The Clean energy for EU islands secretariat has published a new technical assistance report examining how to reduce emissions from ferry services connecting the Swedish islands of Hven, Visingsö, Vinön and Holmön with the mainland.
The study, available here: Decarbonisation of the ferry service for Hven, Visingsö, Vinön, and Holmön, provides a comprehensive assessment of maritime transport systems that are essential to daily life on these islands, where ferry routes typically cover distances of around 10 km in about 30 minutes and can reach up to 30 crossings per day.
As on many European islands, ferries are a vital lifeline for residents, businesses and visitors. At the same time, the report shows that maritime transport accounts for a significant share of local energy consumption, driven largely by the frequency of crossings and the reliance on fossil fuels.
A key finding of the study is the relatively low utilisation of existing ferry capacity. For example, average passenger occupancy rates range from around 4% to 15% depending on the route, highlighting a mismatch between service supply and actual demand. This suggests that aligning service frequency more closely with demand could significantly improve energy efficiency and reduce emissions per passenger.
The report also underscores the importance of adapting vessel size to real transport needs. Oversized vessels operating below capacity result in unnecessary fuel use, while smaller, lower-power ferries could deliver the same service more efficiently. In some cases, combining different vessel types—such as smaller ferries or on-demand taxi boats—could further optimise operations, particularly in low-demand periods.
Beyond operational improvements, the study explores technological pathways for full decarbonisation. It highlights that electric ferries are already a viable option for short-distance routes such as those analysed. A passenger ferry with a capacity of around 150 people, for instance, could meet demand even during peak summer periods with a limited number of daily trips.
Switching to electric propulsion could deliver substantial environmental benefits. According to the analysis, total energy consumption across the studied routes could be reduced by up to 80% compared to conventional diesel ferries, thanks to higher efficiency and appropriately sized vessels.
The report also considers how renewable energy can support this transition. Supplying electric ferries would require an estimated daily energy demand of around 8 MWh, which could be met through renewable sources such as solar photovoltaic installations combined with battery storage systems.
Finally, the study highlights that passenger and vehicle transport require different solutions. While electric ferries are well suited for passenger mobility, the transport of vehicles may be better served through dedicated vessels or alternative logistics concepts, including reservation-based systems or intermodal approaches.
Overall, the report provides practical and transferable recommendations for island communities across Europe. By combining smarter operations with clean propulsion technologies, the decarbonisation of ferry services can become both technically feasible and economically viable—supporting islands in their transition towards climate-neutral transport systems.