Aarhus–Sjællands Odde, Hirtshals–Larvik and Hirtshals–Kristiansand. These three routes are on the list of the 50 most climate-intensive ferry routes in Europe. At the same time, Danish ferries overall rank tenth among Europe's largest CO₂-emitting ferries. And as a result, pollution with harmful sulfur oxides (SOx) is high in several Danish coastal cities.

Now showing a new analysis from Transport & Environment that the solution is right in front of us: a switch from diesel to electricity.

“Electrification of ferry routes is one of the fastest ways to reduce CO₂ emissions from maritime transport, while improving air quality for local citizens. The battery technology is ready. With the right policy measures and investments in charging infrastructure in ports, Denmark can accelerate the transition and make many ferry routes emission-free within the next decade,” says Katerina Davidova, advisor to the Green Transition Denmark.

Electrification is particularly promising on short ferry routes of less than 100 km, which make up a large part of European ferry traffic. Ferries are a central part of Europe’s transport network, carrying around 400 million passengers each year and connecting islands and coastal areas with the mainland. But most ferries still run on diesel engines, contributing to both climate change and air pollution. In ports such as Barcelona, ​​Dublin and Naples, ferries are responsible for more toxic air pollution than all the cars in the cities combined.

For Denmark, which has more than 60 ferry routes connecting the country's islands and creating connections to neighboring countries, electrification of ferries represents a great opportunity to reduce both air pollution and climate footprint. And it makes sense to consider it from the start. A Danish ferry lasts an average of 27 years. Several are already underway. In addition to a number of smaller ferries, Molslinjen is having three electric ferries built for routes on the Kattegat. Scandlines has an electric ferry sailing between Rødbyhavn from Lolland to Puttgarden. And the Øresundslinjen's ferries between Helsingør and Helsingborg are also powered by electricity.

High levels of sulfur oxides in Aarhus, Frederikshavn and Rønne

Diesel ferries emit pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx) and particulate matter. Electrification of ferries could significantly reduce air pollution in Danish port cities such as Rønne, Aarhus, Frederikshavn, Sjællands Odde and Spodsbjerg on Langeland, where ferries sail frequently and often close to residential areas. These five Danish ports with intensive ferry traffic have the highest concentrations of SOx emissions, often higher than emissions from road traffic in the cities in question.

Short and frequent ferry routes, common in the Baltic and North Seas, are particularly well suited to electrification because the ferries can charge quickly while passengers and vehicles are boarding. Denmark is also well-positioned thanks to strong renewable energy production, existing experience with electric ferries and a dense network of short ferry routes connecting islands such as Bornholm, Samsø and Ærø.

Political action is crucial to the pace of the transition. At the moment, the biggest obstacle to electrification is not batteries – it is the charging infrastructure in ports. However, the challenge is far from insurmountable. Most ports will only need relatively small chargers of less than 5 MW to support the operation of electric ferries.

In addition to investments in high-capacity charging infrastructure in Danish ports, a review of electricity tariffs and grid connection costs for ferry operators could create further incentives for electrification. Finally, using public procurement rules to prioritize zero-emission vessels when renewing the aging ferry fleet could accelerate the entire development.