Well-to-tank emissions refer to the Greenhouse Gas emissions released during the sourcing, processing, storage, and delivery of fuel used by vehicles in the supply chain. This fuel must be extracted from the ground, transported to the oil refineries and then distributed to refueling stations all before it fills the tanks of vehicles (hence well-to-tank).

Emissions generated during this stage can contribute heavily to your overall carbon footprint. Let's say, for example, that your last-mile delivery provider only uses electric vehicles. While your vehicles won't release any emissions, fuel is still required to generate and distribute power to the stations where you charge your vehicles, and that process generates emissions.

On the other side, tank-to-wheel emissions refer to any emissions produced by vehicles used in the supply chain. This includes any activity from the moment that the vehicle is filled with fuel up until it returns to the original location.

For electric vehicles, the tank-to-wheel emissions are always 0, since no fuel is actually used by the vehicle itself, so if your last-mile delivery company uses EVs, then you’re already on the right track.

As a business, tracking tank-to-wheel emissions will help you measure the impact of changes to vehicles or fuel used by yourself or other companies in your supply chain. While this is a great starting point when calculating your carbon footprint, it's necessary to consider well-to-tank emissions to get an accurate measurement.

Measuring emissions across both stages (also known as well-to-wheel) gives us the most accurate representation of our carbon footprint. By doing this, we can make better choices at each stage of the supply chain and ultimately move closer to our sustainability goals.