Ship propulsion by renewable
energies available at sea:
Innovations for utilisation
of wind and waves
Dr. rer. nat. Jörg Sommer
Januar 2013
Preliminary remark 1
The next-but-one generation of vehicles will be
driven by hydrogen
 The BMW path: Hydrogen driven combustion motors
 The Mercedes-Benz path: Hydrogen – fuel cell – electric motor
 Prototype for ferries of the future: Alsterwasser
Alsterwasser: Ferry for 100
passengers, Hamburg 2008,
driven solely by hydrogen.
Preliminary remark 2
The hydrogen driven vehicles exist already – but
not the infrastructure:
We have to look for intermediate steps. One of
them could be
to produce hydrogen
aboard. This is the initial point of my further
considerations.
1. Sun alone isn‘t enough
Negative advertizing
A press release:
“The huge freighter capable of
carrying 6,400 automobiles is
equipped with 328 solar panels at
a cost of 150 million yen (1.68
million dollars), the officials said.
The solar power system can generate
40 kilowatts, which would initially
cover only 0.2 percent of the
ship's energy consumption for
propulsion, but company officials
said they hoped to raise the ratio.”
Auriga Leader, Japan 2008,
60,213 gross tons
33 PS or 32 hp for a superyacht
(31 m = 102 ft)
• Even a special design
for maximal use of
sun power results in
disappointing
performance.
• Despite the fact, that
this is one of the most
beautiful solar ships
ever built.
The Tûranor Planet Solar (loa 31m)
was entirely new designed for
maximal use of sun power, with 537
square meter solar panels.
Nevertheless she has to manage with
only 24 kW (32 hp).
2. Energy by sails isn‘t storable
• but they are the most effective
wind propulsors,
• especially the newly developed
wing sails.
BMW Oracle America's Cup boat
Relevation II
A wind turbine can do both:
1. Drive the boat or
2. produce storable
energy.
But for (1) you need a gear
and a screw, which
have friction- and
transmission losses,
and for (2) you need a
generator, a device to
store electrical energy,
and a motor to drive the
screw, also with
conversion losses.
3. The developement of mobile
wave energy converters is
insufficient
• Fins: Not a good
solution!
• Suntory mermaid II
reaches only
pedestrian mean
speed
• Orcelle: performance
not known, but most
likely insufficient.
Suntory
Mermaid 2
(Hiroshi
Terao)
Orcelle
(Wallenius Wilhelmsen)
Conclusion: All or none!
If you really want to promote the use of
renewable energies for ship propulsion,
you have to
• Use all sources available on sea,
• Make a new design,
• Take care of storing energy.
Primary energy and effective power
 facts & figures about sun-, wind-, and wave energy
 Example: Eco-Trimaran with realistic scenarios for method and location of
operation
Eco-Trimaran
•The broad roof
is covered with
solar cells.
•Wind turbine
of type „HRotor“. In a
newer version
the two rotors
are side by
side
(interlocking)
and not
twisted.
Technical data: LOA = 24.6 m, displacement: 61 m3
The floates can move
about their horizontal
cross axis (used for
wave power
conversion)
and about their
vertical axis
(necessary for
steering, avoiding of
torsional stress and
minimazation of drag)
The movements of the floats in the waves (upper
animation) are at first converted into hydraulic pressure
(lower animation) and then into electric power (not shown)
– the same principle as at Pelamis.
Pelamis is a stationary wave power
convertor. Several machines of this type
deliver electrical power since years.
The „Eco-Trimaran“ uses the same principle.
The only difference: His floats lie side by side and
not in a row.
The same principle of wave power
conversion may be realized by
other types of ships
Back to wind power:
How to combine the
benefits of a wind
turbine (energy
storage + ship
propulsion)
and wing sail (direct
propulsion without
storage- and
transformation
losses)?
Using a wind turbine as sail
Requirements:
• H-rotor (vertical axis) with 2 vertical blades (not twisted).
• Bracket for wind turbine.
• Step motor, which may turn the rotor together with its
bracket in any position of a 360° circle.
• Every blade is pivotable about its own longitudinal axis
by a step motor.
• Process computer to steer the step motors and a special
software.
Change of operation from wind turbine to
wingsail
1.
2.
Stop the wind turbine by its bracket
Turn the rotor together with its bracket in a position
which
a) is optimal for using the blades as sails and
b) minimizes shadowing of solar panels on the roof
3.
4.
Turn each blade in an optimal sailing position
Enlarge the area of the blades and give them a sail
profile.
How the latter is achieved is shown on the next frame:
From wing sail to blade and vice versa
hinge
State as wing sail
State as blade in a HRotor (wind turbine)
Topview
Some further benefits of this
construction
As sail:
• Fully automatic sail trimm
• Minimization of shadowing the solar panels
As wind turbine:
• Gain in efficiency by adaption of the blade angle to wind
direction (traditional H-rotor has fixed blades)
Sun: Global radiation and effective power
Primary energy
Northern scenario (North Sea)
E = 900 kWh
P1 = 0.10 kW
Sum of radiation
energy per year
and 1 m2
(horizontal plane)
P1 = E / 8760 h
Mean radiation
power per 1 m2
(8760 is the number
of hours per year)
Primary energy
E = 1800 kWh
P2 = 10.27 kW
P3 = 2.26 kW =
3.0 hp = 3.1 PS
P2 = P1 * 100 m2
Mean radiation
power arriving at
100 m2 solar cells
P3 = P2 * 0.22
Power output of 100
m2 solar cells. 0.22
is their efficiency
coefficient
Southern scenario (Mediterranean)
P1 = 0.20 kW
Effective power
P2 = 20.55 kW
Effective power
P3 = 4.52 kW =
6.1 hp = 6.2 PS
Wind: Speed and effective power
Primary energy
v1 = 8 m/sec.
mean wind speed
in a defined
hight, e.g. 50 m
(wind maps)
Primary energy
v1 = 7 m/sec
Northern scenario (North Sea)
V2 = 6.2 m/sec.
mean wind speed in hub
height of 9.5 m
v2 = v1*(9.5/50)0.12, where
0.12 is a roughness
coefficient for open sea
Effective power
P2 = 4.8 kW =
6.4 hp = 6.5 PS
P1 = 148 W
Wind power
per m2
P1 = 0.61 * v23
0.61 is half air
density
wind power of a wind
converter with an effective
area of 111m2 and degree of
efficiency of 0.29:
P2 = P1 * 111 * 0.29 /1000
Southern scenario (Mediterranean)
V2 = 5.7 m/sec.
P1 = 115 W
Effective power
P2 = 3.7 kW =
5.0 hp = 5.0 PS
Waves
Primary energy
T = 5.5 s
HS = 3.3 m
Significant wave hight
Hs and Period T (as
registrated by
detection buoys for
defined sea areas)
Northern scenario (North Sea)
P2 = 106 kW =
143 hp = 147 PS
P1 = 30 kW
Wave power per 1m
wave crest
P1= 0.5 * T * Hs2 (kW)
Effective power
power output of a wave line converter
with frontal width of 6.45 m, a degree
of efficiency of 0.7 (wave to wire) and
a free course relative to wave fronts:
reduction factor 0.7854
P2 = P1 * 6.45 *0.7* 0.7854 (kW)
Primary energy
T = 3.0 s
Hs = 1.29 m
Southern scenario (Mediterranean)
P1 = 5 kW
Effective power
P2 = 18 kW =
24 hp = 24 PS
Comparison: Waves are by fare the
best energy source!
Scenario
Source
North
South
best
unit
Sun
2,3
4,5
5,5
kW
Wind
4,8
3,7
6,7
kW
Waves
106,0
18,0
319,1
kW
113
26
331
kW
154
36
450
PS
Sum
But all things concidered: Is that enough for a super yacht (25 m = 81 ft)?
Critical considerations
Sum
113
26
331
kW
154
36
450
PS
This figures are Means.
There are days with higher energy input, but also days with
less.
We must also take into account the power consumption
aboard.
a southern scenario like the mediterranian is a very favored
region for superyachts
not every owner likes strong winds and high waves.
Is there annother source of energy?
The forth source: Stored energy
• The mooring times may be used for energy
storing.
• Especially super yachts have long mooring
times – in many cases 90% of the year!
• Hydrogen is proposed as storing medium; so
we take future proceedings into account.
• We have a bridge Technology to the next-butone generation of eco vessels.