CO₂ Emissions Calculator
The Ionect CO2 emissions calculator estimates the carbon dioxide emissions of any fuel, electricity grid, or industrial process. It uses default emission factors from the IPCC 2006 Guidelines, IEA, Ember, and DEFRA, and produces engineering-grade order-of-magnitude estimates suitable for early-stage scoping, decarbonization screening, and academic work.
Trusted data sources: IPCC 2006 Guidelines, IEA, Ember, DEFRA/DESNZ, GCCA, IRENA, EEA.
How the calculator works
Fuel and energy
- Energy content: 36 GJ NCV
Assumptions and sources
E_CO₂ [kg] = energy [GJ] × EF_combustion [kg CO₂/GJ NCV]- Natural gas — combustion EF56.1 kg CO₂/GJ NCVIPCC 2006 Vol.2 Table 2.2
- Net calorific value47.5 MJ/kgIPCC 2006 / fuel database
- NCV (volumetric)36 MJ/Nm³IPCC 2006 / fuel database
Methodology and assumptions
Fuel combustion uses the IPCC 2006 Tier 1 default emission factors (Volume 2, Chapter 2, Table 2.2), expressed in kg CO₂ per GJ on a Net Calorific Value (NCV) basis. The tool multiplies the energy content of the fuel by the combustion factor. Quantities entered as mass or volume are converted using the fuel's NCV and density.
Well-to-tank (WTT) upstream emissions are based on the DEFRA/DESNZ 2024 GHG Conversion Factors and the IEA Life Cycle Upstream Emission Factors Database 2024. They cover extraction, processing, and transport of the fuel.
Electricity uses location-based grid emission factors from Ember 2024 and the EEA 2024 estimates, expressed in g CO₂ per kWh. The market-based mode lets users override with a custom value such as a PPA. The lifecycle option adds typical mid-point offsets for fossil generation.
Industrial processes use sector-average intensities from IEA tracker pages, GCCA GNR 2022, IRENA 2024, and OECD Climate Club 2025. The tool reports total emissions, the specific intensity per tonne of product, and where applicable a best-in-class benchmark and a near-zero threshold.
Hydrogen pathways follow the IEA Global Hydrogen Review 2024. Grid electrolysis is computed live as 52 kWh/kg H₂ × grid factor + 1.5 kg CO₂/kg H₂ embedded electrolyser intensity.
Carbon price. The EU ETS exposure uses a default of €75 per tonne CO₂, adjustable in the results card.
Emission factors and sources
- IPCC 2006 Guidelines for National Greenhouse Gas Inventories, Volume 2: Energy, Chapter 2 (Table 2.2).
- DEFRA/DESNZ UK Government GHG Conversion Factors for Company Reporting 2024.
- IEA Emissions Factors 2025.
- IEA Life Cycle Upstream Emission Factors Database 2024.
- IEA Global Hydrogen Review 2024.
- Ember Global Electricity Review 2025 and European Electricity Review 2025.
- EEA, Greenhouse gas emission intensity of electricity generation in Europe (2024 early estimates).
- GCCA Getting the Numbers Right (GNR) database, 2022 data.
- IEA Cement, Steel, Aluminium, and Chemicals tracker pages 2024.
- IRENA Decarbonising hard-to-abate sectors with renewables, 2024.
- OECD Carbon intensity metrics in steel and cement (Climate Club members), 2025.
- European Commission CBAM and EU ETS Phase 4 documentation; ICE EUA Dec futures and EEX auctions for EUA pricing.
Frequently asked questions
What is a CO₂ emissions calculator?
A CO₂ emissions calculator is a tool that estimates the carbon dioxide released by combusting a fuel, consuming electricity, or running an industrial process. It multiplies an activity quantity by a published emission factor.
How is CO₂ from fuel combustion calculated?
The energy content of the fuel (in GJ, using its Net Calorific Value) is multiplied by an emission factor in kg CO₂ per GJ. Default factors come from the IPCC 2006 Guidelines, Volume 2, Table 2.2.
What is the difference between Scope 1, Scope 2, and Scope 3?
Scope 1 covers direct emissions from sources owned or controlled by the organization. Scope 2 covers indirect emissions from purchased electricity, heat, or steam. Scope 3 covers all other indirect emissions across the value chain, including upstream fuel production (well-to-tank) and downstream product use.
What is the difference between LHV (or NCV) and HHV (or GCV)?
The Lower or Net Heating Value excludes the latent heat of water vapour formed during combustion. The Higher or Gross Heating Value includes it. NCV is the standard basis for IPCC emission factors. For natural gas, NCV is roughly 10 percent lower than GCV; for liquid fuels, around 5 percent lower.
What is the carbon intensity of natural gas?
Natural gas emits about 56.1 kg CO₂ per GJ NCV from combustion, or roughly 2.0 kg CO₂ per Nm³. Adding upstream methane leakage and processing, the well-to-combustion factor is typically 67 to 70 kg CO₂e per GJ.
How much CO₂ does a tonne of cement emit?
Global average emissions are around 580 kg CO₂ per tonne of cementitious product (2022 data, GCCA). Pure Portland clinker is higher, at about 860 kg CO₂ per tonne. About 60 percent of cement emissions come from limestone calcination, not fuel combustion.
What are the emissions of grey, blue, and green hydrogen?
Grey hydrogen from natural gas emits 10 to 12 kg CO₂e per kg H₂. Blue hydrogen with 90+ percent carbon capture can reach 1 to 4 kg CO₂e per kg H₂. Green hydrogen from renewable electrolysis is typically 0.4 to 2.7 kg CO₂e per kg H₂, depending on the electricity source.
What is the carbon intensity of EU electricity?
The EU-27 average was about 213 gCO₂ per kWh in 2024 (Ember). Country values range from below 50 gCO₂/kWh in France, Norway, and Sweden, to over 600 gCO₂/kWh in Poland.
What is the global average grid emission factor?
In 2024, the global average was about 473 gCO₂ per kWh (Ember Global Electricity Review 2025). This has been declining at roughly 1 to 3 percent per year due to the build-out of renewables.
How accurate is this calculator?
The tool produces order-of-magnitude estimates using internationally-recognized default emission factors. Actual emissions can vary by ±10 to ±30 percent depending on fuel composition, equipment efficiency, methane leakage, and process specifics. For regulatory inventories or LCA studies, site-specific data and certified methods should be used.
Does the calculator account for methane leakage?
The 'combustion only' mode does not. The 'Combustion + upstream (Scope 1 + WTT)' toggle includes typical upstream methane and CO₂ emissions based on DEFRA 2024 and IEA Upstream Emissions Factors data, with values shown explicitly.
What is the EU ETS price used?
The default is €75 per tonne CO₂, reflecting EU Allowance prices in early-to-mid 2026. Users can override this with their own carbon price assumption.
The calculator uses default emission factors from internationally recognized sources. Actual emissions depend on fuel composition, equipment efficiency, process configuration, and upstream methane leakage. Use this tool for screening and scoping, not for regulatory reporting or verified GHG inventories. Ionect can support more detailed assessments through techno-economic studies and conceptual engineering.