Curious to know how it is possible to operate a car- and passenger ferry across a distance of 22 nautical miles on 100% electricity?

The E-ferry, “Ellen” has since mid August 2019 been doing this 3-5 times a day, every day of the week on the route from Søby to Fynshav in the Danish part of the Baltic Sea. The E-ferry is a Horizon 2020 funded project aiming to design, build and demonstrate a 100% electric, emission free, medium sized ferry for passengers and cars, trucks and cargo on medium range connections (up to 22 nautical miles). The project is coming to its end on June 1, and the E-ferry’s technical, economical, environmental and societal impact is currently being evaluated as part of the project. Alongside the evaluation for the EU Commission, the E-ferry consortium will also prepare an executive summary of the evaluation, which will be available to all interested parties. If you are interested in receiving this evaluation package, you can contact/sign up here and you will receive the executive summary and evaluation package in June 2020.

Meanwhile, here are some basic facts:

  • Main particulars

The E-ferry, named “Ellen” is a small-medium sized car- and passenger ferry, designed to meet the needs for transportation in island communities and coastal zones. The ferry can transport 31 cars or 4-5 trucks, and between 147 (winter) and 196 (summer) passengers.

Principal dimensions
Length, oa59,4 m.
Length, bp57 m.
Breadth, moulded12,8 m.
Depth, moulded3,70 m.
Gross tonnage996 t.
Displacement933 t.
Design, draught2,5 m.
Design, deadweight187 t.
Lightweight746 t.
Deck space458 m2
Deck capacity1,75 t/m2
Service speed13,5 kn.
Max speed14,2 kn.
Capacity and crew
Lane length vehicle deck145 m.
Number of cars31
Number of trucks/trailers5
Number of passengers147/196
Number of crew3/4
Power and propulsion
Main engines2×700 kW
Thruster engines2×250 kW
Nominal battery capacity4.3 MWh
Available battery3.8-3.9 MWh
Charging effect4 MW
Classification and approvals
Approval basisDMA Notice D, RO Directive 2009/15EC, RO regulation (EC) 391/2009, SOLAS Chapter II-2, IMO MSC.1/Circ. 1455
Classification societyDNV GL
Notations1A1 Car ferry B, Battery(Power), E0, Ice©, PWDK R3
  • Operation/demonstration area.

The E-ferry Ellen is being demonstrated in ordinary operation by the public ferry-company Aeroe-ferries on the route from Søby on the island of Ærø, to Fynshav on the island of Als, in the southern part of Denmark. The E-ferry is also designed and approved for operating between Søby and Faaborg on Fyn.

The E-ferry has since august 2019 been tested with different operation schedules and different charge- and harbor times, with between 3-5 daily trips. The current sailing schedule, with 5 trips, is as follows:

Departure SøbyArrival FynshavDeparture FynshavArrival Søby
  • How does it work?

The E-ferry Ellen is charged up to 3.8 MWh during the night stay in Søby. On the return trip between Søby-Fynshav-Søby, the E-ferry Ellen’s propulsion consumes between 1400-1700 kWh of energy from the batteries (depending on various conditions such as weather, routing, load) to cover the 22 nautical miles in just under 2 hours (excluding the time for a short stay in Fynshav to unload and load cars and passengers).

Upon each return to the charging harbor Søby, Ellen’s crew connects the charger, which can charge with an effect of up to 4 MW, depending on how far the batteries are already charged. As a rule-of-thumb, the general pattern is that Ellen’s battery rooms will be charged at full effect (just under 2 MW each) until the batteries have reached a capacity of around 1600 kWh, after which the charging effect will gradually ramp down.

The operation schedule allows for charging breaks between 15-40 minutes, so it is not after each break that the E-ferry Ellen leaves the charging harbor fully recharged and the overall charged capacity will thus slowly reduce over the day. At the end of the day, when the E-ferry Ellen has completed her last trip, her battery capacity is reduced to around 30%.

  • How does the crew make sure that they do not run out of energy in the middle of the trip?

There are several safety measures in place to ensure that this will not happen. Firstly, the whole system is redundant, with two separate battery rooms, each in themselves consisting of 10 separate strings of batteries, each at a nominal capacity of 215 kWh. If one or two of these strings are emptied or stop working for some other reason, the E-ferry can in principle continue its operation. If a whole battery room fails, the E-ferry can sail back to harbor on remaining capacity. Secondly, each battery room has at any given time a reserve of almost 400 kWh for emergency purposes, each of which will also allow the E-ferry to sail back to harbor (at reduced speed) in case of an emergency. To ensure that the E-ferry batteries last as long as possible, however, the E-ferry is only rarely operating below 30% of its battery capacity, so in fact there is plenty of reserve capacity onboard, for every eventuality. The reserve capacity is used in lieu of a back-up diesel generator, so even the E-ferry back-up systems are fully electric and hence emission free.

Find more info here