Charles Dubouix
How to measure freight emissions? (1/3): Homogeneity and data scope Is ?
- Carbon data is more available than ever.
- Nonetheless, shippers need to be careful in order to leverage this data properly.
- In particular, they should be cautious regarding:
- the greenhouse gases accounted (only CO2 or also methane and nitrous oxide?)
- the emission scope: considering only the combustion of the energy (TtW) or including the production and distribution of the energy (WtW) or including even a full Life-Cycle analysis
In the past few years, carbon emission data volume has skyrocketed and is much more available for shippers. Nevertheless, this proliferation hides some strong weaknesses and disparities.
In order to base one’s decarbonization strategy on reliable data, we need to understand the 4 main challenges that the freight carbon emission calculation is facing:
- Homogeneity and scope of data
- Data accuracy
- Data collecting
- Leveraging data with interpretable indicators
Which scope is accounted for?
Which greenhouse gases are included?
Although CO2 is responsible for more than 3/4 of the additional greenhouse effect, other greenhouse gases play a significant role, including methane and nitrous oxide.
When we measure only CO2 emissions we are talking about gCO2. To aggregate and weight the effects of other gases, a more complete measure is used: the CO2 equivalent that is therefore measured in gCO2eq or gCO2e.
Which emission scope is considered?
Similar to the way that companies differentiate their direct and indirect emissions through the concepts of Scope 1, 2 and 3, there are several ways to calculate the emissions of one transport and they are more or less restrictive:
- Well-to-Tank (WtT): accounts for the GHG emitted for the energy production and transportation
- Tank-to-Wheel (TtW): accounts for the GHG emitted by the freight mode itself, such as burning fuel to drive a truck.
- Well-to-Wheels (WtW): this is the aggregation of the two pre-existing segments (WtW = TtT+ TtW). This calculation takes into account the emissions from energy production and its combustion during transport.
- Its Tank-to-Wheels emissions (TtW) are null: an electric motor does not emit any GHGs
- Nevertheless, should we look at the electricity generation upstream and calculate the “well-to-wheel” emissions (WtW), it appears that this electric train is not carbon neutral. Especially if this electricity is produced in a country with a highly carbonized electricity mix - ie coal-fired power plants.
Can we expect any scope extension in the future?
With the current tools and methodologies available for the shippers, the Well-to-Wheel scope is the best approximation on the market.
However, this methodology is far from reflecting the global impact of freight in terms of GHG. In particular, the WtW methodology does not take into account:
- the construction of infrastructure and vehicles;
- their end-of-life;
- cargo-handling operations (airport and port operations for instance).
See below the average carbon footprint over the lifetime of a semi-trailer truck sold in 2030 in France| gCO2e/km. Source Carbone 4: Road transport: what alternative motorisations are sustainable for the climate?
