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Idea

The newbuilding of smaller ferries in Denmark has for numerous decades not been focusing on energy consumption as fuel cost only accounted for a relatively small part of total cost. Instead emphasis has been on newbuilding price and high capacity. However, the sudden rise of oil price and the increased focus on environmental concerns have put stress to traditional designs making even recent ones obsolete, in a sense.

Returning to ferry designs of the nineteen forties and fifties much more fuel efficient designs can be found. Designs then were slimmer and had lower water resistance in channels and confined waters with restricted depths. Combined with modern light weight building materials and computer fluid dynamics design solutions it is possible to reduce the energy consumption of the typical smaller island or local ferry dramatically. The savings will result in better environmental performance and better economy in total but could also be exchanged into higher service speeds in this ferry segment which has prevailing speeds of 8-12 knots.

Profile starboardAn energy optimized design combined with the relatively short operating distance for most of these ferries then brings battery operation within a realistic scope. Hybrid solutions with diesel or gas engines producing electricity to batteries at optimal engine loads and with electrical propulsion are becoming more frequent in coastal ship types these days ranging from tugboats over offshore supply vessels to smaller and larger ferries. In Denmark e.g. Svitzer, A2Sea, Esvagt, Scandlines and Danske Faerger are building or have planned to build ships with hybrid solutions. However the ambition of the green ferry vision is to leap to the next level skipping the hybrid solution and all fossil fuels by using energy stored on batteries only, charged when at berth with electricity produced by wind turbines.

The zero emission ferry will allow for almost no engine room, total redundancy, high fire safety, higher speed, little maintenance and less crew requirements making its operation extremely cost efficient. With the use of light weight carbon composite materials and innovative technology the local shipyards regain a competitive advantage. At the same time the involved professional partners acquire a unique knowhow into the future of electrically powered shortsea ships. This in turn will help preserve production jobs and create new knowledge based jobs in the local maritime sector.

For the Island of Aeroe the zero emission ferries would mean a more scalable ferry operation using four smaller ferries of three crewmembers instead of three larger ferries with five crewmembers. Today demand in summer time is double the winter demand although capacity can only be scaled around ten percent as all hours must be serviced. It is possible that the ferries could be designed for down to two crewmembers for off peak departures with low passenger demand. With low energy cost and low crew cost this could
make even these departures profitable giving islanders a better infrastructure and more flexibility to travel.