me165-1_week-7. energy from the ocean_1342170
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ME165-1
ALTERNATIVE ENERGY TECHNOLOGIES
Engr. EWeek-7 Energy from the Oceans2015-16 / 3T
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OCEAN ENERGY
• Ocean energy or ocean power (also sometimes referred to a
energy or marine power) refers to the energy carried by ocea
tides, salinity, and ocean temperature differences.
• The movement of water in the world’s oceans creates a vast
kinetic energy, or energy in motion.
• This energy can be harnessed to generate electricity to powe
transport and industries.
• The term ocean energy encompasses both wave power — po
surface waves, and tidal power — obtained from the kinetic
large bodies of moving water.
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OCEAN ENERGY
• Offshore wind power is not a form of marine energy
power is derived from the wind, even if the wind tu
placed over water.
• The oceans have a tremendous amount of energy a
close to many if not most concentrated populations• Ocean energy has the potential of providing a subst
amount of new renewable energy around the world
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OCEAN ENERGY
• Forms of Ocean Energy
IV. Wave Power
• The power from surface waves.
V. Ocean Thermal Energy• The power from temperature differences at varying depths.
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I. MARINE CURRENT POWER
• Marine current power is a form of marine energy obtained froharnessing of the kinetic energy of marine currents, such as th
stream.
• Marine current power has an important potential for future e
generation. Marine currents are more predictable than wind a
power.• A 2006 report from United States Department of the Interior
that capturing just 1/1,000th of the available energy from the
Stream, which has 21,000 times more energy than Niagara Fa
of water that is 50 times the total flow of all the world’s fresh
would supply Florida with 35% of its electrical needs.
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I. MARINE CURRENT POWER
•
Marine currents are caused mainly by the rise and fall of the tresulting from the gravitational interactions between earth, m
sun, causing the whole sea to flow.
• Other effects such as regional differences in temperature and
the Coriolis effect due to the rotation of the earth are also ma
influences.• The kinetic energy of marine currents can be converted in mu
way that a wind turbine extracts energy from the wind, using
types of open-flow rotors.
• The potential of electric power generation from marine tidal c
enormous.
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I. MARINE CURRENT POWER
• There are several factors that make electricity generation from
currents very appealing when compared to other renewables
• The high load factors resulting from the fluid properties.
• The predictability of the resource, so that, unlike most of othe
renewables, the future availability of energy can be known an
for.
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I. MARINE CURRENT POWER
•The potentially large resource that can beexploited with little environmental impact,
thereby offering one of the least damaging
methods for large-scale electricity
generation.
•The feasibility of marine-current power
installations to provide also base grid power,
especially if two or more separate arrays
with offset peak-flow periods are
interconnected.
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I. MARINE CURRENT POWER
• Early Experiences• The possible use of marine currents as an energy resource
draw attention in the mid-1970s after the first oil crisis.
• In 1974 several conceptual designs were presented at the
Workshop on Energy.
• In 1976 the British General Electric Co. undertook a partiagovernment-founded study which concluded that Marine
Power deserved more detailed research.
• Soon after, the ITD-Group in UK implemented a research
involving a year performance testing of a 3-m hydroDarrie
deployed at Juba on the Nile.
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I. MARINE CURRENT POWER
• Early Experiences (cont’d.)
• The 1980s saw a number of small research projects to eva
Marine Current Power systems. The main countries wher
were carried out were the UK, Canada, and Japan.
•
In 1992 –1993 the Tidal Stream Energy Review identified sin UK waters with suitable current speed to generate up t
TWh/year. It confirmed a total Marine Current Power reso
capable theoretically of meeting some 19% of the UK elec
demand.
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I. MARINE CURRENT POWER
• Early Experiences (cont’d.)• In 1994 –1995 the EU-JOULE CENEX project involved a res
assessment compilation of a database of European locatio
which over 100 sites ranging from 2 to 200 km2 of sea-bed
identified, many with power densities above 10 MW/km2
• Both the UK Government and the EU have committed theinternationally negotiated agreements designed to comba
warming.
• In order to comply with such agreements, an increase in l
electricity generation from renewable resources will be re
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I. MARINE CURRENT POWER
• Early Experiences (cont’d.)
• Marine currents have the potential to supply a substantia
future EU electricity needs.
• The study of 106 possible sites for tidal turbines in the EU
total potential for power generation of about 50 TWh/yea
• If this resource is to be successfully utilized, the technolog
could form the basis of a major new industry to produce
for the 21st century.
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I. MARINE CURRENT POWER
• Available technologies in marine-current-power applications• There are several types of open-flow devices that can be
marine-current-power applications; many of them are mo
descendants of the old concept of the waterwheel or sim
• However, the more technically sophisticated designs, der
wind-power rotors, are the most likely to achieve enough
effectiveness and reliability to be practical in a massive m
current-power future scenario.
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I. MARINE CURRENT POWER
• Available technologies in marine-current-power (cont’d.)
• Even though there is no generally accepted term for thes
hydro-turbines, some sources refer to them as water-cur
turbines.
• There are two main types of Water Current-Turbines thatconsidered: axial- flow horizontal -axis propellers (with bot
pitch or fixed-pitch), and cross- flow vertical -axis Darrieus
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I. MARINE CURRENT POWER
• Available technologies in marine-current-power (cont’d.)
• Both rotor types may be combined with any of the three
methods for supporting Water-Current Turbines: floating
systems, sea-bed mounted systems, and intermediate syst
•Sea-bed-mounted monopile structures constitute the firsMarine Current Power systems. They have the advantage
existing (and reliable) engineering know-how, but they ar
relatively shallow waters (about 20 to 40 m deep).
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I. MARINE CURRENT POWER
SEAGEN in Northern
Ireland’s Strangford
Lough.
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Osmotic power or salinity gradient power is the energy avail
the difference in the salt concentration between seawater a
water.
• Two practical methods for this are reverse electrodialysis (RE
pressure-retarded osmosis (PRO).• Both processes rely on osmosis with ion specific membranes.
• The key waste product is brackish water.• This byproduct is the result of natural forces that are being harness
fresh water into seas that are made up of salt water.
• The technologies have been confirmed in laboratory conditio
being developed into commercial use in the Netherlands (RE
Norway (PRO).
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• The cost of the membrane has been an obstacle. A new, che
membrane, based on an electrically modified polyethylene p
made it fit for potential commercial use.
• Other methods have been proposed and are currently under
development. Among them, a method based on electric doucapacitor technology and a method based on vapor pressure
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• The world's first osmotic power plant with capacity of 4 kW wby Statkraft on 24 November 2009 in Tofte, Norway.
• This plant uses polyimide as a membrane, and is able to p
1W/m² of membrane. This amount of power is obtained a
water flowing through the membrane per sec, and at a pr
10 bar. Both the increasing of the pressure as well as the
the water would make it possible to increase the power o
Hypothetically, the output of the SGP-plant could easily b
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Basics of salinity gradient power• Salinity gradient power is a specific renewable energy alte
that creates renewable and sustainable power by using n
occurring processes.
• This practice does not contaminate or release carbon diox
emissions (vapor pressure methods will release dissolvedcontaining CO2 at low pressures—these non-condensable
be re-dissolved of course, but with an energy penalty).
• Salinity gradient energy is based on using the resources o
pressure difference between fresh water and sea water.”
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Basics of salinity gradient power (cont’d.)
• All energy that is proposed to use salinity gradient techn
on the evaporation to separate water from salt.
• Osmotic pressure is the "chemical potential of concentra
dilute solutions of salt".When looking at relations betwee
osmotic pressure and low, solutions with higher concent
salt have higher pressure.
• Salinity gradient energy is based on using the resources o
pressure difference between fresh water and sea water.”
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Basics of salinity gradient power (cont’d.)
• All energy that is proposed to use salinity gradient techno
on the evaporation to separate water from salt.
• Osmotic pressure is the "chemical potential of concentrat
dilute solutions of salt".When looking at relations betwee
osmotic pressure and low, solutions with higher concentr
salt have higher pressure.
• Differing salinity gradient power generations exist but one
most commonly discussed is pressure-retarded osmosis (
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
Statkraft Osmotic Power
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
•
"Statkraft says osmotic power would be especially suitedgenerating electricity for large cities, situated where larg
into the sea and therefore not needing new transmission
• A commercial 25 megawatt plant would be the size of a
field.
• An osmotic plant could, however, have the same environimpact as a hydropower facility, so the right site is crucia
• "The new technology is based on the principle of osmos
diffusion of water through a semi-permeable membrane
how plants draw water from the soil.
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Fresh water and salt water is guided into separate chamb
divided by an artificial membrane.
• When the fresh and seawater meet on either side of the
membrane, the fresh water is drawn towards the seawat
• The flow puts pressure on the seawater side, and that pr
be used to drive a turbine, producing electricity."
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Basics of salinity gradient power (cont’d.)
• This method of generating power was invented by Prof. Sin 1973 at the Ben-Gurion University of the Negev, Beersh
• Within PRO, seawater is pumped into a pressure cham
the pressure is lower than the difference between fres
water pressure.
• Fresh water moves in a semipermeable membrane anits volume in the chamber.
• As the pressure in the chamber is compensated a turb
generate electricity.
II OSMOTIC POWER (SALINITY GRADIENT POWER)
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
• Basics of salinity gradient power (cont’d.)
• In Braun's article he states that this process is easy to u
a more broken down manner.•
Two solutions, A being salt water and B being fresh water area membrane.
• He states "only water molecules can pass the semipermeable
As a result of the osmotic pressure difference between both
water from solution B thus will diffuse through the membran
dilute the solution".
• The pressure drives the turbines and power the generator ththe electrical energy.
• Osmosis might be used directly to "pump" fresh water o
Netherlands into the sea. This is currently done using el
pumps.
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
Electricity By Osmosis
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II. OSMOTIC POWER (SALINITY GRADIENT POWER)
Electricity By Osmosis
III TIDAL POWER
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III. TIDAL POWER
• Tidal Power
• The energy from moving masses of water — a popular form of
hydroelectric power generation.
• Tidal Power Generating Methods
•TIDAL STREAM GENERATOR
• TIDAL BARRAGE
• DYNAMIC TIDAL POWER
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III. TIDAL POWER
• TIDAL STREAM GENERATOR
• Tidal stream generators (or TSGs) make use of the kinet
moving water to power turbines, in a similar way to win
that use wind to power turbines.
• Some tidal generators can be built into the structures of
bridges, involving virtually no aesthetic problems.
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III. TIDAL POWER
• TIDAL STREAM GENERATOR (CONT’D.)
• Tidal Stream is the name given to the horizontal flow of w
through the oceans caused by the continuous ebb and fl
tide, which as we know is the vertical up-down moveme
oceans water.
• Unlike water currents which are a continuous, unidirectioform a steady horizontal movement of water flowing dow
stream etc, a tidal stream or tidal current, changes its sp
direction and horizontal movement regularly according t
of the tide controlling it.
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III. TIDAL POWER
• TIDAL STREAM GENERATOR (CONT’D.)
• Tidal stream generation is a non-barrage tidal schem
extracts the kinetic energy (energy in motion) from m
water generated by the tides without altering the en
thereby making it a Hydrokinetic Energy system.
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III. TIDAL POWER
• TIDAL STREAM GENERATOR
The world's first commercial-scale and grid-connected tidal stream generator
– SeaGen – in Strangford Lough, Northern Ireland. The strong wake shows the
power in the tidal current.
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III. TIDAL POWER
• TIDAL STREAM GENERATOR
TidalStream Deep Sea Generators
Pentland Firth, Scotland, UK
http://www.youtube.com/watch?v=8-sFLGMSMac
http://www.youtube.com/watch?v=8-sFLGMSMachttp://www.youtube.com/watch?v=8-sFLGMSMac
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III. TIDAL POWER
• TIDAL BARRAGE
•
Tidal barrages make use of the potential energy in the dheight (or head) between high and low tides. When usin
barrages to generate power, the potential energy from a
seized through strategic placement of specialized dams.
• When the sea level rises and the tide begins to come in,
temporary increase in tidal power is channeled into a larbehind the dam, holding a large amount of potential ene
• With the receding tide, this energy is then converted int
mechanical energy as the water is released through larg
that create electrical power though the use of generator
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III. TIDAL POWER
• TIDAL BARRAGE
The Rance Tidal Power Station, a tidal barrage in France
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III. TIDAL POWER
• TIDAL BARRAGE
Tidal barrages have a lot in common with dams for traditional hydro power, the
resource availability and patterns are the same as for tidal streams.
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III. TIDAL POWER
• TIDAL BARRAGE• Ebb Generation
• While the tide is rising, the reservoir behind the dam
water through open sluices.
• The gate to the turbine is closed. When high tide is re
sluices are shut.
• Once sea level has receded to sufficiently low levels, gate is opened and the water from the reservoir chan
the turbine.
• Due to low head (
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III. TIDAL POWER
• TIDAL BARRAGE
• Flood Generation
• While the tide is rising, water flows through the turbi
reservoir, generating electricity during flood.
• Less efficient than ebb generation.
• Pumping
• In combination with ebb generation, use surplus grid
pump additional water into the reservoir, similar to h
storage.
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III. TIDAL POWER
• TIDAL BARRAGE
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III. TIDAL POWER
• DYNAMIC TIDAL POWER
• Dynamic tidal power (or DTP) is an untried but promising
that would exploit an interaction between potential and k
energies in tidal flows.
• It proposes that very long dams (for example: 30 –50 km l
built from coasts straight out into the sea or ocean, witho
an area.
• Tidal phase differences are introduced across the dam, le
significant water-level differential in shallow coastal seas
strong coast-parallel oscillating tidal currents such as foun
China and Korea.
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III. TIDAL POWER
• DYNAMIC TIDAL POWER
Top-down view of a DTP dam. Blue and dark red colors indicate low and high tide
respectively
http://www.youtube.com/watch?v=vzm0zkxBNZw
http://www.youtube.com/watch?v=vzm0zkxBNZwhttp://www.youtube.com/watch?v=vzm0zkxBNZw
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IV. WAVE POWER
•
Wave Power• The power from surface waves.
• Wave energy
• It is the transport of energy by ocean surface waves, an
capture of that energy to do useful work – for example,generation, water desalination, or the pumping of wate
reservoirs).
• Machinery able to exploit wave power is generally kn
wave energy converter (WEC).
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IV. WAVE POWER
• Physical Concepts• Waves are generated by wind passing over the surface o
• As long as the waves propagate slower than the wind sp
above the waves, there is an energy transfer from the w
waves.
• Both air pressure differences between the upwind and tof a wave crest, as well as friction on the water surface b
making the water to go into the shear stress causes the
the waves.
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IV. WAVE POWER
• Physical Concepts (cont’d.)• Wave height is determined by wind speed
duration of time the wind has been blowi
(the distance over which the wind excites
waves) and by the depth and topography
seafloor (which can focus or disperse the
of the waves).
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IV. WAVE POWER
• Physical Concepts (cont’d.)
When an object bobs up and down on a
ripple in a pond, it experiences an elliptical
trajectory.
Motion of a particle in an ocean wave.
A = At deep water. The orbital motion of
decreases rapidly with increasing depth b
B = At shallow water (ocean floor is now
movement of a fluid particle flattens with
1 = Propagation direction.
2 = Wave crest.
3 = Wave trough
IV WAVE POWER
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IV. WAVE POWER
• Physical Concepts (cont’d.)
• A given wind speed has a matching practical limit over wh
distance will not produce larger waves.
• When this limit has been reached the sea is said to be "fu
developed".
• In general, larger waves are more powerful but wave pow
determined by wave speed, wavelength, and water densit
• Oscillatory motion is highest at the surface and diminishe
exponentially with depth.
• However, for standing waves (clapotis) near a reflecting c
energy is also present as pressure oscillations at great dep
producing microseisms.
IV. WAVE POWER
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• Physical Concepts (cont’d.)
• These pressure fluctuations at greater depth are too sma
interesting from the point of view of wave power.
• The waves propagate on the ocean surface, and the wav
also transported horizontally with the group velocity.
• The mean transport rate of the wave energy through a v
of unit width, parallel to a wave crest, is called the wave (or wave power, which must not be confused with the ac
generated by a wave power device).
IV WAVE POWER
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IV. WAVE POWER
• Wave power formula
In deep water where the water depth is larger than half the wavelengenergy flux is
with: P the wave energy flux per unit of wave-crest length,
H m0 the significant wave height,
T the wave period,
ρ the water density and
g the acceleration by gravity.
The above formula states that wave power is proportional to the wave period and
the wave height. When the significant wave height is given in meters, and the wav
seconds, the result is the wave power in kilowatts (kW) per meter of wavefront len
IV. WAVE POWER
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• Example Problem No. 1: Consider moderate ocean swells, in deep water, a few km o
with a wave height of 3 m and a wave period of 8 seconds. Using the formula to solv
we get
meaning there are 36 kilowatts of power potential per meter of wave crest.
In major storms, the largest waves offshore are about 15 meters high and have a pe
15 seconds. According to the above formula, such waves carry about 1.7 MW of pometer of wavefront.
An effective wave power device captures as much as possible of the wave energy fl
the waves will be of lower height in the region behind the wave power device.
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V. OCEAN THERMAL ENERGY
•
Ocean Thermal Energy Conversion (OTEC)• Ocean Thermal Energy Conversion uses the temperature
between cooler deep and warmer shallow or surface oce
to run a heat engine and produce useful work, usually in
electricity.
•
However, the temperature differential is small and this imeconomic feasibility of ocean thermal energy for electric
generation.
• The most commonly used heat cycle for OTEC is the Ran
using a low-pressure turbine.
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V. OCEAN THERMAL ENERGY
•
Ocean Thermal Energy Conversion (cont’d.)• Systems may be either closed-cycle or open-cycle.
• Closed-cycle engines use a working fluids that are typi
thought of as refrigerants such as ammonia or R-134a
• Open-cycle engines use vapour from the seawater itse
working fluid.• OTEC can also supply quantities of cold water as a by-pro
can be used for air conditioning and refrigeration and the
deep ocean water can feed biological technologies. Anoth
product is fresh water distilled from the sea.
V OCEAN THERMAL ENERGY
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V. OCEAN THERMAL ENERGY
• OTEC Diagram and Applications
http://www.youtube.com/watch?v=aQmfRNz
V OCEAN THERMAL ENERGY
http://www.youtube.com/watch?v=aQmfRNzLNQshttp://www.youtube.com/watch?v=aQmfRNzLNQs
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V. OCEAN THERMAL ENERGY
• History•
1880s, attempts to develop and refine OTEC statrted. Jacqd'Arsonval, a French physicist, proposed tapping the ther
of the ocean.
• 1930, D'Arsonval's student, Georges Claude, built the first
plant, in Matanzas, Cuba. The system generated 22 kW of
with a low-pressure turbine.• In 1935, Claude constructed a plant aboard a 10,000-ton
moored off the coast of Brazil. Weather and waves destro
before it could generate net power. (Net power is the am
power generated after subtracting power needed to run t
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V. OCEAN THERMAL ENERGY
• History (cont’d.)
• In 1956, French scientists designed a 3 MW plant for Ab
d'Ivoire. The plant was never completed, because new f
large amounts of cheap petroleum made it uneconomic
•
In 1962, J. Hilbert Anderson and James H. Anderson, Jr. fincreasing component efficiency. They patented their ne
cycle" design in 1967.
V OCEAN THERMAL ENERGY
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V. OCEAN THERMAL ENERGY
• History (cont’d.)
• Beginning in 1970 the Tokyo Electric Power Company su
built and deployed a 100 kW closed-cycle OTEC plant onof Nauru. The plant became operational on 14 October
producing about 120 kW of electricity; 90 kW was used t
the plant and the remaining electricity was used to pow
and other places. This set a world record for power outp
OTEC system where the power was sent to a real power Currently, the Institute of Ocean Energy, Saga University,
leader and focuses on the power cycle and many of the
benefits.
V. OCEAN THERMAL ENERGY
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• History (cont’d.)
• The United States became involved in
1974, establishing the Natural EnergyLaboratory of Hawaii Authority at
Keahole Point on the Kona coast of
Hawaiʻi. Hawaii is the best US OTEC
location, due to its warm surface water,
access to very deep, very cold water,and high electricity costs. The
laboratory has become a leading test
facility for OTEC technology.View of a land based OTE
Point on the Kona coast of
Department of Energy)
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V. OCEAN THERMAL ENERGY
• History (cont’d.)
• India built a one-MW floating OTEC pilot plant n
Nadu, and its government continues to sponsor
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• Thermodynamic efficiency
• A heat engine gives greater efficiency when run with a lar
temperature difference. In the oceans the temperature dbetween surface and deep water is greatest in the tropics
still a modest 20 to 25 °C.
• It is therefore in the tropics that OTEC offers the greatest
possibilities. OTEC has the potential to offer global amoun
energy that are 10 to 100 times greater than other oceanoptions such as wave power.
• OTEC plants can operate continuously providing a base lo
for an electrical power generation system.
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• Thermodynamic efficiency (cont’d.)
• The main technical challenge of OTEC is to generate
amounts of power efficiently from small temperatur
differences. It is still considered an emerging technol
• Early OTEC systems were 1 to 3 % thermally efficient
below the theoretical maximum 6 and 7 % for this te
difference.• Modern designs allow performance approaching the
theoretical maximum Carnot efficiency and the large
1999 by the USA generated 250 kW.
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V. OCEAN THERMAL ENERGY
• Cycle types
•
Cold seawater is an integral part of each of the three typsystems: closed-cycle, open-cycle, and hybrid.
• To operate, the cold seawater must be brought to the su
primary approaches are active pumping and desalination
Desalinating seawater near the sea floor lowers its densi
causes it to rise to the surface.• The alternative to costly pipes to bring condensing cold w
surface is to pump vaporized low boiling point fluid into
to be condensed, thus reducing pumping volumes and re
technical and environmental problems and lowering cost
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• Closed Cycle System• Closed-cycle systems use fluid with a low boiling poi
ammonia, to power a turbine to generate electricity
• Warm surface seawater is pumped through a heat e
vaporize the fluid. The expanding vapor turns the tugenerator. Cold water, pumped through a second he
exchanger, condenses the vapor into a liquid, which
recycled through the system.
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•
Closed Cycle System (cont’d.)• In 1979, the Natural Energy Laboratory and sever
sector partners developed the "mini OTEC" exper
which achieved the first successful at-sea product
electrical power from closed-cycle OTEC. The min
vessel was moored 1.5 miles (2.4 km) off the Hawand produced enough net electricity to illuminate
light bulbs and run its computers and television.
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• Diagram of a closed cycle OTEC plant
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• Open Cycle System
• Open-cycle OTEC uses warm surface water directly to m
electricity. Placing warm seawater in a low-pressure con
causes it to boil.
• In some schemes, the expanding steam drives a low-pre
turbine attached to an electrical generator. The steam, wleft its salt and other contaminants in the low-pressure c
pure fresh water. It is condensed into a liquid by exposu
temperatures from deep-ocean water. This method prod
desalinized fresh water, suitable for drinking water or irr
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V. OCEAN THERMAL ENERGY
•
Open Cycle System (cont’d.)• In other schemes, the rising steam is used in a gas lif
of lifting water to significant heights. Depending on t
embodiment, such steam lift pump techniques gene
from a hydroelectric turbine either before or after th
used.
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• Diagram of an open cycle OTEC plant
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• Hybrid• A hybrid cycle combines the features of the closed- and
systems.
• In a hybrid, warm seawater enters a vacuum chamber a
evaporated, similar to the open-cycle evaporation proce
• The steam vaporizes the ammonia working fluid of a clo
loop on the other side of an ammonia vaporizer.
• The vaporized fluid then drives a turbine to produce elec
steam condenses within the heat exchanger and provide
desalinated water.
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V. OCEAN THERMAL ENERGY
• Working Fluids• A popular choice of working fluid is ammonia, which has
transport properties, easy availability, and low cost. Amm
however, is toxic and flammable.
• Fluorinated carbons such as CFCs and HCFCs are not toxi
flammable, but they contribute to ozone layer depletion
• Hydrocarbons too are good candidates, but they are high
flammable; in addition, this would create competition fo
them directly as fuels.
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• Working Fluids (cont’d.)
• The power plant size is dependent upon the vapor press
working fluid.
• With increasing vapor pressure, the size of the turbine a
exchangers decreases while the wall thickness of the pipexchangers increase to endure high pressure especially o
evaporator side.
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ENVIRONMENTAL IMPACT
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ENVIRONMENTAL IMPACT
• In the area of air quality, ocean power has less impact th
other forms of electricity generation. Once the devices a
they produce electricity without emissions.
• Concerns about installation, electromagnetic fields, spin
turbines, accidental leaks and changes in currents and w
these could alter migration paths, transform beaches aninjure marine life, disturb the seabed and diminish food a
ENVIRONMENTAL IMPACT
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• Impacts to aquatic ecosystems will occur during installation
operation of OTC projects. Installation involves placement o
generating units, mooring cables or anchors, and electrical tcables to shore.
• Possible operational environmental issues include alteration
ocean currents and waves, alteration of bottom substrates a
sediment transport/deposition, impacts of noise and electro
fields, chemical toxicity, and interference with animal movemigrations.
• Designs that incorporate moving rotors or structures (tidal s
river technologies, some wave technologies) pose the poten
injury to aquatic organisms from strike or impingement.
ENVIRONMENTAL IMPACT
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ENVIRONMENTAL IMPACT
• Environmental evaluations are expected to focus primarily from deployment of large numbers of units, as well as the c
effects of developments when added to existing stresses on
systems.
• For example, impacts to bottom habitats, hydrology, or u
noise levels that are minor for one or a few units may besignificant for large energy farms.
ENVIRONMENTAL IMPACT
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ENVIRONMENTAL IMPACT
• OTC• Carbon dioxide dissolved in deep cold and high pressure l
brought up to the surface and released as the water warm
• Mixing of deep ocean water with shallower water brings
and makes them available to shallow water life. This may
advantage for aquaculture of commercially important spe
may also unbalance the ecological system around the pow
• OTC technologies will include impacts more akin to those
electric plants: alteration of water temperatures, entrainm
impingement.
OCEAN THERMAL ENERGY
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OCEAN THERMAL ENERGY
• Other Risks• Wave power projects can face public resistance to installi
equipment along coastlines.
• Equipment on the ocean floor can also interfere with sed
• Thus far, even wave energy is not yet economically compe
situation is likely to change over time, however, as resear
testing moves the technology forward.• The early risks of ocean technology are likely to be financ
with venture capital, corporate investment and governme
riding on finding the “right” product to access the oceans
REFERENCES
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• Textbooks• Renewable Energy Technologies, Jean-Claude Sabonnadiere, 2009
• Energy Conversion, D. Yogi Goswami, Frank Kreith, 2008
• Power Plant Engineering, 3rd Edition, PK Nag, 2008, Tata McGraw Hill
• Web• http://en.wikipedia.org/wiki/Marine_energy
• http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent
• http://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
• http://en.wikipedia.org/wiki/Wave_power
• http://en.wikipedia.org/wiki/Ocean_thermal_energy
• http://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-
effects-of-oceantidalstream-power
• Youtube Videos• http://www.youtube.com/watch?v=x59MptHscxY
• http://www.youtube.com/watch?v=lfrWE61EeQY
http://en.wikipedia.org/wiki/Tonne_of_oil_equivalenthttp://en.wikipedia.org/wiki/Tonne_of_oil_equivalenthttp://en.wikipedia.org/wiki/Tonne_of_oil_equivalenthttp://en.wikipedia.org/wiki/Tonne_of_oil_equivalenthttp://en.wikipedia.org/wiki/Ocean_thermal_energy_conversionhttp://en.wikipedia.org/wiki/Ocean_thermal_energy_conversionhttp://en.wikipedia.org/wiki/Wave_powerhttp://en.wikipedia.org/wiki/Wave_powerhttp://en.wikipedia.org/wiki/Ocean_thermal_energyhttp://en.wikipedia.org/wiki/Ocean_thermal_energyhttp://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-effects-of-oceantidalstream-powerhttp://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-effects-of-oceantidalstream-powerhttp://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-effects-of-oceantidalstream-powerhttp://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-effects-of-oceantidalstream-powerhttp://www.youtube.com/watch?v=x59MptHscxYhttp://www.youtube.com/watch?v=x59MptHscxYhttp://www.youtube.com/watch?v=lfrWE61EeQYhttp://www.youtube.com/watch?v=lfrWE61EeQYhttp://www.youtube.com/watch?v=lfrWE61EeQYhttp://www.youtube.com/watch?v=x59MptHscxYhttp://www.renewableenergyworld.com/rea/blog/post/2011/03/understanding-the-effects-of-oceantidalstream-powerhttp://en.wikipedia.org/wiki/Ocean_thermal_energyhttp://en.wikipedia.org/wiki/Wave_powerhttp://en.wikipedia.org/wiki/Ocean_thermal_energy_conversionhttp://en.wikipedia.org/wiki/Tonne_of_oil_equivalenthttp://en.wikipedia.org/wiki/Tonne_of_oil_equivalent