IEEE Electrification Magazine - September 2017 - 75

reduce emissions is the development of battery-based
propulsion systems with electric power distribution.
Unfortunately, the use of an electric power distribution
system, with power conversions from a diesel generator
and subsequent storage and retrieval from battery banks,
will inevitably result in power losses. However, the actual
operation of normal diesel-powered ships is seldom optimal, and only larger ocean-crossing vessels may hope to
operate their prime mover and support power systems in
an optimal fashion for prolonged periods of time. This
article presents the application of a serial-diesel-battery
hybrid power system installed onboard a Norwegian costal fisheries vessel, where the variation in power demand
allows the batteries to replace the traditional diesel
power used in fisheries. A power and propulsion system
design is presented as well as energy and time use data
for the vessel's operation during one calendar year. The
simple design of vessels, such as of the example vessels
in this article, allows battery hybrid power systems to
deliver energy savings due to the low-power demand of
the diesel engine operation at idle power used during the
operation of the fishing gear. The prime mover is
used to supply limited propulsion power, which is
mainly hydraulic and electric. The power system for the
example vessel is designed as a serial hybrid where the
diesel engine is exclusively used to supply electric
power to the batteries, which has the added benefit of
shielding the diesel engine from load variations on the
propeller. The hybrid battery power system is expected
to cut operating costs by minimizing fuel consumption
during fishing, reducing the use of engine lubricants,
diminishing maintenance costs by requiring fewer
engine-running hours, and increasing the lifetime of the
onboard diesel engine in calendar days due to decreased
running time.

These smaller vessels rely on delivering their catch
immediately after returning from the sea. The operational pattern is split between longer transits between
regions and relatively short and frequent trips out to the
sea. The duration each trip out is determined by the distance to the fishing ground and the gear type in use. The
typical transit time to the fishing ground is between
30 min and 2 h, and active fishing varies between 2 and
6 h, depending on catch quantity and gear type. The
most popular fishing gear types used in these vessels are
gillnets and jigs. Both are gear types that require little
energy to operate, as jigging is performed while the gear
is almost stationary, and gillnets are a passive gear type,
where the active phase for the vessel is limited to the
shooting and retrieval of the gear. Although transit is an
energy-intensive operational phase, the fishing phase
is characterized by low-energy demands, low speed, and
the use of deck machinery.
The typical machinery arrangement is a small diesel
engine with a direct propeller drive and electric power
and hydraulic power being delivered by the same
engine. The dominating gear used onboard these smaller vessels are gillnets and a jig. Mechanization and
power assistance for the fishing gear are powered by
hydraulics, which may also be used to power maneuvering thrusters. The dependence on the prime mover for
energy-to-vessel systems means that vessels have a

Norwegian Coastal Fisheries
The Norwegian fisheries fleet is organized into the oceangoing and coastal fleet groups. This organization is
enforced by zone limitations and quota distribution
between the different groups. The ocean-going fleet is
composed of a relatively small number of larger vessels,
whereas the coastal fleet is characterized by a large number of smaller vessels. The most common ship type in the
coastal fleet is the vessel smaller than 15 m (Figure 1).
These smaller vessels are based along the coast, where
rich fishery resources are found close to shore, enabling
them to spend 4-8 h at sea and deliver catch daily. The
fleet exhibits a regional mobility, which implies that vessels converge on seasonal fisheries in different regions
during different times of the year. There are roughly 5,000
registered and 4,000 active fishing vessels under 15 m.
These vessels catch approximately 200,000 t of fish each
year, making them a large and efficient fleet. The total diesel oil consumption of the smaller coastal fishing fleet
was 20,000 t in 2015.

Figure 1. Small costal fishing vessels at a harbor.
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