TURNING THE TIDES ON EFFICIENT ENERGY MANAGEMENT: THE HORIZONTAL AXIS TIDAL TURBINE

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24 Οκτ 2013 (πριν από 3 χρόνια και 8 μήνες)

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Session A6

2103

University of Pittsburgh

Swanson School of Engineering

February 8, 2012

1

TURNING THE TIDES ON EFFICIENT ENERGY MANAGEMENT: THE
HORIZONTAL AXIS TIDAL TURBINE


Ryan Dolan

(
rjd37@pitt.edu
),
Daniel Kueffner (dsk27@pitt.edu
)


Abstract

This paper will clearly describe and evaluate the
horizontal axis tidal turbines and the energy benefits that
come along with them. This innovative method of using
specific tidal turbines on river floors (or other current
occupied bodies of water) presents

a resourceful form of
energy management. This paper will specifically analyze the
methods of increasing the efficiency of such turbines by
studying wake effects and adaptive blades. Current research
is being done on blade technologies for these horizonta
l axis
tidal turbines. This research will be assessed in the
following paper, along with the value of such machines
and
the ethical standpoints behind the environmental impacts of
these turbines. Ethical positions such as cost and
environmental effects wil
l be linked into its overall
efficiency. This machinery could establish a precedent to
society to look at the world around us and try to use our
tools to our own advantage.



Key Words

Dynamic Fluid Energy, Energy Management,
Hydroelectric Power, Computat
ional Fluid Dynamics,
Renewable Energy, Tidal Turbine.

T
HE
T
IDAL
T
URBINE

The vast and powerful oceans of the world have been
dominating over 70% of the earth for many years now. Until
recently, however, there has been little real success in
efficiently co
nverting this power and using it to alleviate the
increasing energy demands of modern society [1]. The
emerging technologies of tidal turbines allow for a strong
and efficient extraction of energy if applied suitably.
Throughout the paper, the efficiency

of a horizontal axis
tidal turbine (HATT) will be specifically analyzed. The
term horizontal axis tidal turbine simply refers to the
turbines whose
blades spin

orthogonally to the water’s
surface.


FIGURE 1

A

H
ORIZONTAL
A
XIS
T
IDAL
T
URBINE
(
LEFT
)

AND A
HATT

F
ARM
(
RIGHT
)

[2
]

The HATT’s counterpart, the Vertical Axis Tidal
Turbine (VATT), is hardly ever used due to the superiority
of the HATT. Therefore, solely the horizontal axis tidal
turbine will be analyzed because it is accepted as the more
effective

and efficient type of tidal turbine.

E
FFICIENCY IN
T
URBINE
T
ECHNOLOGY

Efficiency is one of the most important aspects when
desi
gning and planning for a tidal turbine
. While being a
heavy topic, greater efficiency is completely necessary for
tidal turbin
es to compete effectively with other forms of
energy management. Whether analyzing individual
horizontal axis tidal turbines or horizontal axis tidal tu
rbine
farms, efficiency will be

main concern brought forth
throughout the paper. By studying the wake
effects
produced by HATTs and examining optimal blade
geometries for individual turbines,
numerous
achievements
in the efficiency of these turbines can be attained.

S
TUDYING
W
AKE
E
FFECTS

In essence, a wake in fluid mechanics can be described as a
region o
f disturbed flow caused by a solid body moving
through a fluid. Wakes create different flow patterns and
can definitely affect the efficiency of a HATT depending on
the particular strength of a wake. While not necessarily
chaotic, the wake effects create
d by a HATT are extremely
difficult to analyze without the aid of computational devices.
Generally, computational fluid dynamics (CFD) is
introduced when dealing with disturbed flows such as the
ones caused by HATTs. The use of CFD allows for an in
-
depth

view at how one HATT can affect another one
on

a
HATT
farm. The values for the center
line velocity deficit
found using

a CFD program called “3D
-
NS” can be plotted
against the diameter of a turbine

in a computer trial
. This
can show an overlaid
interaction between two HATTs.
When two HATTs are aligned in a tandem arrangement, the
wake produced by the upstream turbine will interfere with
the flow captured by the downstream turbine. This will
reduce the amount of power produced

by the downstream
turbine [1][3
].

Therefore, choosing to align these tidal turbines in front
of each other can only reduce the efficiency of a turbine
farm. Instead, it is more efficient to align each individual
HATT next to each other. This will minimize the intrusion
of

a turbine’
s wake on a neighboring turbine and
consequently improve its power production.




Ryan Dolan



Daniel Kueffner

2

B
LADE
G
EOMETRY

Perhaps one of the most important topics when analyzing the
efficiency of a horizontal axis tidal turbine is the topic of
how the blades on the turbine

are structured. Through
physical tests and computational trials, we can examine the
optimal geometrical arrangement for a HATT’s blades.
Much of the technology behind the geometry of a HATT
comes from the wind turbine industry. However, when
attempting

to effectively capture the tide of a body of water,
elements such as the angle of a HATT’s blade must be
carefully examined to obtain efficient results.

Before examining test results, it is important to
understand how certain data points were achieved. I
n a test
site facility for tidal turbine analysis, there must be a water
flume present in order to artificially provide a steady current
of water. The results from tests done in the University of
Liverpool will be examined in this paper. It is said that
the
ideal tidal speed for a HATT is 2
-
3 m/s because higher
speeds ca
n lead to loading problems [4
]. However, for
testing purposes, a steady flow of 1 m/s is stable enough to
bring back steady test results.

Before experimentally testing
the results of the
ir physical arrangement, the team at the
University of Liverpool first attempted to find the optimal
blade angle using computational fluid dynamics (CFD). In
this experiment, the blade angle is defined as the angle
between the chord at the tip of the blad
e and the normal
vector to the rotational axis of the turbine hub assembly [4].
The CFD analysis for this power optimization uses the
Reynolds Stress Model, which computationally calculates
the Reynolds
-
Averaged Navier
-
Stokes (RANS) equations.
The RANS e
quations are time
-
averaged equations of motion
for fluid flow, and they are derived using a complicated
process called Reynolds decomposition. CFD programs take
care of these complicated calculations to simulate the flow
of water. In order to accurately
simulate the physical
experiment that would be run later, all the parameters were
set as if it were the physical experiment.
The flow of the
fluid was set to a constant 1 m/s, and the turbulence intensity
was set to 5%.
For the run, t
he blade pitch angl
e
was varied
between 0° and 12°.

The torque, and consequently the power
constants (C
p
)
were calc
ulated for the different blade angles.


C
p
= T
ω
/(0.5*
ρ
av
3
)




(1)

[4]


By acquiring corresponding values for the torques (T) of
each angle and vary
ing the angular momentum of the blades
(
ω
), (1) can be used to calculate the resultant power
coefficient.

Therefore, the power coefficient versus the blade
pitch angle can be plotted. The CFD trial shows the HATT
to be most efficient when the blade angle
is 6°.




FIGURE 1

CFD

P
REDICTED
O
PTIMAL
B
LADE
P
ITCH
A
NGLE
[3]


This result for the CFD trial urges the physical
experiment to keep the blade angle range close to 6° when
testing. Now, the physical
experiment can run with the same
parameters; however, it can now have within a shortened
range of 3° to 9°. After the data for power and angular
velocity is measured and plotted, a best
-
fit line shows the
general region for the results at each of the thre
e angles
observed. In this physical experiment, the optimal angle was
3 degrees. However, at the ideal angular velocity values, the
difference between the power at 3 degrees and at 6 degrees
is only a couple watts [4].




FIGURE

2

T
URBINE
P
OWER AT


,



,



B
LADE
A
NGLES
[4]


In conclusion, while there was some discrepancy
between the optimal blade angle values found using CFD
and the values found using the experimental data, the
differences between the power produced at 3° and 6° where
miniscule. The
refore, for efficient energy management, the
HATT should set their blade pitch angles in this sensible
range from three to six degrees.




Ryan Dolan



Daniel Kueffner

3

U
SING
A
DAPTIVE
B
LADES

Extending upon the analysis of the blade angles of a HATT,
there are so many other factors present

in underwater
systems as opposed to those existent in wind turbines that
the use of an adaptive and reactive system for HATTs could
significantly upgrade their efficiency. Due to differences in
fluid density, for instance, the thrust on a HATT is typical
ly
three times greater than that experienced by a horizontal axis
wind turbine, despite the tidal device having a significantly
smaller swept area. Other forces present on a HATT include
increased cyclic loads, cavitation, boundary layer
interference, wave

loading, parked extreme loads, and
operating fatigue loads. The variation in static pressure and
velocity across the vertical water column also imposes
interesting dynamic effects on the rotor blades; the tip of a
blade of a typical 15m diameter rotor wi
ll experience a 1.5
bar cyclic pressure variation as it moves from the top to the
bottom of its circular path, in addition to potentially large
velocity fluctuations [5].

One of the main concerns that could diminish the
energy production on the HATT is the

effect of cavitation on
the blades. Cavitation is the formation and immediate
implosion of cavities (bubbles) in a liquid, and it tends to
occur towards the ends of the blades on the face and near the
tip reducing the efficiency of the blades and thus th
e turbine
as a whole. Cavitation also brings forth the additional
problem of erosion on the blade material [5]. The cavitation
inception is the point at which the local negative pressure of
a section rises above the vapor pressure of the fluid. This
sec
tional volume of liquid will then rupture and form a
cavity. With this knowledge, the goal for a HATT would be
to have a blade with as even a pressure distribution as
possible.

In an experiment using a 2.5 m/s flow, the trailing edge
deflection of a HATT
blade is increased so the power
coefficient (C
p
) can be analyzed.


FIGURE 3

P
OWER
C
OEFFICIENT
M
EASURED AT
I
NCREASING
D
EFLECTION
[5]


It can be observed that the C
p

distribution on the upper

surface of the foil becomes increasingly less negative with
an

i
ncrease in trailing edge deflection, however that of the
lower

surface becomes increasingly more positive.
Cavitation is

most likely to occur
at the pressure peak,
where
the
pressure drop is greatest on the
foil
. This occurs

on the
lower

sur
face at an
angle of attack of 0
°
. Analyzing both the
upper

and

lower distributions in Figure 3
, it is apparent that
a section

exhibiting less twist in the latter portion is more
efficient at the

lower angle of attack of around zero to six
degrees [5].

Figure 4 shows
the pressure coefficient as a function of
the turbine radius for the different experimentations ran.
First, the data was collected from a turbine with a fixed
blade and then with a blade with a 3
°

pitch angle. The
subsequent trials where then performed u
sing adaptive
blades with a variable pitch distribution or a twisted
distribution. At a flow velocity of around 2 m/s, the
cavitation inception occurs at the areas of the blade where
the pressure coefficient is less than
-
2 [5].

Both of the fixed blades exhibit a maximum negative C
p

of less than
-
2. Therefore, these blades will cavitate at this
flow velocity of 2 m/s. Imposing a twist configuration on
the blade causes the C
p

over the outer two thirds of the blade
to decrease dras
tically [5].


FIGURE 4

P
RESSURE
D
ISTRIBUTION AS A
F
UNCTION OF
T
URBINE
R
ADIUS FOR THE
V
ARIOUS
T
WIST
D
ISTRIBUTIONS AND
C
ONFIGURATIONS
[5]


Clearly, the most successful configuration is that of the
variable pitch blade with the second pitch distribution
impo
sed on it. This particular configuration produces the
least negative value for its maximum C
p
, and it also
produces the most even pressure distribution. However, all
of the blades that have been altered from the base design
perform well in this experiment

and the likelihood of
cavitation occurring for the configurations with altered
blades has been significantly reduced [5].






Ryan Dolan



Daniel Kueffner

4

TABLE I

M
AXIMUM
N
EGATIVE
C
P

FOR THE
V
ARIOUS
B
LADE
T
WIST
C
ONFIGURATIONS
[5]

Blade Configuration

Maximum Negative C
p

Fixed Blade,
no pitch

Fixed Blade, 3° pitch

Variable Pitch Distribution 1

Variable Pitch Distribution 2

Twisted Distribution 1

Twisted Distribution 2

-
2.57

-
2.03

-
1.42

-
1.19

-
1.52

-
1.33


These experiments and their analysis have shown that
the combination of a fixed pitch and passively twisting blade
is likely to increase the profitability of a free stream tidal
turbine in comparison with a rigid fixed pitch or variable
pitch mechanism tur
bine. This reduction in cavitation
inception allowed for a 2.5% increase in energy efficiency.
Not to mention, there was also a 14.5% decrease for the
thrust coefficient necessary in comparison to the original
design [5]. Using CFD and experimental resu
lts, we found
that the concept of using an adaptive twisting blade truly
increases the efficiency on a horizontal axis tidal turbine.


O
PERATION AND
M
ANAGEMENT

New sources of energy and new sources of technology all
require much research on the operation
and science behind
the equipment. Operations

must be upheld to even the most
minuscule details in order for all tasks to run smoothly and
the procedure to be complete. The efficiency aspect of the
HATT operations needs to be top on the line with such
intr
icate science. Although the energy source is mostly
foreseeable, the operations regarding the HATT need to be
running
effectively

to achieve this for mentioned level of
energy
efficiency
. The major topics dealing with
management can fall underneath one of

three categories:
lifetimes of HATT, upkeep of tidal equipment, and routine
maintenance checks.


The lifetime

of the HATT is a major aspect of the
operation and management that goes into running a HATT
farm
. Due to the nature of the HATT and its recent

research,
lifetimes have yet to be determined. Studies in the United
Kingdom and Canada have estimated the lifespan for a
HATT farm to be anywhere from twenty to thirty years [
6
].
Tidal energy is an inchoate technology; therefore
,

it is
impossible to hav
e had any HATT running for twenty years
to prove the United Kingdom and Canada’s hypothesis true.
Such an emergent science needs to be studied further and
developed in a practical approach before assumptions based
on lifetime are recorded. The reason why
such speculations
have been made though is because of the offshore platforms.
Research has been done on offshore platforms that can be
recorded as twenty to thirty years but that data was not for a
HATT farm. A HATT farm platform may have a longer
lifespa
n or even a shorter one. The lifetime of a HATT is a
serious factor when dealing with cost effectiveness in
comparison with the energy o
utput; therefore investigations
need to be mandated to unlock new secrets of the HATT and
its energy production.

As stat
ed previously, the offshore platforms of the
HATT farm have been assumed to be the cause of the
lifetime. Upkeep of the offshore platforms can break the
limitations imposed on the entire HATT farm. The offshore
platforms are vital to operations and thus n
eed to be handled
accordingly. Routine maintenance needs to be done, which
is not as demanding as maintenance on the HATT itself, but
still important to smooth performances.

Going along with the lifespan of the HATT is
this
aforementioned

routine maintena
nce. One major reason why
the HATT seems so appealing to energy efficiency is that
recent studies have shown it has been producing energy
without failure or severe maintenance over a five
-
year term
[
6
]. A five
-
year term without a maintenance system in plac
e
poses as a great relief and shows how if the farm was
managed under some sort of maintenance process
,

the
lifetimes could shock researcher and even outshine other
alternative energy sources. Without breaking to
o

much into
the cost factor, hiring workers
to maintain the farms could be
very effective in elongating the lifespan of the HATT farms
and ultimately producing energy at a unimaginable rate to
prove how the HATT is a true source of alternate efficient
energy.

These three subgroups of operation are
in need of more
research as of now, but they are showing appealing results.
Cause for optimism is acceptable because of the promising
research performances that the HATT has demonstrated,
especially dealing with the five
-
year term without
maintenance. Mor
e time and money should be spent on
unlocking the mysteries of the HATT, but cost limitations
will be discussed in the next section.

C
OST

A main aspect that strictly determines efficiency of newly
found technology is the cost of operation and other
various
cost.


T
he cost of operation and other related maintenance
costs would be a diminutive obstacle when compared to the
energy production and efficiency. Cost can be summed up
by construction, running costs, and other factors affecting
the running co
sts.

Construction costs could be very pric
e
y although when
compared to other alternative energy construction costs such
as wind turbines or solar panels
,

the cost is extremely less.
This reduction in price has to deal with the energy it
produces and how i
t is
for the most part
c
onstant
. Studies
have shown that the price of manufacturing a HATT farm is
sixty percent of what the price of manufacturing for a solar
plant or wind turbine farm

would be

[
7
]. Construction costs
also bring up another major discuss
ion point of individual
HATT placement.

The main t
w
o options that poses quite a controversy in
individual HATT placement is whether or not to spread the
turbines out or keep them closer together. The major



Ryan Dolan



Daniel Kueffner

5

question deals with efficiency of how energy outp
ut can be
optimized along with minimizing the cost. The first idea of
placement is to have each individual HATT distant from the
next to maximize the current entering each one. Isolation of
each turbine allows it to work on its own and produce its
own cha
nnel and take on the current as a whole by itself to
produce the maximum amount of energy possible [
6
].
Naturally there as to be a flaw with this setup or else there
would be no second option of networking because this
format would result in the largest a
mount of energy
produced. The flaw with this is that the cabling would be the
most expensive because we would be running networks of
cables to various different locations that would increase cost.
The second placement technique is keeping a close network
of HATT
s

together in a downstream format. Although the
close network would take off a significant amount of current
passing through one HATT to the next it is extremely
profitable to keep them close. As discussed previously,
based on wake effect patterns
, we can

see how the flow is
interfere
from on
e

HATT to the next

if they are aligned in
tandem
.
However, if aligned side by side, the proximity of

each HATT in the farm keeps costs reasonable because the
cabling is significantly less complicated as well as being less
distant

for

wiring [
6
]. Both methods pose great opportuniti
es
to exceed energy output and manage costs. However, the
most efficient
pl
acement
for these HATTs would be side by
side in a reasonable proximity.

Running costs and maintenance costs are smaller topics
to deal with
,

but
they are
still important when factoring in
total energy output in comparison to total cost. Because
currents a
re very stable and tend not to fluctuate
all too
often, energy is usually being outputted at a constant flow
and therefore makes it easier to predicate how much energy
will be produced over some time interval. Maintenance costs
have been shown to follow th
e same type of pattern as that
of the construction cost. Due to its
rather
constant energy
output, the maintenance is usually regulated to be about
forty percent of that of solar plants [
7
]. These two specific
costs have implications to the total cost tha
t needs to be
evaluated with energy to decide if the HATT is
an

efficient
means of creating alternative energy.

The last aspect pertaining to cost is how to actually
compare it to energy output. This variable (O&M cost) is
defined by operation and mainten
ance cost and is found by


unit O&M cost =
Σ
omc
(i)

/

(
Energy)


(2) [
6
]


In (2), the
omc
(i)
variable refers to the value of
maintenance cost per year
i.
Divided by the energy output
that is given by



Energy = f
m
f
e

f
t
f
o
(L/2*
ρ*A*V^3)



(3)

[
6
]



In (3), the
Energy
is given by the preceding formula
where the
f

variables are fractional portions

lost due to
mechanical, electrical, tidal and

other reasons respectively.
L
is the predica
ted lifetime of the HATT. T
he density of

ocean
or river water

is defined as ρ, and

A and V are the area of
the turbine and the drift velocity of the designated current
[
6
]. Utilizing (2) and (3) will allow researchers to evaluate
the energy output and compare it directly to the previously
defin
ed O&M cost per HATT. Tracing back to the farm size
variable, the larger
,

more energy favorable farms will
produce more energy but the
omc
(i)
will be greatly raised as
well
.

This results

in a
n equivalent O&
M cost as a small farm
with low energy output and
a lower
omc
(i)
variable.

Through
all of this information dealing with cost and energy and
deciding how efficient this machine could be, speculations
have been made to find a middle ground of farm size to
produce enough energy to be effective but to minimiz
e the
cost.


E
NVIRONMENTAL
E
THICS



Plunging numerous amounts of such advanced and
experimental machinery will surely have an effect on the
ecosystem around each HATT and the environment as a
whole. Most criticisms of the HATT come from the false
speculation that it will disrupt the current patterns and
potentially be lethal to the ecosystems surrounding it.
Studies have been conducted against these assumptions and
have proven them wrong as well as showing clear reason to
why the HATT is, ethicall
y, a great source of untapped
energy that needs to be seriously looked into [
8
]. Effects of
the HATT on the environment can be broken down into
either one of two main categories: visual disruption or
ecosystem interference.

The visual disruption speculation is the less likely of the
two concerns, but still worthy of being discussed. These
HATT farms are in need of an offshore hub that will be
above water
and

will need to emit light. During the day, this
offshore hub, also kn
ow as a beacon, is said to be not
aesthetically appealing to the tourist industry and other
inhabitants of the shoreline. One can see where this
complaint is coming from even though the beacon is far
enough off shore that it is practically invisible. Dur
ing the
night, the complaints are being made that the beacon is
disrupting due to its light pollution. By law and safety
regulations
,

this light must be in place to alarm any offshore
boats traveling in the area, just as a lighthouse would.
Since

the HAT
T light beacon has a less powerful light and are
further off the shoreline from any lighthouse
,
complaint
s
have

not come up as often. The cure to both of these similar
criticisms is to place the HATT farms not only in current
favorable areas, but also in l
ess populated coastal regions
where the populace is less likely to notice or object to its
position.

The major of the two categories of grievances is the
effect on the ecosystem surrounding these HATT farms. The
major anxiety that have been proven untrue
is that the so
-
called ‘blade’ of the HATT could slice fish, marine



Ryan Dolan



Daniel Kueffner

6

mammals and even birds that dive underwater. First to
correct a common misconception with the HATT, the
‘blade’ that is being referred to is not something sharp or
extreme lethal that sh
ould be of concern. The ‘blade’ is
merely a smooth, plastic edge that will have dull sides to it
unable of doing severe damage to substances traveling
through it. A hierarchy of
conditional statements describes

how the HATT is not harmful to animals. HA
TT farms are
only placed in high current flow areas, so most of the
animals in this ecosystem are well adapted to
high
-
speed

water and thus are predicted to be able to avoid the HATT
blades due to
their

agility in high flow water. If they are
unable to av
oid the blades the odds that they actually hit a
blade on their passing through the turbine is aro
und a six
percent chance [
8
]. Lastly, the worst
-
case scenario is that
the animal would hit the blade and even in this case it would
not be lethal. Water hit
s the HATT blades at an angle that is
less than ten degrees, and if an animal were to hit the blade a
slight graze or a bump would occur and it may or may not
disrupt the HATT motion for a moment. Studies have
shown that there would be no severe or lethal

damage done
to the animal and therefore we can conclude that this
category of concern is also based on false speculations.

Comparisons of the HATT have been made to boat
rotors or propellers. Propellers have a greater angle than that
of any HATT and ther
efore can attract substances towards it,
which the HATT does not due to its smaller blade angle.
The blades on a boat

s propeller are also sharp and capable
of lethal damage to animals, which the HATT is not due to
its blunt edges [
8
]. Although boat prop
ellers are on the
surface of the water and also move throughout the water and
are not stationary they still pose a greater threat to animals
than that of the HATT.

Ethical assumptions about the HATT have been made
but ultimately have been deemed false due
to experiments on
their specific concerns. Placement of the HATT will has
proven to not have any severe effects on the environmental,
so the HATT should be placed in the most suitable
conditions to optimize energy. In other words, locate the
HATT in the mo
st appropriate locations to maximize the
efficiency of this new energy source. Although most of the
major criticisms have been proven false, other worries may
arise that could be considered dangerous and proven risky to
those ecosystem and environment ar
ound it. Now knowing
most of the HATT experimental results, one can see how it
is ethically stable and should be given more seriousness in
terms of alternative energy.


C
ONCLUSION

The ocean is a key resource to our everyday lives, and with
the HATT, the oc
ean’s power can be untapped even further
to expand our technology and science. Although various
other forms of alternative energy have had more in
-
depth
research and have been studied longer, the HATT’s research
is showing a lot of promise. Studies have c
onfirmed that the
HATT will produce sufficient energy, but the major
argument is over the rate at which it can be efficient.
Numerous experiments have been done to figure out the
optimal blade geometry to maximize its efficiency. Other
adaptive blades have

also been altered with CFD technology
to further improve the HATT.

The other side to the HATT controversy is the ethical and
monetary portion of its research. The operation and
management effects were important parts in evaluating the
efficiency of the HA
TT farms. Going along with the HATT
farms is the argument of placement of individual HATTs to
optimize energy or to minimize cost. Moving onto another
debate dealing with the HATT studies is the effect on the
environment. Arguments supporting that the HAT
Ts would
disrupt the ecosystems around them were proven false.
From an ethical standpoint, the HATT is seen as a more
affordable source of energy that will cause little to no
damage on the environment. The HATT poses a new source
of energy to science that

will established an example of how
society can utilize the world around us for our own benefit
and for the world’s safety
.

R
EFERENCES

[1]
A. Macleod, S. Barnes, K. Rados, I. Bryden. “Wake effects in tidal
current turbine farms.”
The Robert Gordon Universi
ty
. Available:

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919X.2006.00518.x/full#ss8






Ryan Dolan



Daniel Kueffner

7

A
DDITIONAL
R
ESOURCES
S
ECTION


S. Mollman. (2003, May). “Tapping the Tides.”
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[Online]. Available:
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A
CKNOWLEDGMENTS
S
ECTION

We would like to thank all of our engineering professors and
teachers in high schoo
l for inspiring in the engineering field.
Special thanks goes out to our engineering conference co
-
chair, Ryan Soncini

for helping us with our topic, as well as
both our conference chairs who have taken time out of their
own busy schedule to help us.
Also,

we would like to say
thanks to our writing instructor for advising our paper along
the way as well as giving us constructive criticism. Lastly,
we would like to show our appreciation to our friends and
family for their support.