a ddaskalakis aquaculture-engineeringtechnology-oct 19-17+10-p-pdf

AQUACULTURE EUROPE 2011

OPEN SEA FISH FARMS BASED ON INTEGRATED

INTENSE FLOATATION AND WAVE ABSORBING

TECHNOLOGIES

OFFSHORE ENERGY SYSTEMS SA

Address: 48 Karaoli & Dimitriou str., GR-152 32 Halandri, Greece

Tel. +30 210 6775 003, Fax +30 210 6812 770, www.martech.gr, email: tech

Presented by : Dr Antonis DaskalakisOffshore Energy Systems SA

OPEN SEA FISH FARMS BASED ON INTEGRATED

INTENSE FLOATATION AND WAVE ABSORBING

TECHNOLOGIES

[email protected]

Presented by : Dr Antonis DaskalakisOffshore Energy Systems SA


WHY DEEP WATERS

Moving to deep waters and far from the coasts is inevitable due

�Increased pressures from local communities�Contradiction with other social and economical activities�Increased concerns on health and environmental issues

However it is for the benefits of the industry itself to seek ways of doing so.




�The limited space for development, leading to small size units and a disperse activity.�The confined self cleaning capability of protected waters.�Fish health problems and decease spreading, affect productivity and quality.�Fish growing speed and fish taste which improve considerably in deep waters

WHY DEEP WATERS

Moving to deep waters and far from the coasts is inevitable due to:

Increased pressures from local communitiesContradiction with other social and economical activitiesIncreased concerns on health and environmental issues

However it is for the benefits of the industry itself to seek ways of doing so.

[email protected] Presented by : Dr Antonis Daskalakis

The limited space for development, leading to small size units and a disperse

The confined self cleaning capability of protected waters.Fish health problems and decease spreading, affect productivity and product

Fish growing speed and fish taste which improve considerably in deep waters


WHY DEEP WATERS

Costs involved in going into deep waters will be compensated by:

�Concentrating production into a small but of considerable size units increasing capacity, reducing production and logistic costs.

�Improving the quality of the product and widening the market horizons.




�Cultivating new fish species, increasing product variability and market penetration.

INTEGRATED TECHNOLOGIES HAVE TO BE DEVELOPED

WHY DEEP WATERS

Costs involved in going into deep waters will be compensated by:

Concentrating production into a small but of considerable size units increasing capacity, reducing production and logistic costs.

Improving the quality of the product and widening the market horizons.

[email protected]

Cultivating new fish species, increasing product variability and market

INTEGRATED TECHNOLOGIES HAVE TO BE DEVELOPED

Presented by : Dr Antonis Daskalakis


THE MOVE TO DEEP WATERS IS ALREADY A REALITY

�Extensive research and investment efforts are undertaken worldwide. More than $100 million have been spent in USA over a decade.

�USA, China, Chile, Israel are reported to lead the efforts.

�Main focus is put on sank cages in order to avoid the effects of the sea waves.

�The blue revolution in Hawaii, the subflex in Israel, the “ i




�The blue revolution in Hawaii, the subflex in Israel, the “ i installations.

However ,

�A new production process is necessary and special skills have to be developed in order to realize this type of production.

We believe that staying at surface presents a challenge which has to be answered, for many reasons.

THE MOVE TO DEEP WATERS IS ALREADY A REALITY

Extensive research and investment efforts are undertaken worldwide. More than $100 million have been spent in USA over a decade.

USA, China, Chile, Israel are reported to lead the efforts.

Main focus is put on sank cages in order to avoid the effects of the sea waves.

The blue revolution in Hawaii, the subflex in Israel, the “ i 0cagesi+ ” , are such


The blue revolution in Hawaii, the subflex in Israel, the “ i cagesi+ ” , are such

A new production process is necessary and special skills have to be developed in order to realize this type of production.

We believe that staying at surface presents a challenge which has to


WHAT IS INTENSE FLOATATION TECHNOLOGY

BODY UNDER INTENSE FLOATATION: BASIC MORPHOLOGY

• The main buoyant unit (MBU) that produces buoyancy in excess of the body total weight.

• The columns that support and connect the deck with the MBU providing variable buoyancy.




with the MBU providing variable buoyancy.• The deck structure that provides space and

undertakes the live loads.• The anchor lines that connect the body with the

sea bed being always under tension.• The anchor blocks which can undertake the

tension from the lines and providing horizontal holding power.


BODY UNDER INTENSE FLOATATION: BASIC

(MBU) that produces buoyancy in excess of the body total weight.

that support and connect the deck with the MBU providing variable buoyancy.

[email protected]

with the MBU providing variable buoyancy.structure that provides space and

that connect the body with the

which can undertake the tension from the lines and providing horizontal




A BODY UNDER IF IS SUBJECTED TO WEATHER FORCES ,LIKE ANY OTHER BODY AT SEA

However the following make it to present a peculiar behavior:

1. The MBU is below the water to reduce wave forces and for a safe operation.




and for a safe operation.2. The body presents a small water plane area reducing

wave forces.3. The fairleads are forced to move on circular

trajectories. 4. Only planar motions are present with only a small

heave movement. In fact the body moves on the plane parallel to itself with its deck always horizontal

5. The line lengths are kept short compared to mooring lines.


A BODY UNDER IF IS SUBJECTED TO WEATHER FORCES

However the following make it to present a peculiar

The MBU is below the water to reduce wave forces

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The body presents a small water plane area reducing

The fairleads are forced to move on circular

Only planar motions are present with only a small heave movement. In fact the body moves on the

deck always horizontal.The line lengths are kept short compared to catenary



MATHEMATICAL MODELLING OF AN INTENSE FLOATATION BODY

The mathematical formulation follows the same lines as for a free floating body based on Newton’s second law:

(M + A11)(u '− rv ')+ B11u = Fx∑(M + A

22)(v '+ ru)+ B

22u = Fy∑

(I + A )r '+ B r = FM∑

surge

sway

yaw

THE PECULIARITIES OF AN IFB PROVIDE USEFUL CHARACTERISTICS. HOWEVER INTENSE STUDY BEFORE BUILDING AN INTENSE FLOATATION TECHNOLOGY




The total forces exerted on the body (in the three directions) are:

Fm : Forces from the mooring linesFw : Weather forces (wind, waves, currents) and FFl (high and low frequency excitations)Fo : Live or operational forces (loads)

(I66

+ A66

)r '+ B66

r = FM∑ yaw

ioiwimiFFFF ++=


The mathematical formulation follows the same lines as for s second law:

THE PECULIARITIES OF AN IFB PROVIDE USEFUL CHARACTERISTICS. HOWEVER INTENSE FLOATATION TECHNOLOGY.

[email protected]

The total forces exerted on the body (in the three

: Weather forces (wind, waves, currents) and Fw = Fh +




IMPORTANT NOTES

• The importance of separating the mathematical model into low and high frequency.This is because natural frequencies of an IFB can be within the band of low frequency excitations like swells.

• The body as it is described here operates like an




• The body as it is described here operates like an inverted pendulum and its natural frequency is given by:

Under certain circumstances it is possible natural frequency to avoid excitations. This can be done during design but also during operation.

ωn =Pa

MaL

Pa : excess buoyancyMa: body mass + added massL : line length


The importance of separating the mathematical model

This is because natural frequencies of an IFB can be within the band of low frequency excitations like swells.

The body as it is described here operates like an

[email protected]

The body as it is described here operates like an inverted pendulum and its natural frequency is given

Under certain circumstances it is possible to tune the This can be done

: excess buoyancy: body mass + added mass

L : line length




RESULTS FROM THE SIMULATION PROGRAM IN HARMONIC WAVES OF AN INTENSE FLOTATION WIND MEASUREMENT PLATFORM

Total wave force in KNInput Values




Total wave force in KN

The variation of line tension and total Excess buoyancy

Input Values

Wave Height (m) 8

Wave Period (sec) 6

Mean wind speed (m/sec) 36

Current speed (Knots) 1.5


Total wave force in KN Excursions of the platform (m)

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Total wave force in KN Excursions of the platform (m)

The variation of line tension and total Excess

An IF Wind Measurement Platform



CALCULATING PROCEDURES OF AN INTENSE FLOATATION BODY

BASED ON THE GENERAL MATHEMATICAL MODELING EACH COMPONENT NEEDS AN INDIVIDUAL STUDY ACCORDING TO ITS ROLE.

The body itself: Two main areas of interest: � The body motions, � Its strength for the design loads (environmental and operating).Extreme conditions and special low frequency phenomena




Extreme conditions and special low frequency phenomena can be studied. Wave forces are calculated based on Morison's equation.For the strength calculations a finite element model developed in SAP-2000. is developed.Mooring lines: Tensions under all circumstances are calculated from time domain simulation.Anchors: Calculated minimum weight (for gravity anchors) and required holding capacity.

CALCULATING PROCEDURES OF AN INTENSE FLOATATION BODY

BASED ON THE GENERAL MATHEMATICAL MODELING EACH COMPONENT NEEDS AN INDIVIDUAL STUDY ACCORDING TO ITS ROLE.

Two main areas of interest:

Its strength for the design loads (environmental and

Extreme conditions and special low frequency phenomena

[email protected]

Extreme conditions and special low frequency phenomena

Wave forces are calculated based on Morison's equation.For the strength calculations a finite element model

Tensions under all circumstances are

minimum weight (for gravity



TECHNOLOGIES TO EXPLOIT INTENSE FLOATATION BODIES

BODY DESIGN AND REALISATION

• Simple structures are developed for minimum forces, easy installation and minimum maintenance.

• To lower costs and increase flexibility, the main buoyancy module is split into two major parts :1. Permanent buoyant volume 2. Water tanks for ballasting and de-ballasting




• Modular structures are developed which can be connected together to form the required area and capacity.

• Vertical floaters can be either the strength members of the body or just buoyant units.

• Special connectors are developed (screw, wedge type connectors, elasto-dynamic bearing type connector


Simple structures are developed for minimum forces, easy installation and minimum maintenance.

To lower costs and increase flexibility, the main buoyancy module is split into two major parts :

ballasting

[email protected]

are developed which can be connected together to form the required area and capacity.

Vertical floaters can be either the strength members of the

are developed (screw, wedge type dynamic bearing type connector




MOORING LINE DESIGN AND REALISATION

• The mooring lines can be of wire rope (or even synthetic rope of high strength).

• Each line is composed by a number of individual lines (block of lines) so that :�the required loads can be undertaken, under all conditions,




conditions,�redundancy can be provided, �while a line can be replaced in situ.

• Special universal connectors are developed that provide :� Movements in all directions� Easy fitting of a number of individual lines to form

a complete block of an anchor line.� Easy handling and securing


MOORING LINE DESIGN AND REALISATION

The mooring lines can be of wire rope (or even synthetic

Each line is composed by a number of individual lines

the required loads can be undertaken, under all

[email protected]

Special universal connectors are developed that

Easy fitting of a number of individual lines to form a complete block of an anchor line.




ANCHORS DESIGN AND REALISATION

• The anchors are a major component of the system. Undertake the excess buoyancy and provide holding capacity.

We introduce here the concept of the split anchor

• Knowledge comes the oil industry in designing and constructing effective anchors.




We introduce here the concept of the split anchor � The first part, a block is preinstalled at the sea bottom . � The body itself carries the second part, anchors which during transportation and installation function as ballast weights.� During installation the anchors are lowered to specially designed sockets on the preinstalled block. � The preinstalled block provides precision and ease of installation.


The anchors are a major component of the system. Undertake the excess buoyancy and provide holding capacity.

split anchor .

Knowledge comes the oil industry in designing and

[email protected]

split anchor .The first part, a block is preinstalled at the sea bottom . The body itself carries the second part, anchors which

during transportation and installation function as ballast

During installation the anchors are lowered to specially designed sockets on the preinstalled block.

The preinstalled block provides precision and ease of



APPLICATIONS OF THE IN INTENSE FLOATATION TECHNOLOGIES

FISHING CAGES

Fishing cages for deep and very deep waters are designed as intense floatation bodies.:In several shapes and sizes depending on the requirements.In heights according to prevailing wave climate.With deck height depending on the platform envisaged use.It can be workable at any conditions or it can be allowed to be washable above certain conditions.




washable above certain conditions.

Net design is of particular importance. Instead of the freely moving net following the current forces we propose the double net arrangement.� The first is external and more or less permanently attached to

the mooring lines or to additional auxiliary vertical lines. It is open at the top and at the bottom as well extends as deeply as it is required.

� The second is the fish net, which is kept inside the external net. It can be a normal or a sinkable one.


Fishing cages for deep and very deep waters are designed as

In several shapes and sizes depending on the requirements.In heights according to prevailing wave climate.With deck height depending on the platform envisaged use.It can be workable at any conditions or it can be allowed to be

[email protected]

Instead of the freely moving net following the current forces we

The first is external and more or less permanently attached to the mooring lines or to additional auxiliary vertical lines. It is open at the top and at the bottom as well extends as deeply

The second is the fish net, which is kept inside the theexternal net. It can be a normal or a sinkable one.




FISHING CAGES

• Fishing cages are of modular structure and they can be connected with several ways to form a complete unit:

• The hexagon shape provided here is only one of the possible formulations>

• The cages can be organized in subunits according to the production needs.




production needs.• Supporting structures, like working platforms, can also be

arranged accordingly.


Fishing cages are of modular structure and they can be connected with several ways to form a complete unit:The hexagon shape provided here is only one of the possible

The cages can be organized in subunits according to the

[email protected]

Supporting structures, like working platforms, can also be




WORKING PLATFORMS

• Working platforms can be designed and constructed as IFB to serve all the needs of a complete installation.

• Working platforms are of modular construction and they can be connected together to form the shape, the required load area, the necessary payload.

Working platforms can carry :�Silos and feeding apparatus




�Silos and feeding apparatus�Offices and working spaces�Warehouses and machinery spaces�Accommodation facilities�Crew recreational installations

A two storey accommodation facility


Working platforms can be designed and constructed as to serve all the needs of a complete installation.

Working platforms are of modular construction and they can be connected together to form the shape, the required


A two storey accommodation facility An open door personnel recreational platform



LIGHTING AND SURVEILANCE TOWERS • Lighting towers are IFB designed to carry a lattice

type tower of adequate height.• Photovoltaic panels can gather enough energy to

feed the lights installed at the top of the tower, while a battery set can store energy for the night hours .

• A small generator which automatically turns on when the battery charge goes down can secure complete




the battery charge goes down can secure complete energy autonomy.

• A small enclosed area can be provided for a night guard with substantial facilities.

• Wireless Cameras (also thermal) can provide an all day and night surveillance.

• A megaphone system can be used for direct communication of the office with the plant.

• The tower can be installed from 30 m and up to deep and very deep waters.


Lighting towers are IFB designed to carry a lattice

Photovoltaic panels can gather enough energy to feed the lights installed at the top of the tower, while a battery set can store energy for the night hours .A small generator which automatically turns on when the battery charge goes down can secure complete

[email protected]

the battery charge goes down can secure complete

A small enclosed area can be provided for a night

Wireless Cameras (also thermal) can provide an all

A megaphone system can be used for direct communication of the office with the plant.The tower can be installed from 30 m and up to deep



WAVE ABSORBING TECHNOLOGIES

� The idea comes from the fact that wave energyis concentrated at and near the sea surface.

� In contrast gravity structures are build on a reverse order of mass distribution.

� We need something to interact with waves in the actual area of energy concentration.

WHY WAVE ABSORBERS

� The first idea leads to floating structures. But free floating




� The first idea leads to floating structures. But free floating structures move with the waves and produce waves.Existing breakwaters have a limited capacity up to 3sec of wave periods.

� We replace the free floating body with an IFB. Howver,� Wave breakers act as an obstacle to the waves, creating

huge forces.

� Instead of a perpendicular wall to waves we fill the empty space with wave absorbing cells.


The idea comes from the fact that wave energyis concentrated at and near the sea surface.In contrast gravity structures are build on a reverse order

We need something to interact with waves in the actual

Κατανοµή ενέργειας κύµατος

0

25

50

75

100

0 10 20 30 40 50 60 70 80 90 100

Απόσταση από την επιφάνεια ως ποσοστό (%) του βάθους

Κατανοµή

(%

) ενέργειας κύµατος

Τ = 2 sec

Τ = 5 sec

The first idea leads to floating structures. But free floating

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The first idea leads to floating structures. But free floating structures move with the waves and produce waves.Existing breakwaters have a limited capacity up to 3-3.5

We replace the free floating body with an IFB. Howver,Wave breakers act as an obstacle to the waves, creating

Instead of a perpendicular wall to waves we fill the wave absorbing cells.




There are several proposals for absorbing apparatus like the perforated plates. With the aim:

� To increase absorbing capacity, to minimize forces, to design something that can be produced under factory conditions,

WAVE ABSORBING CELLS

We have developed the cell type wave absorbers shown here

• The cells are of variable inclination in order to break the wave field into a number of counteracting wave fields.




wave field into a number of counteracting wave fields. • The cells are standardized in sizes and they can be installed

to fill the complete space between floaters and deck.

�Wave absorbers can be used to create ports, to protect coasts from erosion, to protect open water installations like aquaculture.

� The IFB, carrying the absorbing cells, consists a absorber module.

� Modules are connected together to form the complete wave absorber.


There are several proposals for absorbing apparatus like the

To increase absorbing capacity, to minimize forces, to design something that can be produced under factory conditions,

wave absorbers shown here

The cells are of variable inclination in order to break the wave field into a number of counteracting wave fields.

[email protected]

wave field into a number of counteracting wave fields. The cells are standardized in sizes and they can be installed to fill the complete space between floaters and deck.

Wave absorbers can be used to create ports, to protect coasts from erosion, to protect open water installations like

The IFB, carrying the absorbing cells, consists a wave

Modules are connected together to form the complete wave




The wave field of an incoming wave can be expressed as follows:

In the absorbing cells the field is “broken” to a number of fields Φi , and diffracted waves Φd.

THEORETICAL ASPECTS OF WAVE ABSORBING CELLS

d

dztx

gtzx

I κ

κωκι

ωι

cosh

)](cosh[)]([),,(

+−−=Φ

∑∑ Φ+Φ=Φ




The outgoing wave field ΦD with less energy content.The forces exerted on the cell surface are of reduced order.

Field tests of wave absorbers, and of a WAVE ENERGY EXPLOITATION (WECO) apparatus have been contacted in the area of Laurion.The results have led to a complete range of products.A first application is already working in the port of Laurion.

∑∑ Φ+Φ=ΦdD ι


The wave field of an incoming wave can be expressed as

to a number of

THEORETICAL ASPECTS OF WAVE ABSORBING CELLS

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D with less energy content.The forces exerted on the cell surface are of reduced order.

Field tests of wave absorbers, and of a WAVE ENERGY EXPLOITATION (WECO) apparatus have been contacted in the

The results have led to a complete range of products.A first application is already working in the port of Laurion.




�Floating wave absorbers of intense floatation for deep and very deep waters

� Bottom supported wave absorbers of a piled structure for shallow waters

PRODUCT RANGE

A complete range of wave absorbing products has been developed including:




structure for shallow waters

�Absorbing docks for internal port dock constructions


Floating wave absorbers of intense floatation

Bottom supported wave absorbers of a piled

A complete range of wave absorbing products has

[email protected]

Absorbing docks for internal port dock



OUR VISION FOR THE NEW ERA IN AQUACULTURE




OUR VISION FOR THE NEW ERA IN AQUACULTURE


a ddaskalakis aquaculture-engineeringtechnology-oct 19-17+10-p-pdf

Engineering