IEEE Electrification Magazine - September 2017 - 17

DNV GL Battery Ship Classification Rules
A ship that is going to be classed by DNV GL must be
built according to DNV GL class rules. The DNV GL
class rules are based on the International Convention
for the Safety of Life at Sea (SOLAS). In addition to the
SOLAS requirements, the electrical system onboard
a ship must be based on applicable standards for
ships as issued by the International Electrotechnical

Transit > 10 kn
15%

Harbor
26%

Transit
7-10 kn 7%
Transit
< 7 kn 5%

DP
19%

Standby
28%

Percentage of Conventional

Figure 11. The Viking Lady's operational profile.

120
100
80
60
40
20
0

Fuel

CH4

NOx
Conventional

Hybrid

(a)
Percentage of Conventional

DNV GL's in-house modeling and simulation platform Complex Ship Systems Modeling and Simulation
(COSSMOS) has also played a key role in the project
(Figure 10). It was instrumental in performing earlystage feasibility and performance analyses of the
integrated hybrid system. Advanced COSSMOS simulations later helped identify promising power management strategies to maximize the energy gains
while ensuring the ship's safety and operational capabilities. The same simulation models have since
been used to quantify savings and further optimize
the use of the battery hybrid power system. Combining real-life measurements with advanced simulation
models has proven to be a very powerful way of gaining a deeper understanding of maritime battery hybrid
propulsion systems.
The battery hybrid installation on the Viking Lady
was extensively tested during sea trials in 2014. Significant fuel savings and emissions reductions were
found to be achieved with battery hybrid operation
but with appropriate battery sizing and implementation of optimal power-management strategies re quired. Calibrated COSSMOS simulations were used to
extrapolate the measurement results to further operational strategies that for different reasons could not be
tested in practice.
An annualized projection of the results for the full
operational profile of the Viking Lady (Figures 11 and 12)
shows that a 10-15% reduction in fuel consumption, a
25% reduction in NOX emissions, and a 30% reduction
in GHG emissions can be realized in practice, with significant improvements in DP operations in particular.
The savings are primarily achieved through reducing
the number of running generator sets in the DP and
transit mode. It is important to emphasize that the
potential savings will vary from one ship design to
another, even within the offshore segment, depending
on the generator type and size, battery size, operational profile, power management strategies, and so forth.
The following activities are currently ongoing in the
fourth phase of the FellowSHIP project:
xx
hybrid control strategy optimization and COSSMOS
power system simulations
xx
ship simulations to investigate improved dynamic
and failure handling capabilities
xx
computational fluid dynamics simulations to optimize transit operation
xx
battery degradation-state of health (SOH) monitoring
xx
maintenance data analysis.
DNV GL invests 5% of its revenue in research and innovation every year-investments leading to technology
development and better services. FellowSHIP is one example of joint research projects led by DNV GL aiming to
improve the safety and sustainability of the maritime
industry. The FellowSHIP project is being cofunded by the
Research Council of Norway.

120
100
80
60
40
20
0

Fuel

Conventional

NOx
Hybrid Two Gen

CH4
Hybrid One Gen

(b)
Figure 12. The Viking Lady sea trial measurement results under
(a) DP calm-weather conditions and (b) DP rough-weather conditions.
Gen: generator.

IEEE Elec trific ation Magazine / S EP T EM BE R 2 0 1 7

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