Are ferries green?


not by any means

What is Greenferries?

In an effort to reduce one's carbon footprint, many people are trying to fly as little as possible (the flygskam). Some may replace over-the-sea flights with ferry trips. However, it is very hard to get estimates on the environmental impact of ferries. There is a huge disparity between ships, and it is often that case that travelling with a ferry is worse than with a plane.

Who is behind this project?

We are a group (mostly myself, Adrien) of independent citizens (mostly french), and have no links to the transport industry nor to any government.

We are always looking for help, please reach out!(mailto:contact@greenferries.org).


The data shown here has no official value and may be erroneous.

Where does the data come from?'

The main data source is the THETIS-MRV report. The EU has a recent regulation that forces ships to install monitoring devices to track their emissions of CO₂ (among other things). The data is then reported and published as Open Data here. Thank you EU for that 👏

The links between ships and ferry companies and routes are manually filled by myself from information read on Wikipedia, the companies websites and also from the IMO.

The airports data come from ourairports.com, and the average emission rates for the other modes of transport come from this article by the ADEME, a french public institute for environmental matters.

How is the score computed?

There is a dedicated EcoScore documentation page

What computations are made on the raw data?

Apart from the EcoScore, we infer a few figures (total persons and freight transported, average speed etc..). You can find details about the formulas on this other documentation page.

Why is there such a tremendous impact difference between similar ships?'

Unfortunately, I have no idea. I am really looking for help to understand what could explain these differences.

Here are our uneducated guesses so far:

  • Ships that carry many cars but few people may perform much worse than ferries that carry lots of people and few cars (GreenFerries' only concern is about transporting people, not cargo, so we only display the 'per person' figure)
  • We did not understand what the data from THETIS means.
  • The monitorings are made with highly different methods from ship to ships.
  • The data is erroneous (monitoring or reporting problems)

What to do if you encounter an error or missing data?

Please let me know if you encounter an error on the website. As I have manually filled data, errors are bound to happen, and there is also a lot of data I am missing.

Why are there no ferry routes outside of the EU?

The only serious datasource I could find is THETIS-MRV report which concerns only ships crusing on EU seas.

If you know about Open Data that could be used for other parts of the world, please let us know

What are the approximations made?

GreenFerries aims to allow comparisons by order of magnitudes, not by decimals. In that idea (and because it's simpler) many shortcuts and approximations are made:

  • NOx and SOx emissions are completely ignored (because I could not find reliable data about it).
  • Emissions in the ports are not taken into account, only at sea (if I understood correctly the THETIS-MRV regulation)
  • distances between airports and between ports are computed as direct linear paths (with a +5% correction measure)
  • figures are rounded in various places

GreenFerries is a hobby project, all the data shown here has no official value. It is Open Source, so you can double check and modify it.

Ecoscore B
The Ecoscore compares average CO₂ emissions per passenger per km.
‟emits like 2.1 planes” means that the ferry emits more than twice what an average plane would on the same distance for one passenger.

Explore all 341 Ferries 🚢 Explore all 75 Companies 🏢

FAQ EcoScore API & Dumps ↗ EU 🇪🇺 Thetis-MRV Report ↗ GitHub ↗ Contact Discuss on gitter #greenferries ↗