Footprint per km and passenger

ℹ️ This rule comes from the futureco-data model.

Our objective is to estimate the footprint of a passenger on passenger ferries such as those linking mainland France to Corsica and England.

The ferry is often proposed as a serious alternative to the plane in terms of carbon footprint, but there was no estimate of its climate footprint per kilometre (neither ADEME in France, nor internationally, nor in the scientific literature) that takes into account not an average passenger, but the diversity of options for a ticket:

• passenger in car or not
• passengers in cabins, seats or on the ground
• the ship's leisure facilities: restaurant, bar, swimming pool, large corridors, etc.
• freight loaded in trucks
• % full on the boat
• speed
• etc

We know how much greenhouse gas (GHG) a given ferry emits: all we have to do is multiply its fuel consumption by the CO2e emission factor(s) of the fuel used. But the difficulty then lies in attributing a share of these GHGs to the passenger on foot, to the passenger alone in his or her car enjoying a VIP lounge, to the transport of goods, and so on.

The calculation principle adopted here is simple: we allocate a footprint according to the volume that the ticket purchased by the passenger and the consumption choices made on board occupy on the boat.

Here is the method note (~20 pages) which explains the problem we want to solve and the possibilities for making the calculation, but which remains theoretical.

Then, in concrete terms, you can take an interactive and complete look at the calculation of the dynamic emission factor just below ⬇️.

Finally, don't hesitate to make suggestions for modifying the model, either via a pull request on github or via a simple comment on this ticket.

In practice, we're doing this on the Mega Express Four type boat simply because we have fairly detailed plans of it. The work should be done for other ships in the future.

the Mega Express Four sailing on the Mediterranean](https://upload.wikimedia.org/wikipedia/commons/thumb/0/0e/02_Corsica_Ferries_Mega_Express_Four_(cropped\).jpg/640px-02_Corsica_Ferries_Mega_Express_Four_\(cropped\).jpg) More information on the Mega Express Four*

The calculation of the various surfaces is based on anSVG drawing on a plan of the ship's decks, which then allows us to deduce the volumes, and is therefore one of the keys to the calculation.

Limits of the calculation

A bias to be noted would be the inaccuracy of this plan of the ferry and the measurements made on it. However, it seems fairly reliable for an order of magnitude, which is our aim here.

Another bias is obviously the choice of what is counted as useful surface area and what is not. For example, we have excluded the open-air decks, except for the swimming pool and outdoor bars. Obviously, the calculation is only strictly applicable to this boat, but we have chosen to extrapolate it as a typical boat because we don't have the resources to model every commercial boat.

See also this ticket to read and contribute to the limits of the calculation.