf; retrieved 2026-10-01	Recovered gas definition, exclusions and gross-energy reporting; independence key: unsd-energy-questionnaire-2026
eu-iron-steel-2013	official_guidance	European Commission JRC, Best Available Techniques Reference Document for Iron and Steel Production, 2013, section 6.3.4 pp. 326-327 and section 7.2.2.1.2 pp. 372-373. https://bureau-industrial-transformation.jrc.ec.europa.eu/sites/default/files/2019-11/IS_Adopted_03_2012.pdf; retrieved 2026-10-01	Gas cleaning, wet/dry residues, suppressed combustion and flare diversion; no empirical ranges adopted; independence key: jrc-iron-steel-bref-2013