IEEE Electrification Magazine - September 2017 - 12

Energy Storage on Ships

To facilitate harbor
and near-shore
operation with
zero emissions,
plug-in hybrid
power systems
are expected to
become the
preferred solution.

January 2017, there were eight offshore ships in the DNV GL class
under construction or sailing with
large lithium-ion (Li-ion) battery
systems installed.
For the ferry segment, mediumand long-range hybrid designs
have proven to be attractive in addition to full electric shorter-range
ferries. The world's first large-size
all-electric battery-powered car
ferry, the Ampere, came into operation in January 2015 (Figure 2). This
120-car, 350-passenger ferry is
equipped with a 1-MWh battery
system. The zero-emission ferry
utilizes quick 10-min charging that
takes place between each 20-min crossing and a full
charge overnight. Subsequently, the Norwegian government encouraged all new invitations for ferry tenders in
Norwegian waters to request zero- or low-emission propulsion technology. Several new all-electric or battery
hybrid ferry projects are currently being designed or are
under construction.
For bigger passenger vessels, several ships have been
retrofitted with large battery systems in a hybrid configuration. One of the first installations was the 2.7-MWh
battery system installed on Scandlines' Prinsesse Benedicte, operating between Denmark and Germany. Another big project is the HH ferry group's ships Tycho Brahe
and Aurora, sailing between Sweden and Denmark, being
upgraded this year with 4.2-MWh battery systems. Several new building projects involving battery hybrid propulsion also have been announced recently, such as
Hurtigrutens' two polar expedition ships, to be delivered
in 2018-2019. Also worth mentioning is Color Lines'
2,000-passenger ferry, described as the world's largest
hybrid ferry, which will operate
between Sandefjord, Norway, and
Strömstad, Sweden.
Energy storage systems have so
far seen a small penetration into
the cargo ship segment, but hybrid
crane operation with regenerative
braking is one of many possibilities.
Grieg Star has installed a 67-kWh
battery system on the Star Laguna,
with expectations of significant
energy- efficiency improvements
and reduced emissions during
port operations.
Considering future regulations
and expected fuel cost trends, it is
very likely that the maritime industry
in the future will utilize a more
Figure 2. The Ampere, the world's first fully electric car ferry. (Photo courtesy of DNV GL.)
diverse fuel mix, where liquid natural
A 2011 study by DNV GL demonstrated that energy storage technologies represent a substantial
potential for improving both fuel
economy and reducing emissions in
the maritime industry. One of the
conclusions of the study was that
ship types with large load variations
on the main or auxiliary machinery,
high redundancy requirements,
and/or low utilization of engines for
long periods of time are typically
well suited for hybrid power systems. This includes offshore ships,
drill ships, shuttle tankers, icebreakers, and tugs. A simple mathematical model was developed to evaluate the potential savings
and costs associated with the introduction of hybrid power-train systems and energy storage devices in certain
types of vessels. The model considered the operational
profile and included the expected power demand and
power variations during operation. The study concluded
that overall fuel savings of 10-25% could be realized,
although this would be heavily dependent on the operational profile and power system configuration. To facilitate
harbor and near-shore operation with zero emissions,
plug-in hybrid power systems are expected to become the
preferred solution.
In terms of cost-effectiveness and payback times,
there will naturally be large variations from project to
project because of such things as varying integration
costs, operational profiles, and fuel prices. However, the
study shows that, with fuel savings in excess of 10%, a
return on investment within five years is fully possible
when utilizing funding schemes like the Norwegian
NOX Fund (NHO 2017) and/or Enova (Enova 2017). As of

I E E E E l e c t r i f i c ati o n M agaz ine / SEPTEMBER 2017

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2017