TIDAL and WAVE POWER

TIDAL & WAVE
POWER
University of CanberraUniversity of Canberra
July 2007July 2007
byby
AshuriAshuri
GunoroGunoro
Presented in Professional ManagementPresented in Professional Management
ProgramProgram

1. Tidal Power1. Tidal Power
Tidal powerTidal power, sometimes called, sometimes called tidal energytidal energy, is a form of, is a form of hydropowerhydropower thatthat
exploits the rise and fall in sea levels due to theexploits the rise and fall in sea levels due to the tidestides, or the movement of, or the movement of
water caused by the tidal flow. Because thewater caused by the tidal flow. Because the tidal forcestidal forces are caused byare caused by
interaction between theinteraction between the gravitygravity of theof the EarthEarth,, MoonMoon andand SunSun, tidal power is, tidal power is
essentially inexhaustible and classified as aessentially inexhaustible and classified as a renewable energyrenewable energy source.source.
Although not yet widely used, tidal power has great potential for futureAlthough not yet widely used, tidal power has great potential for future
electricity generationelectricity generation and is more predictable thanand is more predictable than wind energywind energy andand
solar powersolar power. In Europe,. In Europe, tide millstide mills have been used for nearly a thousandhave been used for nearly a thousand
years, mainly for grinding grains.years, mainly for grinding grains.
Tidal power can be classified into two types. Tidal stream systems makeTidal power can be classified into two types. Tidal stream systems make
use of theuse of the kinetic energykinetic energy from the moving water currents to power turbines,from the moving water currents to power turbines,
in a similar way to underwaterin a similar way to underwater wind turbineswind turbines. This method is gaining in. This method is gaining in
popularity because of the lower ecological impact compared to the secondpopularity because of the lower ecological impact compared to the second
type of system, the barrage. Barrages make use of thetype of system, the barrage. Barrages make use of the potential energypotential energy
from the difference in height (orfrom the difference in height (or headhead) between high and low tides, and) between high and low tides, and
their use is better established.their use is better established.

Modern advance in turbine technology may eventually see large amountsModern advance in turbine technology may eventually see large amounts
of power generated from the oceans using the tidal stream designs.of power generated from the oceans using the tidal stream designs.
Arrayed in high velocity areas where natural flows are concentrated suchArrayed in high velocity areas where natural flows are concentrated such
as the west coast of Canada, the Strait of Gibraltar, the Bosporus, andas the west coast of Canada, the Strait of Gibraltar, the Bosporus, and
numerous sites in south east Asia and Australia. Such flows occur almostnumerous sites in south east Asia and Australia. Such flows occur almost
anywhere where there are entrances to bays and rivers, or between landanywhere where there are entrances to bays and rivers, or between land
masses where water currents are concentrated.masses where water currents are concentrated.
A factor in human settlement geography is water. Human settlements haveA factor in human settlement geography is water. Human settlements have
often started around bays rivers and lakes. Future settlement may beoften started around bays rivers and lakes. Future settlement may be
concentrated around moving water, allowing communities to powerconcentrated around moving water, allowing communities to power
themselves with non-polluting energy from moving water.themselves with non-polluting energy from moving water.

A relatively new technology tidal stream generators draw energy from
currents in much the same way as wind turbines. The higher density of
water, some 832 times the density of air, means that a single generator
can provide significant power.
Even more so than with wind power, selection of location is critical for a
tidal stream power generator. Tidal stream systems need to be located in
areas with fast currents where natural flows are concentrated between
obstructions, for example at the entrances to bays and rivers, around
rocky points, headlands, or between islands or other land masses. The
following potential sites have been suggested:
1.1 Tidal stream power1.1 Tidal stream power
• The Pentland Firth in Scotland
• The Channel Islands in the United Kingdom
• The Cook Straits in New Zealand
• The Strait of Gibraltar
• The Bosporus in Turkey
• The Bass Strait in Australia
• The Torres Strait in Australia
• The Strait of Malacca between Indonesia and Singapore
• The Bay of Fundy in Canada.

Several prototypes have shown promise. Trials in the Strait of Messina,
Italy, started in 2001[1] and an Australian company <http://
tidalenergy.net.au/> undertook successful commercial trials of highly
efficient shrouded turbines on the Gold Coast, Queensland in 2002 that
was followed by successful joint venture commercial trials by Canada by
Quantum Hydro Power in 2005-2006 using the Gorlov Helical Turbine on
the Canadian West Coast where water speeds have been measured up
to 16 knots. These small 2-4 meter diameter highly efficient shrouded
turbines, considered to be the next generation in design, are capable of
100 kW - 200kW in 6 - 10 knots of water speed commonly available in
many of the Western Canadian regions waterways.
PrototypesPrototypes

One of the Sea Generators awaiting installation in Strangford Lough

During 2003 a 300 kW Periodflow marine current propeller type turbine was
tested off the coast of Devon, England, and a 150 kW oscillating hydroplane
device, the Stingray, was tested off the Scottish coast. Another British
device, the Hydro Venturi, is to be tested in San Francisco Bay.[citation
needed]
Although still a prototype, the world's first grid-connected turbine, generating
300 kW, started generation November 13, 2003, in the Kvalsund, south of
Hammerfest, Norway, with plans to install a further 19 turbines.[2][3]
The world's first commercial prototype will be installed by
Marine Current Turbines Ltd in Strangford Lough in Northern Ireland in
September 2007. The turbine will generate 1.2MW and be connected to the
grid.

Tidal systems do not interfere with fish migration at times of spawning,
since the water remains open. As water current turbines typically turn
very slowly at around 20-30 r.p.m., fish are able to safely navigate either
past or through the turbines, drastically reducing or eliminating fish kills
compared to barrage systems.
Environmental impactEnvironmental impact
The energy available from these kinetic systems can be expressed as:The energy available from these kinetic systems can be expressed as:
P = Cp x 0.5 x ρ x A x V3P = Cp x 0.5 x ρ x A x V3
Where:Where:
Cp is the turbine coefficient of performanceCp is the turbine coefficient of performance
P = the power generated (in kW)P = the power generated (in kW)
ρ = the density of the water (seawater is 1025 kg per cubic meter)ρ = the density of the water (seawater is 1025 kg per cubic meter)
A = the sweep area of the turbine (in m2)A = the sweep area of the turbine (in m2)
V3 = the velocity of the flow cubed (i.e. V x V x V)V3 = the velocity of the flow cubed (i.e. V x V x V)
Relative to an open turbine in free stream. Shrouded turbines areRelative to an open turbine in free stream. Shrouded turbines are
capable of higher efficiencies as much as 4 times the power of the samecapable of higher efficiencies as much as 4 times the power of the same
turbine in open flow.turbine in open flow.
Energy calculationsEnergy calculations

The barrage method of extracting tidal energy involves building a
barrage and creating a tidal lagoon. The barrage traps a water level
inside a basin. Head (a height of water pressure) is created when the
water level outside of the basin or lagoon changes relative to the water
level inside. The head is used to drive turbines. The
largest such installation has been working on the Rance river, France,
since 1967 with an installed (peak) power of 240 MW, and an annual
production of 600 GWh (about 68 MW average power)
1.2 Barrage tidal power1.2 Barrage tidal power
• An artistic impression of a tidal barrage, including embankments, a ship
lock and caissons housing a sluice and two turbines.

Artist's impression of theArtist's impression of the Severn BarrageSevern Barrage and road link proposed in 1989.and road link proposed in 1989.
The scheme would have generated 6% of theThe scheme would have generated 6% of the UK'sUK's electricity supplyelectricity supply

The basic elements of a barrage are caissons, embankments, sluices,
turbines and ship locks. Sluices, turbines and ship locks are housed in
caisson (very large concrete blocks). Embankments seal a basin where it
is not sealed by caissons.
The sluice gates applicable to tidal power are the flap gate, vertical rising
gate, radial gate and rising sector.
Barrage systems are sometimes affected by problems of high civil
infrastructure costs associated with what is in effect a dam being placed
across two estuarine systems, and the environmental problems associated
with changing a large ecosystem.

The basin is filled through the sluices until high tide. Then the sluiceThe basin is filled through the sluices until high tide. Then the sluice
gates are closed. (At this stage there may be "Pumping" to raise the levelgates are closed. (At this stage there may be "Pumping" to raise the level
further). The turbine gates are kept closed until the sea level falls tofurther). The turbine gates are kept closed until the sea level falls to
create sufficient head across the barrage, and then are opened so thatcreate sufficient head across the barrage, and then are opened so that
the turbines generate until the head is again low. Then the sluices arethe turbines generate until the head is again low. Then the sluices are
opened, turbines disconnected and the basin is filled again. The cycleopened, turbines disconnected and the basin is filled again. The cycle
repeats itself. Ebb generation (also known as outflow generation) takesrepeats itself. Ebb generation (also known as outflow generation) takes
its name because generation occurs as the tide ebbs.its name because generation occurs as the tide ebbs.
Modes of operationModes of operation
Ebb generationEbb generation
The basin is filled through the turbines, which generate at tide flood. ThisThe basin is filled through the turbines, which generate at tide flood. This
is generally much less efficient than ebb generation, because the volumeis generally much less efficient than ebb generation, because the volume
contained in the upper half of the basin (which is where ebb generationcontained in the upper half of the basin (which is where ebb generation
operates) is greater than the volume of the lower half (and making theoperates) is greater than the volume of the lower half (and making the
difference in levels between the basin side and the sea side of thedifference in levels between the basin side and the sea side of the
barrage), (and therefore the available potential energy) less than it wouldbarrage), (and therefore the available potential energy) less than it would
otherwise be. This is not a problem with the "lagoon" model; the reasonotherwise be. This is not a problem with the "lagoon" model; the reason
being that there is no current from a river to slow the flooding currentbeing that there is no current from a river to slow the flooding current
from the sea.from the sea.
Flood generationFlood generation

Turbines are able to be powered in reverse by excess energy in the gridTurbines are able to be powered in reverse by excess energy in the grid
to increase the water level in the basin at high tide (for ebb generation).to increase the water level in the basin at high tide (for ebb generation).
This energy is more than returned during generation, because powerThis energy is more than returned during generation, because power
output is strongly related to the head.output is strongly related to the head.
PumpingPumping
With two basins, one is filled at high tide and the other is emptied at lowWith two basins, one is filled at high tide and the other is emptied at low
tide. Turbines are placed between the basins. Two-basin schemes offertide. Turbines are placed between the basins. Two-basin schemes offer
advantages over normal schemes in that generation time can beadvantages over normal schemes in that generation time can be
adjusted with high flexibility and it is also possible to generate almostadjusted with high flexibility and it is also possible to generate almost
continuously. In normal estuarine situations, however, two-basincontinuously. In normal estuarine situations, however, two-basin
schemes are very expensive to construct due to the cost of the extraschemes are very expensive to construct due to the cost of the extra
length of barrage. There are some favourable geographies, however,length of barrage. There are some favourable geographies, however,
which are well suited to this type of scheme.which are well suited to this type of scheme.
Two-basin schemesTwo-basin schemes
The placement of a barrage into an estuary has a considerable effect onThe placement of a barrage into an estuary has a considerable effect on
the water inside the basin and on the fish. A tidal current turbine will havethe water inside the basin and on the fish. A tidal current turbine will have
a much lower impact.a much lower impact.[[
Environmental impactEnvironmental impact

Turbidity (the amount of matter in suspension in the water) decreases asTurbidity (the amount of matter in suspension in the water) decreases as
a result of smaller volume of water being exchanged between the basina result of smaller volume of water being exchanged between the basin
and the sea. This lets light from the Sun to penetrate the water further,and the sea. This lets light from the Sun to penetrate the water further,
improving conditions for theimproving conditions for the phytoplanktonphytoplankton. The changes propagate up. The changes propagate up
thethe food chainfood chain, causing a general change in the, causing a general change in the ecosystemecosystem..
TurbidityTurbidity
As a result of less water exchange with the sea, the average salinityAs a result of less water exchange with the sea, the average salinity
inside the basin decreases, also affecting the ecosystem. "Tidalinside the basin decreases, also affecting the ecosystem. "Tidal
Lagoons" do not suffer from this problem.Lagoons" do not suffer from this problem.
SalinitySalinity
Estuaries often have high volume of sediments moving through them,Estuaries often have high volume of sediments moving through them,
from the rivers to the sea. The introduction of a barrage into an estuaryfrom the rivers to the sea. The introduction of a barrage into an estuary
may result in sediment accumulation within the barrage, affecting themay result in sediment accumulation within the barrage, affecting the
ecosystem and also the operation of the barrage.ecosystem and also the operation of the barrage.
Sediment movementsSediment movements

Again, as a result of reduced volume, the pollutants accumulating in theAgain, as a result of reduced volume, the pollutants accumulating in the
basin may be less efficiently dispersed, so their concentrations maybasin may be less efficiently dispersed, so their concentrations may
increase. Forincrease. For biodegradablebiodegradable pollutants, such aspollutants, such as sewagesewage, an increase in, an increase in
concentration is likely to lead to increased bacteria growth in the basin,concentration is likely to lead to increased bacteria growth in the basin,
having impacts on the health of the human community and thehaving impacts on the health of the human community and the
ecosystem.ecosystem.
PollutantsPollutants
Fish may move through sluices safely, but when these are closed, fishFish may move through sluices safely, but when these are closed, fish
will seek out turbines and attempt to swim through them. Also, some fishwill seek out turbines and attempt to swim through them. Also, some fish
will be unable to escape the water speed near a turbine and will bewill be unable to escape the water speed near a turbine and will be
sucked through. Even with the most fish-friendly turbine design, fishsucked through. Even with the most fish-friendly turbine design, fish
mortality per pass is approximately 15% (from pressure drop, contactmortality per pass is approximately 15% (from pressure drop, contact
with blades,with blades, cavitationcavitation, etc.). This can be acceptable for a, etc.). This can be acceptable for a spawning runspawning run,,
but is devastating for local fish who pass in and out of the basin on abut is devastating for local fish who pass in and out of the basin on a
daily basis. Alternative passage technologies (daily basis. Alternative passage technologies (fish laddersfish ladders, fish lifts, etc.), fish lifts, etc.)
have so far failed to solve this problem for tidal barrages, either offeringhave so far failed to solve this problem for tidal barrages, either offering
extremely expensive solutions, or ones which are used by a smallextremely expensive solutions, or ones which are used by a small
fraction of fish only. Research in sonic guidance of fish is ongoing.fraction of fish only. Research in sonic guidance of fish is ongoing.
FishFish

The energy available from barrage is dependant on the volume of water.The energy available from barrage is dependant on the volume of water.
TheThe potential energypotential energy contained in a volume of water is :contained in a volume of water is :
Energy calculationsEnergy calculations
A barrage is therefore best placed in a location with very high-amplitudeA barrage is therefore best placed in a location with very high-amplitude
tides. Suitable locations are found intides. Suitable locations are found in RussiaRussia,, USAUSA,, CanadaCanada,, AustraliaAustralia,,
KoreaKorea, the, the UKUK and elsewhere. Amplitudes of up to 17 m (56 ft) occur forand elsewhere. Amplitudes of up to 17 m (56 ft) occur for
example in theexample in the Bay of FundyBay of Fundy, where, where tidal resonancetidal resonance amplifies the tidalamplifies the tidal
waves.waves.
where:
x : is the height of the tide
M : is the mass of water
g : is the acceleration due to gravity at the Earth's surface.
xMgE =

Tidal barrage power schemes have a high capital cost and a very lowTidal barrage power schemes have a high capital cost and a very low
running cost. As a result, a tidal power scheme may not produce returnsrunning cost. As a result, a tidal power scheme may not produce returns
for years, and investors are thus reluctant to participate in such projects.for years, and investors are thus reluctant to participate in such projects.
Governments may be able to finance tidal barrage power, but many areGovernments may be able to finance tidal barrage power, but many are
unwilling to do so also due to the lag time before investment return andunwilling to do so also due to the lag time before investment return and
the high irreversible commitment. For example thethe high irreversible commitment. For example the
energy policy of the United Kingdomenergy policy of the United Kingdom[4][4] recognizes the role of tidal energyrecognizes the role of tidal energy
and expresses the need for local councils to understand the broaderand expresses the need for local councils to understand the broader
national goals of renewable energy in approving tidal projects. The UKnational goals of renewable energy in approving tidal projects. The UK
government itself appreciates the technical viability and sitting optionsgovernment itself appreciates the technical viability and sitting options
available, but has failed to provide meaningful incentives to move itsavailable, but has failed to provide meaningful incentives to move its
goals forward.goals forward.
EconomicsEconomics
Tidal power schemes do not produce energy all day. A conventionalTidal power schemes do not produce energy all day. A conventional
design, in any mode of operation, would produce power for 6 to 12 hoursdesign, in any mode of operation, would produce power for 6 to 12 hours
in every 24 and will not produce power at other times. As the tidal cycle isin every 24 and will not produce power at other times. As the tidal cycle is
based on the rotation of the Earth with respect to the moon (24.8 hours),based on the rotation of the Earth with respect to the moon (24.8 hours),
and the demand for electricity is based on the period of rotation of theand the demand for electricity is based on the period of rotation of the
earth (24 hours), the energy production cycle will not always be in phaseearth (24 hours), the energy production cycle will not always be in phase
with the demand cycle.with the demand cycle.
Variable nature of power outputVariable nature of power output

Mathematical modelling of tidal schemesMathematical modelling of tidal schemes
In mathematical modelling of a scheme design, the basin is broken intoIn mathematical modelling of a scheme design, the basin is broken into
segments, each maintaining its own set of variables. Time is advanced in steps.segments, each maintaining its own set of variables. Time is advanced in steps.
Every step, neighbouring segments influence each other and variables areEvery step, neighbouring segments influence each other and variables are
updated.updated.
In these models, the basin is broken into large segments (1D), squares (2D) orIn these models, the basin is broken into large segments (1D), squares (2D) or
cubes (3D). The complexity and accuracy increases with dimension.cubes (3D). The complexity and accuracy increases with dimension.
Mathematical modelling produces quantitative information for a range ofMathematical modelling produces quantitative information for a range of
parameters, including:parameters, including:
• Water levels (during operation, construction, extreme conditions, etc.)Water levels (during operation, construction, extreme conditions, etc.)
• CurrentsCurrents
• WavesWaves
• Power outputPower output
• TurbidityTurbidity
• SalinitySalinity
• Sediment movementsSediment movements

Tidal energy has an efficiency of 80% in converting the potential energyTidal energy has an efficiency of 80% in converting the potential energy
of the water into electricity,of the water into electricity,[[citationcitation neededneeded]] which is efficient comparedwhich is efficient compared
to other energy resources such asto other energy resources such as solar powersolar power oror fossil fuel power plantsfossil fuel power plants..
Energy efficiencyEnergy efficiency
A tidal power scheme is a long-term source of electricity. A proposal forA tidal power scheme is a long-term source of electricity. A proposal for
thethe Severn BarrageSevern Barrage, if built, has been projected to save 18 million tons of, if built, has been projected to save 18 million tons of
coalcoal per year of operation. This decreases the output ofper year of operation. This decreases the output of
greenhouse gasesgreenhouse gases into the atmosphere.into the atmosphere.
Global environmental impactGlobal environmental impact
If fossil fuel resource is likely to decline during the 21st, as predicted byIf fossil fuel resource is likely to decline during the 21st, as predicted by
HubbertHubbert peak theorypeak theory, tidal power is one of the alternative source of, tidal power is one of the alternative source of
energy that will need to be developed to satisfy the human demand forenergy that will need to be developed to satisfy the human demand for
energy.energy.

Operating tidal power schemesOperating tidal power schemes
Resource around the worldResource around the world
• The first tidal power station was the Rance tidal power plant built over a period of 6
years from 1960 to 1966 at La Rance, France.[5] It has 240MW installed capacity.
• The first (and only) tidal power site in North America is the
Annapolis Royal Generating Station, Annapolis Royal, Nova Scotia, which opened
in 1984 on an inlet of the Bay of Fundy.[6] It has 20MW installed capacity.
• A small project was built by the Soviet Union at Kislaya Guba on the Barents Sea. It
has 0.5MW installed capacity.
• China has apparently developed several small tidal power projects and one large
facility in Jiangxia.
• China is also developing a tidal lagoon near the mouth of the Yalu.[7]
• Scotland has committed to having 18% of its power from green sources by 2010,
including 10% from a tidal generator. The British government says this will replace
one huge fossil fueled power station.[8]
• South African energy parastatal Eskom is investigating using the
Mozambique Current to generate power off the coast of KwaZulu Natal. Because
the continental shelf is near to land it may be possible to generate electricity by
tapping into the fast flowing Mozambique current.

Tidal power schemes being consideredTidal power schemes being considered
In the table,
'-' indicates missing
information,
'?' indicates
information which
has not been
decided
Country Place
Mean tidal range
(m)
Area of basin
(km²)
Maximum
capacity (MW)
Argentina San Jose 5.9 - 6800
Australia Secure Bay 10.9 - ?
Canada
Cobequid 12.4 240 5338
Cumberland 10.9 90 1400
Shepody 10.0 115 1800
Passamaquoddy 5.5 - ?
India
Kutch 5.3 170 900
Cambay 6.8 1970 7000
Korea
Garolim 4.7 100 480
Cheonsu 4.5 - -
Mexico
Rio Colorado 6 -7 - ?
Tiburon - - ?
United Kingdom
Severn 7.8 450 8640
Mersey 6.5 61 700
Strangford Lough - - -
Conwy 5.2 5.5 33
United States
Passamaquoddy 5.5 - ?
Knik Arm 7.5 - 2900
Turnagain Arm 7.5 - 6501
Russia
Mezen 9.1 2300 19200
Tugur - - 8000
Penzhinskaya Bay 6.0 - 87000
South Africa Mozambique Channel ? ? ?

Introduction
The tide moves a huge amount of
water twice each day, and
harnessing it could provide a great
deal of energy - around 20% of
Britain's needs.
Although the energy supply is
reliable and plentiful, converting it
into useful electrical power is not
easy.
There are eight main sites around
Britain where tidal power stations
could usefully be built, including the
Severn, Dee, Solway and Humber
estuaries.
Only around 20 sites in the world
have been identified as possible tidal
power stations.

How it works: Tidal Barrages
These work rather like a hydro-electric
scheme, except that the dam is much
bigger.
A huge dam (called a "barrage") is built
across a river estuary. When the tide goes
in and out, the water flows through tunnels
in the dam.
The ebb and flow of the tides can be used to
turn a turbine, or it can be used to push air
through a pipe, which then turns a turbine.
Large lock gates, like the ones used on
canals, allow ships to pass.

More details
The largest tidal power station in the world
(and the only one in Europe) is in the
Rance estuary in northern France. It was
built in 1966.
A major drawback of tidal power stations is
that they can only generate when the tide is
flowing in or out - in other words, only for
10 hours each day. However, tides are
totally predictable, so we can plan to have
other power stations generating at those
times when the tidal station is out of action.
There have been plans for a "Severn Barrage" from Brean Down in Somerset to Lavernock
Point in Wales. Every now and again the idea gets proposed, but nothing has been built yet.
It may have over 200 large turbines, and provide over 8,000 Megawatts of power (that's over
12 nuclear power station's worth). It would take 7 years to build, and could provide 7% of the
energy needs for England and Wales.
There would be a number of benefits, including protecting a large stretch of coastline against
damage from high storm tides, and providing a ready-made road bridge. However, the drastic
changes to the currents in the estuary could have huge effects on the ecosystem.

offshore turbines
Another option is to use
offshore turbines rather
like an underwater wind
farm.
This has the advantage of
being much cheaper to
build, and does not have
the environmental
problems that a tidal
barrage would bring.
There are also many more
suitable sites.
Find out more about the
world's first offshore tidal
power station at

The University of Wales
Swansea and partners are also
researching techniques to
extract electrical energy from
flowing water.
The "Swanturbines" design is
different to other devices in a
number of ways. The most
significant is that it is direct drive,
where the blades are connected
directly to the electrical generator
without a gearbox between. This
is more efficient and there is no
gearbox to go wrong. Another
difference is that it uses a
"gravity base", a large concrete
block to hold it to the seabed,
rather than drilling into the
seabed. Finally, the blades are
fixed pitch, rather than actively
controlled, this is again to design
out components that could be
unreliable.

2.1 Introduction2.1 Introduction
Ocean waves are caused by the wind asOcean waves are caused by the wind as
it blows across the sea. Waves are ait blows across the sea. Waves are a
powerful source of energy.powerful source of energy.
The problem is that it's not easy toThe problem is that it's not easy to
harness this energy and convert it intoharness this energy and convert it into
electricity in large amounts. Thus, waveelectricity in large amounts. Thus, wave
power stations are rare.power stations are rare.

Wave energy from the wind on the seaWave energy from the wind on the sea

Physical conceptsPhysical concepts
When an object bobs up and down on a ripple in a pond, it
experiences an elliptical trajectory.

WAVE ENERGY MACHINEWAVE ENERGY MACHINE

DESIGN VARIATIONSDESIGN VARIATIONS

Wrist Pin & Roller GearWrist Pin & Roller Gear

General Assembly Gear & FlywheelGeneral Assembly Gear & Flywheel

"Spinner Drive" & Flywheel"Spinner Drive" & Flywheel

Simple Bilge PumpSimple Bilge Pump

Neo-AeroDynamicNeo-AeroDynamic

Oscillating or Assisted Water Columns (OWC), buoys and pontoons (theOscillating or Assisted Water Columns (OWC), buoys and pontoons (the
Hosepump), flaps and tapered channels (the Pendulor and TAPCHAN) stillHosepump), flaps and tapered channels (the Pendulor and TAPCHAN) still
existor continue to be developedexistor continue to be developed

How it worksHow it works
• There are several methods of getting energy from
waves, but one of the most effective works like a
swimming pool wave machine in reverse.
• At a swimming pool, air is blown in and out of a chamber
beside the pool, which makes the water outside bob up
and down, causing waves.
• At a wave power station, the waves arriving cause the
water in the chamber to rise and fall, which means that
air is forced in and out of the hole in the top of the
chamber.

We place a turbine in this holeWe place a turbine in this hole

We place a turbine in this holeWe place a turbine in this hole
• which is turned by the air rushing in and out. The turbine
turns a generator.
• A problem with this design is that the rushing air can be
very noisy, unless a silencer is fitted to the turbine. The
noise is not a huge problem anyway, as the waves make
quite a bit of noise themselves.

More detailsMore details
• Once you've built it, the energy is free, needs no fuel and
produces no waste or pollution.
• One big problem is that of building and anchoring
something that can withstand the roughest conditions at
sea, yet can generate a reasonable amount of power
from small waves. It's not much use if it only works
during storms!

LimpetLimpet
A company called Wavegen now operate a
commercial wave power station called
"Limpet" on the Scottish island of Islay.

LimpetLimpet
(Land-Installed Marine-Powered Energy Transformer)(Land-Installed Marine-Powered Energy Transformer)

View a SimulationView a Simulation

PelamisPelamis
A company called Ocean Power Delivery are developing a
method of offshore wave energy collection, using a floating
tube called "Pelamis".

Pelamis in ExperimentPelamis in Experiment

The pelamisThe pelamis
(named after a sea-snake)(named after a sea-snake)

PelamisPelamis – prototype (Ocean Power Delivery Ltd.)– prototype (Ocean Power Delivery Ltd.)

Pelamis Ready to InstallPelamis Ready to Install

PELAMISPELAMIS
about the size of 5 railway carriagesabout the size of 5 railway carriages

PELAMISPELAMIS
bobs up and down in the waves, as the hinges bend theybobs up and down in the waves, as the hinges bend they
pump hydraulic fluid which drives generators.pump hydraulic fluid which drives generators.

The first prototype was installed at the EuropeanThe first prototype was installed at the European
Marine Energy Centre at Orkney.Marine Energy Centre at Orkney.

The Pelamis on site at the EMECThe Pelamis on site at the EMEC
centre, Orkneycentre, Orkney

Pelamis WavefarmPelamis Wavefarm

DisadvantagesDisadvantages
• Depends on the waves - sometimes you'll get loads of
energy, sometimes nothing.
• Needs a suitable site, where waves are consistently
strong.
• Some designs are noisy.
• Must be able to withstand very rough weather.

Is it renewable?Is it renewable?
• Wave power is renewable.
• Don’t Forget to Remember it !!!!

Thank youThank you
Have an any question ?

TIDAL and WAVE POWER

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