Fuel Combustion
Emissions API

We support 16 fuel types across four categories:

• Gaseous — Natural gas, LPG, CNG, biogas
• Liquid — Diesel, petrol, kerosene, fuel oil, red diesel (gas oil)
• Biofuel — Biodiesel (B100/FAME), HVO, bioethanol, wood logs, wood pellets
• Solid — Coal (industrial), coal (domestic)

Use the /v1/fuel/types endpoint to browse all supported fuels with their available units.

Available units vary by fuel type to match how fuel is commonly purchased and metered:

• Natural gas — kWh, therms, or m³
• Liquid fuels — litres or kWh
• LPG — litres, kWh, or kg
• Solid fuels — kg or kWh

The unit parameter is optional — if omitted, the API defaults to the most common unit for each fuel type (kWh for gas, litres for liquids, kg for solids).

Per GHG Protocol and DEFRA methodology, direct CO₂ from biofuel combustion is classified as biogenic and excluded from Scope 1 totals. This is because the carbon was recently absorbed from the atmosphere by the biomass.

The co2e figure for biofuels represents only CH₄ (methane) and N₂O (nitrous oxide) emissions from incomplete combustion. However, upstream (Well-to-Tank) emissions are still included by default and can be significant — for example, bioethanol WTT is 0.618 kgCO₂e/litre.

The response includes a biofuel_biogenic_carbon notice explaining this methodology whenever a biofuel is requested.

Many GHG reporting frameworks require individual gas species to be reported separately, not just the aggregated CO₂e total. This is particularly important for:

• National inventory reporting — requires individual gas quantities
• ISO 14064 compliance — specifies separate gas reporting
• CSRD ESRS E1 — expects granular emissions data

The aggregated CO₂e uses IPCC AR6 GWP100 values (CH₄ = 27.9, N₂O = 273) to convert all gases to a single carbon dioxide equivalent.

All factors are sourced from the UK Government GHG Conversion Factors 2025 (commonly known as DEFRA factors), published by the Department for Energy Security and Net Zero (DESNZ).

Direct combustion factors come from Table 1 (Fuels). Well-to-Tank factors come from Table 2 (WTT Fuels). All CO₂e values use IPCC AR6 GWP100 values.

Every response includes a source_trail referencing the specific DEFRA dataset and factor used.

Yes. DEFRA factors are the standard source for UK corporate reporting under Streamlined Energy and Carbon Reporting (SECR) and are widely used for EU CSRD compliance. Scope 1 fuel combustion is mandatory under:

• UK SECR — Streamlined Energy and Carbon Reporting
• EU CSRD — European Sustainability Reporting Standards (ESRS E1)
• California SB 253 — Climate Corporate Data Accountability Act
• CDP — Carbon Disclosure Project questionnaire

The individual gas breakdown (CO₂, CH₄, N₂O) and DEFRA source trail satisfy assurance provider requirements.

Absolutely — that's the idea. Together, our APIs cover the full GHG reporting stack:

• Fuel API — Scope 1 (this endpoint)
• Electricity API — Scope 2 (purchased electricity)
• Freight API — Scope 3 Category 4 & 9 (transport)
• Travel API — Scope 3 Category 6 (business travel)
• Hotel API — Scope 3 Category 6 (accommodation)

One provider, all three scopes. Complete corporate carbon footprint from a single API key.

Both have identical emission factors (2.5121 kgCO₂e/litre) since they're chemically the same fuel. Red diesel (gas oil) is rebated diesel used for off-road purposes — agriculture, construction, generators, and heating.

We include both as separate fuel types so your reports correctly label the fuel source. Red diesel use may have different tax and regulatory reporting requirements depending on your jurisdiction.