Method: TTW versus WTW
The Snapshot & Reflection 2025 uses two system boundaries side by side. Emissions reporting follows TTW: direct emissions within provincial boundaries. The reduction potential of solutions follows WTW: full chain emissions from source to use.
Download methodological appendix Download WTW and TTW comparison
Reading guide data and snapshot
Two data moments
The analysis is based on emissions data up to and including 2022 and 2023. Reporting data lags several years behind the publication date, so each edition uses the most recent fully available data years. This snapshot reflects on the Gelderland Climate Opportunities Map 2023-2024, which was based on data up to and including 2021.
The 2025 publication does not replace the earlier Climate Opportunities Map. The Gelderland Climate Opportunities Map 2023-2024 remains the planning and potential layer. The Snapshot & Reflection 2025 adds a progress layer: implementation, traction, remaining gap and attention points towards 2030.
Emissions accounting Tank-to-Wheel and Well-to-Wheel
For transport, energy and energy carriers, the system boundary determines which part of the emissions is included. TTW records direct emissions during use. WTW also includes upstream emissions, such as extraction, production, refining, transport, distribution and electricity generation.
Upstream emissions before use: extraction, production, refining, transport and distribution of the fuel up to the tank or charging point. For electricity, this refers to emissions from electricity generation.
Direct emissions from the use of fuel or energy in a vehicle, building, installation or process. In emissions reporting, this refers to direct emissions within provincial boundaries.
Total greenhouse gas emissions across the chain, from source to use. WTW is the sum of WTT and TTW and makes the effect of different solutions easier to compare.
Why two system boundaries are needed
Gelderland’s emissions trend is reported on the basis of TTW, because this method aligns with direct emissions within provincial boundaries and with the methodology of emissieregistratie.nl. The potential impact of solutions is calculated on the basis of WTW, because climate measures often affect the full energy chain.
This separation prevents methodological confusion. TTW shows what is emitted directly within Gelderland. WTW shows how much emissions a measure can actually avoid when the chain before use is also included.
Link with the GHG Protocol. Direct combustion falls under scope 1, purchased electricity under scope 2 and upstream chain emissions under scope 3. See also What is the GHG Protocol?.
The difference in Gelderland
WTW is typically around 5 to 10% higher than TTW, because upstream emissions are included. For Gelderland, the difference is approximately 9% in the estimate and approximately 5% in the ambitious scenario. The actual chain impact is therefore higher than the direct TTW figure indicates.
| Component | Method used | Function in the analysis |
|---|---|---|
| Historical emissions | TTW | Registration of direct emissions within provincial boundaries, based on emissieregistratie.nl. |
| Reduction potential of solutions | WTW | Comparable calculation of chain effects per measure, from source to use. |
| Progress towards 2030 | TTW plus WTW explanation | Implementation is assessed against registered emissions; solution effects are explained through chain impact. |
| Carbon storage | Separate reporting | CO2 storage is reported next to emissions reduction, so avoided emissions and stored carbon are not mixed. |
Avoiding double counting
The method does not double count potential and realised emission reductions. Only implemented measures count as solutions. Potentials remain scenario estimates for 2030 and are not added to registered emission reductions as if they had already been realised.
This keeps three layers visible: realised emissions development, the remaining implementation challenge and additional reduction or carbon storage potential.
Drawdown and Pareto
The Climate Opportunities Map uses Drawdown logic to order proven climate solutions by their potential for emissions reduction and carbon storage. For each solution, the possible contribution towards 2030 becomes visible.
A Pareto approach then helps prioritise the largest emission sources and the largest solution opportunities. In Gelderland, this puts emphasis on high-impact measures such as rooftop solar, zero-emission vehicles, onshore wind, ground-mounted solar and energy efficiency in industry.
Appendices and downloads
Traceable for each SMART solution
The assumptions, source references and calculations for each SMART solution are included in the methodological appendix. The additional spreadsheet compares WTW and TTW and makes the applied system boundary auditable.
Methodological appendix
Substantiation of potential per solution, including assumptions and source references.
WTW and TTW comparison
Spreadsheet comparing Well-to-Wheel and Tank-to-Wheel for the calculations used.
Further reading within the project family
Planning and potential layer with 30 SMART solutions, scenarios and reduction potential up to 2030.
Historical foundation and first sectoral exploration of climate solutions for Gelderland.
Exploration of carbon storage in agriculture, the living environment and circularity.
Energy, built environment, agriculture and land use, mobility and industry.
FAQ about TTW and WTW
What is the difference between TTW and WTW?
TTW stands for Tank-to-Wheel and includes direct emissions during use. WTW stands for Well-to-Wheel and includes both upstream emissions and direct emissions during use.
Why are emissions and solutions calculated differently?
Emissions reporting needs a clear territorial boundary and therefore uses TTW. Analysis of climate solutions requires insight into the full chain effect and therefore uses WTW.
How much higher is WTW than TTW in Gelderland?
WTW is typically around 5 to 10% higher than TTW. For Gelderland, the difference is approximately 9% in the estimate and approximately 5% in the ambitious scenario.
How is double counting prevented?
Historical emissions, implemented measures and future solution potential are kept separate. Potentials are not counted as realised reductions until measures have actually been implemented.