How to know passenger’s share of a ferry’s CO2 emissions? part II

As a rule of thumb, it can be said that the greenhouse gas emissions of passenger-car ferries are about half of the emissions of flying. However, the figures vary significantly, depending on how the shipping company divides the emissions between passengers and cargo.

When a ship carries both cargo and passengers at the same time, a decision must be made  which part of the transport vehicle’s emissions are calculated (allocated) to cargo and which part to passengers. Four years ago, I published a blog post titled “What are the emissions of ferry traffic for passengers?“, in which I explained that there are dozens of different justified ways to divide the emissions of passenger-car ferries between cargo and passengers.

In four years, the world has taken another step forward. New, more energy-efficient ships have entered service, but also the European Union has published principles on how ship emissions should be divided between passengers and cargo. In addition, all European shipping companies report their emissions and they are publicly available online (EMSA 2024).

According to the European Union, emissions are allocated between cargo and passengers (EU 2024): “For the split of the total fuel consumption and GHG emissions it is recommended to use the methodology defined in EN 16258190. EN 16258 allows the vessel’s total GHG to be split in a passenger and a freight element, in one of following two ways:

1. By mass

2. By area.”

Unfortunately, it is not publicly available knowledge which method the shipping companies have used. That is, there is no information whether the shipping companies use the same or different methods – most likely different methods. This means that the emissions they report are not comparable.

Figure 1. Carbon dioxide equivalent emissions of passenger car ferries departing from Finland in the EU database for 2024.

In Figure 1, I collected the carbon dioxide equivalent emissions of passenger car ferries departing from Finland for 2024 that were publicly reported and calculated how much of the share has been allocated to passengers and cargo.

The table revealed a lot of interesting information:

• The total emissions per nautical mile of passenger car ferries departing from Finland are roughly the same (column CO2eq emissions per distance). The total emissions of the Aurora Botnia, which only operates between Vaasa and Umeå, are about half of the emissions of other ships. On the other hand, the Aurora Botnia is smaller and carries less cargo and passengers on its voyages, so the emissions per passenger and cargo are in the same range as the others.

• The most important factor in determining how much emissions a passenger will incur is how the shipping company divides its emissions between passengers and cargo (column pax share of emissions). This depends on which of the calculation methods described above it uses and, of course, on how many passengers and how much cargo it actually carries per year.

• The most dramatic differences are seen in traffic between Finland (Turku/Naantali) and Sweden (Stockholm/Kapellskär), where Baltic Princess reports almost 90% of its emissions to passengers, Viking Grace and Glory 20%, and Finnsirius and Finncanopus only about 5%. This means that according to this official database, the emissions of those travelling on Baltic Princess are almost ten times higher, while the ship itself only emits less than twice as much as its competitors.

• Finnair reports that its emissions per passenger and flight kilometre are around 125 g CO2. According to Figure 1, emissions from shipping vary from 80 g CO2eq/passenger to 800 g CO2eq/passenger. However, the average value is in the same range as in air transport – and using Viking Line’s coefficients, it drops to less than half.

• Based on this, we could use the figure as a rough guide that emissions per passenger on passenger car ferries are about half of the emissions from flying (note! In Figure 1, emissions are per nautical mile, i.e. 1.852 km).

However, these emissions are still just the beginning. International emissions trading system and regulations are making ship emissions increasingly expensive, so it is expected that more and more energy-efficient ships will enter maritime traffic between Finland and foreign countries, using new emission-free fuels. These figures in this blog will also soon become outdated.

Sources:

EMSA (2024) MRV – Thetis. https://mrv.emsa.europa.eu/#public/emission-report

EU (2024) The EU ETS and MRV Maritime General guidance for shipping companies Guidance document No. 1, Updated Version, 5 November 2024. https://climate.ec.europa.eu/document/download/31875b4f-39b9-4cde-a4e2-fbb8f65ee703_en?filename=policy_transport_shipping_gd1_maritime_en.pdf