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:
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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
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Length, oa
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59,4 m.
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Length, bp
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57 m.
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Breadth, moulded
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12,8 m.
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Depth, moulded
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3,70 m.
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Gross tonnage
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996 t.
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Displacement
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933 t.
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Design, draught
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2,5 m.
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Design, deadweight
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187 t.
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Lightweight
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746 t.
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Deck space
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458 m2
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Deck capacity
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1,75 t/m2
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Service speed
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13,5 kn.
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Max speed
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14,2 kn.
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Capacity and crew
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Lane length vehicle deck
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145 m.
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Number of cars
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31
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Number of trucks/trailers
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5
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Number of passengers
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147/196
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Number of crew
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3/4
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Power and propulsion
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Main engines
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2x700 kW
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Thruster engines
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2x250 kW
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Nominal battery capacity
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4.3 MWh
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Available battery
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3.8-3.9 MWh
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Charging effect
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4 MW
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Classification and approvals
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Flag
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Denmark
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Approval basis
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DMA Notice D, RO Directive 2009/15EC, RO regulation (EC) 391/2009, SOLAS Chapter II-2, IMO MSC.1/Circ. 1455
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Classification society
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DNV GL
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Notations
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1A1 Car ferry B, Battery(Power), E0, Ice©, PWDK R3
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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:
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Departure Søby
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Arrival Fynshav
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Departure Fynshav
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Arrival Søby
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06:00
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07:00
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07:10
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08:05
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08:30
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09:30
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09:45
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10:40
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11:20
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12:20
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12:35
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13:30
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17:05
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18:05
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18:20
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19:15
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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%.
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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.