Process emissions: what to collect by industry

Process emissions are the trickiest part of Scope 1 to get right — they have nothing to do with energy use, the formulas vary by industry, and the emission factor has to come from your own equipment, raw materials or sector methodology. This guide walks you through what they are, what to collect, and how to enter them in Dcycle.

In Dcycle, process emissions always use a custom emission factor

Because every process is different, Dcycle does not ship a default factor library for industrial processes. You enter the activity data (raw material processed, product produced, gas leaked) and the custom emission factor you've calculated or sourced — Dcycle multiplies them, applies the GWP and assigns the result to Scope 1. The rest of this guide explains how to obtain that factor.

What are process emissions?

Under the GHG Protocol, process emissions are direct greenhouse gases released by a chemical or physical transformation other than fuel combustion. Two examples make this concrete:

Cement. Limestone (CaCO₃) is heated in a kiln and becomes clinker (CaO) plus CO₂. About 60% of the CO₂ from cement-making comes from this reaction — it would happen even with a zero-carbon energy source. That CO₂ is a process emission. The fuel burned in the kiln to reach 1,450 °C is separate — that’s stationary combustion.
Aluminium. During electrolysis of alumina, carbon anodes react with oxygen and release CO₂, plus small but powerful amounts of perfluorocarbons (CF₄, C₂F₆) during “anode effects”. The electrolysis energy is Scope 2; the gases from the reaction itself are process emissions.

Rule of thumb: if the gas is released because of what your raw material becomes, not because you burned something to power the transformation, it’s a process emission.

Which industries have process emissions?

Industry	Typical sources
Cement, lime, dolomite	Calcination of carbonates (CaCO₃, MgCO₃) → CO₂
Iron & steel	Carbon in coke / fluxes / scrap → CO₂; pig iron production
Aluminium	Carbon anode consumption → CO₂; anode effects → PFCs
Glass, ceramics	Carbonate decomposition (soda ash, limestone) → CO₂
Chemicals	Ammonia, nitric acid, adipic acid (→ N₂O); ethylene, hydrogen, carbon black (→ CO₂)
Fertilisers	Urea production, nitric acid (→ N₂O)
Pulp & paper	Limestone in lime kiln (→ CO₂); chemical recovery
Electronics	Etching and cleaning gases (HFCs, PFCs, NF₃, SF₆)
Electrical equipment	SF₆ leakage from switchgear

If your activity doesn’t appear here, you probably have no process emissions and can skip this section.

The two ways to calculate them

The GHG Protocol allows two approaches, in order of preference:

Direct measurement (Tier 3). Continuous monitoring of stack emissions. Most accurate but rare outside heavily regulated plants.
Activity data × emission factor (Tier 1 or Tier 2). Multiply how much of a raw material you processed by an emission factor.
- Tier 1 uses a default factor (IPCC, EU ETS Annex IV, national inventory).
- Tier 2 uses a factor specific to your raw material composition or technology.

Dcycle supports Tier 1 and Tier 2 by letting you enter a custom emission factor.

The general formula:

Emissions (kg CO₂e) = Activity data × Emission factor × Global Warming Potential

For CO₂, GWP = 1, so the GWP step disappears. For PFCs, N₂O, SF₆ etc., Dcycle applies the IPCC AR6 GWP automatically when you select the gas.

What to collect

For each process emission line, gather:

Field	Required	Notes
Facility	Required	The production site
Process category	Required	E.g. “cement calcination”, “ammonia production”, “SF₆ leakage”
Greenhouse gas	Required	CO₂, CH₄, N₂O, PFCs, HFCs, SF₆, NF₃
Activity data quantity	Required	Tonnes of raw material, tonnes of product, or kg of gas refilled
Activity data unit	Required	tonnes, kg, m³
Start date / End date	Required	Measurement or reporting period
Custom emission factor (value)	Required	The numerical factor you calculated or sourced — see below
Custom emission factor (unit)	Required	E.g. t CO₂ / t clinker, kg N₂O / t HNO₃
Emission factor source	Recommended	IPCC, EU ETS, supplier disclosure, internal measurement, etc. — needed for audit trail
GWP version	Recommended	AR5 or AR6 (Dcycle defaults to AR6 if not specified)
Supporting documentation	Optional	Stack monitoring reports, lab analyses, process engineer memos

Anything marked Required must be present before Dcycle can calculate. Recommended fields are not blocking but they make the record audit-ready. Optional fields are for your own traceability.

Where to find the emission factor

EU ETS Monitoring Plan — if your installation is in the ETS, your verified factors are already calculated and audited annually.
IPCC 2006 Guidelines (Vol. 3, Industrial Processes) — default Tier 1 factors per process and raw material.
Your process engineer or quality lab — composition-based factors (e.g. % CaO in clinker, carbon content of anodes).
Industry associations — Worldsteel, GCCA (cement), International Aluminium Institute, Fertilizers Europe publish sector-specific guidance.

Worked examples

Cement: calcination of clinker

Inputs to collect: tonnes of clinker produced, % CaO in clinker (from lab), % MgO in clinker.

Formula (IPCC Tier 2):

Emissions (t CO₂) = Clinker (t) × (CaO% × 0.785 + MgO% × 1.092)

The factors 0.785 and 1.092 convert calcium and magnesium oxide content back to the CO₂ that was released when the carbonates decomposed.

Example: 100,000 t of clinker at 65% CaO and 1.5% MgO → 100,000 × (0.65 × 0.785 + 0.015 × 1.092) = 52,664 t CO₂.

Enter in Dcycle as: activity data = 100,000 t clinker, emission factor = 0.527 t CO₂ / t clinker (your calculated value).

Aluminium: carbon anode consumption

Inputs to collect: tonnes of primary aluminium produced, net anode consumption rate (kg anode / t Al), sulphur content of anode, ash content.

Formula (IPCC Tier 2, prebake cells):

Emissions (t CO₂) = Aluminium (t) × NAC × (1 − S − Ash) × 44/12 / 1,000

NAC is net anode consumption in kg/t Al. The 44/12 converts carbon to CO₂.

Example: 50,000 t Al, NAC = 415 kg/t, S = 2%, Ash = 0.4% → 50,000 × 0.415 × (1 − 0.024) × 44/12 = 74,222 t CO₂.

Also: report PFCs (CF₄, C₂F₆) separately based on anode effect minutes per cell-day — your control room logs this.

Steel: blast furnace / basic oxygen furnace

Inputs to collect: tonnes of coke consumed in BF, tonnes of pig iron produced, tonnes of limestone/dolomite flux, electrode consumption in EAF.

Approach: carbon mass balance. Sum the carbon entering (coke, coal injection, limestone, electrodes) minus the carbon leaving in products (pig iron, slag) and convert the difference to CO₂ (× 44/12).

Easier path: use the Worldsteel CO₂ data collection methodology — it provides a standardised template and emission factors per process route. Dcycle accepts the output as a custom factor.

Glass: carbonate raw materials

Inputs to collect: tonnes of each carbonate raw material (soda ash Na₂CO₃, limestone CaCO₃, dolomite CaMg(CO₃)₂, feldspar, etc.) and the cullet ratio (recycled glass replaces virgin carbonate).

Formula (IPCC Tier 1):

Emissions (t CO₂) = Σ (raw material tonnes × emission factor × (1 − cullet ratio))

IPCC default emission factors:

Soda ash: 0.415 t CO₂ / t
Limestone: 0.440 t CO₂ / t
Dolomite: 0.477 t CO₂ / t

Chemicals: ammonia, nitric acid, adipic acid

Ammonia: CO₂ from steam reforming of natural gas. Factor: ~1.6–1.7 t CO₂ / t NH₃ (Tier 1).
Nitric acid: N₂O is a by-product. Factor depends heavily on whether you have abatement technology — from 9 kg N₂O / t HNO₃ (best available) to 12+ kg / t (uncontrolled). GWP of N₂O is 273 (AR6) — small mass, big impact.
Adipic acid: N₂O again, even more concentrated. Always disclose abatement status.

Refrigerant gases & SF₆ leakage

If your facility maintains its own large refrigeration plant or high-voltage switchgear and you don’t have invoices from a service company, you may need to estimate leakage directly. Use mass balance:

Leakage (kg) = Initial charge + Refills − Final charge − Recovered

Enter the leakage as the activity data and the GWP-weighted factor from the refrigerant or SF₆ as the emission factor.

How to enter process emissions in Dcycle

Process emissions always use a custom emission factor in Dcycle — there is no default library for industrial processes. The flow is:

Go to Data → Facilities and open the facility where the process happens.
Open the Process tab and click Add process emission.
Select the gas (CO₂, N₂O, PFC, SF₆, etc.) and the process category. (required)
Enter the activity data quantity and unit, plus the start and end dates of the period. (required)
In Emission factor, select Custom factor. Enter the numerical value, its unit (e.g. t CO₂ / t clinker), and the source of the factor for traceability. (required for the factor itself; source is recommended)
Save. Dcycle multiplies activity × factor, applies the GWP, and assigns the result to Scope 1.

If you can’t find or calculate a factor on your own, contact Dcycle support — we can help map your process to an IPCC or EU ETS default before you enter the record.

Best-practice checklist

Document the methodology (Tier 1, 2 or 3) for each process line
Keep lab analyses (oxide content, carbon content) for the reporting year
Separate process emissions from combustion — don’t double-count the kiln fuel
If you’re in the EU ETS, reuse the verified factors from your Monitoring Plan
Record GWP version used (AR5 or AR6) — Dcycle defaults to AR6
Re-validate factors annually — raw material composition drifts

What’s next

Scope 1 & 2 primary data: collection checklist — the main onboarding checklist
Understanding emission factors — how Dcycle picks factors and how to override them

If your process isn’t covered above, contact Dcycle support — we’ll help you find the right methodology and set up the custom factor.