What is well-to-tank, tank-to-wheel and well-to-wheel?

The terms "well-to-tank" (WTT) and "tank-to-wheel" (TTW) are used to describe different stages in the lifecycle of a vehicle's emissions, specifically in the context of evaluating the environmental impact of different transportation fuels and technologies.
​
These terms are often associated with greenhouse gas emissions, although they can be applied to other pollutants as well. Here's an explanation of each:

1. Well-to-Tank (WTT) Emissions:

• Well-to-tank emissions refer to the total greenhouse gas emissions associated with the production, processing, and distribution of a specific fuel type from the point of extraction or production (the "well") to the point where it is stored in the vehicle's fuel tank.

• WTT emissions include all the emissions generated during the entire supply chain of the fuel. This includes activities like extracting crude oil (for gasoline or diesel), refining the crude oil into fuel, transporting the fuel to distribution points, and storing it at gas stations.

• WTT emissions provide a comprehensive assessment of the environmental impact of a specific fuel type, taking into account the energy and emissions associated with its production and distribution.

2. Tank-to-Wheel (TTW) Emissions:

• Tank-to-wheel emissions, on the other hand, focus specifically on the emissions produced by a vehicle's engine while it is in operation and being driven on the road. These emissions are often measured in grams of CO2 equivalent per mile or kilometer.

• TTW emissions include all the pollutants released during the combustion of the fuel in the engine, such as carbon dioxide (CO2), nitrogen oxides (NOx), particulate matter (PM), and other harmful substances.

• TTW emissions provide insight into the immediate impact of a vehicle on the environment when it is in use and can vary depending on factors like vehicle efficiency, driving conditions, and maintenance.

3. "Well-to-Wheel" (WTW) is a comprehensive concept used to assess the total environmental impact of a specific transportation fuel or technology throughout its entire lifecycle, from the initial extraction or production of the energy source to its end use in a vehicle's wheels. WTW analysis provides a holistic view of the energy and emissions associated with a particular mode of transportation, taking into account all the stages involved.
​
In many instances (including our reports) the term CO2e is commonly presented as WTW. This shortened term includes a detailed evaluation that integrates both the Well-to-Tank (WTT) and Tank-to-Wheel (TTW) aspects of greenhouse gas emissions analysis.
​
For extra information about these terms, please contact sustainability@shypple.com