TIDAL ENERGY - ENERGÍA DE LAS MAREAS

TIDAL POWER
ALAN E. SUÁREZ
Energy and Environmental Processes
Processi per l’Energia e l’Ambiente (PEA)
A.A. 2013/2014

PEA_WAVE AND TIDAL ENERGY
2
• To show the sea energy presented in the tides.
• To show how is possible to take advantage of this energy to convert it
in another useful kind of energy (work).
• To show the history in the world of development of this transformation.
• To show the currents plants and projects using tidal energy.
• To show the pros and contras of this renewable energy.
• To show some ideas about new projects using tidal energy, be it for
improve the current technology or for creating new ways to take
advantage of or new uses.
The aim of this presentation is:
SCOPE

3
• Tidal Energy (or Power) is the energy transported by the tides
currents in the ocean in form of mechanical energy.
• It can be converted into
a useful forms of power
(energy), mainly
electricity generation.
What is Tidal energy?
INTRODUCTION

4INTRODUCTION
What is the difference between Waves and Tides?
• Tide is the cyclic rise and fall
of sea level, caused by the
gravitational pulls of the sun
and moon.
• Ocean Wave (or Wind Wave)
is an surface wave generated
by local wind.
Earth land masses also move because of the Moon and Sun pulls,
but it’s not easily to see

5
Percentage for Total World Energy Consumption – Tidal Energy
INTRODUCTION
< 0,00016%
2009 2010
16,7% x 0,001%
= 0,00017 %
2011
19% x 0,001%
= 0,00019 %

6
• Currently: 250 MW approx.
• Potential in ocean currents to produce ca. 450 TW
 1,8 million times current production
 0,00019% x 1 800 000
= 342% of current total world energy consumption!
• But, statistics…
Total World Tidal Energy Production
INTRODUCTION
Source: Energy Information Administration, Annual Energy
Outlook 2013,
http://www.eia.gov/forecasts/aeo/er/pdf/appa.pdf
http://www.eia.gov/forecasts/aeo/er/pdf/tbla17.pdf
http://www.forbes.com

7FUNDAMENTALS
What causes the tides?
• Moon gravitational pulls
• Sun gravitational pulls
• Sun-Moon position relative to
the earth

8
• Sea level rises over several hours, covering the intertidal zone (flood
tide).
• The water rises to its highest level, reaching high tide, and stopping
(slack tidal; slack water).
• Sea level falls over several hours, revealing the intertidal zone (ebb
tide).
• The water stops falling, reaching low tide, and stopping (slack tidal;
slack water).
THESE MOVEMENTS GENERATE CONSTANT TIDAL STREAMS,
WITH A HIGH AMOUNT OF ENERGY
Tide changes
FUNDAMENTALS

9FUNDAMENTALS
What influences tide behavior?
• Offshore and near-shore deep
(bathymetry)
• Coastlines shape
• Declination of the Earth’s orbit
• Declination of the Moon’s orbit
• Presence of land masses
• Speed of the Earth’s rotation
(inertia)
• Coriolis effect on the tide flow
• Frictional forces

10
• Diurnal tides (daily tides):
• 1 high tide – 1 low tide each tidal day
• Unusal
(e.g. Gulf of Mexico)
• Semidiurnal tides (semidaily tides):
• 2 high tides – 2 low tides each tidal day
• Equal tides during each period
• Period of 12 hrs and 24.5 minutes
(e.g. Moon passing through equator)
• Mixed tides:
• 2 high tides – 2 low tides each tidal day
• Unequal tides during each period
Most common type
FUNDAMENTALS
Tides classification I

11
• Spring tides:
Both Sun and Moon pulls in
the same line (syzygy)
• Neap tides:
Moon in quadrature
respect to the sun (90°)
• Metereological tides
(storm surges):
• Wind and barometric
pressure changes
• Shallow seas and
near coasts.
FUNDAMENTALS
Tides classification II

12FUNDAMENTALS
Tides datum
• Reference level
• Vertical datum
• Reference plane
• MLW Spring generally taken
as reference
• Tides can also vary with the
meterological conditions
• Winds
• Pressure

13
• One single tidal constituent represents just one effect (M2: Moon
pull; S2: Sun pull, etc.)
• h t = 𝐴𝑐𝑜𝑠(𝜔𝑡 + ), where 𝐴 =amplitude, 𝜔=frequency, 𝑡=time,
=phase constituent.
• Every place has different tidal constituents factors.
• By adding the different tidal constituents, it’s possible to find the
tidal behavior for each different place (e.g. Ports).
•
Tidal constituents (Tidal Analysis)
FUNDAMENTALS

14
Major Tidal constituents
FUNDAMENTALS
Species
Darwin
Symbol
Speed
rate(°/hr)
Higher
harmonics
Period < 12 h
Shallow water overtides of principal lunar M4 57,97
Shallow water overtides of principal lunar M6 86,95
Shallow water overtides of principal solar S4 60,00
Semi-diurnal
Period < 24 h
Principal lunar semidiurnal M2 28,98
Principal solar semidiurnal S2 30,00
Larger lunar elliptic semidiurnal N2 28,44
Diurnal
Period > 24 h
Lunar diurnal (Luni-solar declinational) K1 15,04
Lunar diurnal (Lunar declinational diurnal) O1 13,94

15
Tide Predicting
Machine
FUNDAMENTALS
CURIOUS FACT:
These machines
were used in the
World War II to
predict the tides
for planning the
invasion of
Normandy.

16FUNDAMENTALS
M2 Tidal Constituent
AMPHIDROMIC
POINT COTIDAL
LINE

17
• Tide Pole (or Tide Staff) Gauges
• Float Gauges
• Thomson type (1887)
Tide measurement (real data)
FUNDAMENTALS

18
• Acoustic Gauges
• Pressure Gauges
• Radar Gauges
• Ultrasonic Gauges
• OTHER USES: Shipping and fishing industries; Tsunami warnings.
Tide measurement (real data)
FUNDAMENTALS

• National Ocean Service (NOS) information:
• For various part of the world, in 4 volumes (+1 for Alaska).
• Each volume:
• Table 1: Tides for Reference stations
• Table 2: Tidal differences and ratios for subordinate stations
• Table 3: Information for tide at any time between HW and LW
• Table 4-5: Sunrise-Sunset for various latitudes and conversions
19
Tides prediction
TIDAL STREAMS

20
• Galileo Galilei (Discorso del flusso e reflusso del mare, 1616 ) 
Earth’s rotation
• Isaac Newton (Principia, 1687)  Gravitational forces
• Pierre-Simon Laplace (1776)  Partial differential equations
• William Thomson (Lord Kelvin; 1860)  Laplace eq. + Curl
component / Fourier analysis / First «Tide predicting machine».
• George Darwin (Tides prediction, 1891)  Best approach –
Harmonic analysis
• Dr. Arthur Thomas Doodson (1921)  Best approach, including
new Lunar theory / 388 tidal frequencies / Doodson-Légé TPM
Tidal Analysis Precursors – Physics
FUNDAMENTALS

21
• Horizontal movement of water, product of the constant and
rhythmic pulls over the oceans, as seen before.
• Depending on the place, and even on the Earth-Moon-Sun position,
they can be stronger or weaker.
• Slack water (stand of the tide)  Unstressed water; no movement
time.
• Spring tide has a speed about
double that of a neap tide. Else
streams are between these two
numbers.
• Spring tides have shorter
slack times than average.
Tidal Streams (Currents)
TIDAL STREAMS

22
• Tidal current: it depends on the rise and fall of the tide.
• Nontidal current: includes currents not due to tidal movement:
• Permanent currents in the general circulatory system
• Temporary currents from meteorological conditions (e.g. wind)
• Real currents are a combination of these both kind of currents.
Tidal and Nontidal Currents
TIDAL STREAMS

23
Major global Nontidal Currents
TIDAL STREAMS

24
• Tidal current is rotary (and slower), when not restricted (offshore)
• Caused by the Earth’s rotation
• Clockwise in the Northern hemisphere; Counterclockwise
in the Southern one
• Speed varies throughout the tidal cycle
• 2 maximums and 2 minimums in opposite directions
Tide current is
Reversing (and higher),
when restricted to
channels
General features
TIDAL STREAMS
Current rose
(Current ellipse)
Reversing current

25
Nontidal flow effect
TIDAL STREAMS
Effect on a Current rose
Effect on a Reversing current

26
• Time of Tidal Current vs. Time of Tide (not always the same)
• Relationship Between Speed of Current and Range of Tide
• Variation Across an Estuary (speed profile)
• Variation with Depth (velocity, e.g. slack+subsurface movement)
• Tidal current observations are made with sophisticated electronic
current meters.
In general, effect of…
TIDAL STREAMS

• Mechanical current meters
• Acoustic current meters
• Measuring current based on
electromagnetic induction
27
Current meters
TIDAL STREAMS

• Coverage less extensive than for tides prediction (more unpredictable)
• Information required for calculating any tidal current:
• Predicted times of maximum currents and slack times, for Reference
stations
• Differences and ratios for subordinate stations
• Information for current velocity at any time by using (a) and (b)
• Slack durations.
28
Tidal current prediction
TIDAL STREAMS

• 1 knot = 51,4 cm/s = 1,85 km/h
• As high as 13 kn (6,7 m/s; 24 km/h)
29
Tidal Currents Prediction
TIDAL STREAMS
Tidal
atlas
Tidal
diamond

• Not yet widely used, but has a great potential for the future electricity
generation.
• Energy source used since Middle age and Roman times.
• It’s the only technology that draws on energy of the Moon-Earth system.
• Energy practically inexhaustible (renewable energy resource).
• Tidal power causes losses to the Moon-Earth system, shortening the
solar days (negligible effect, noticed over million of years).
30
Introduction
TIDAL POWER

• TSGs o TECs (Energy Converters) use kinetic energy of tidal currents
to produce work in power turbines.
• It’s used also to draw on energy from the river’s currents (nontidal).
• Conceived in 1970s, during the oil crisis.
• It’s the cheapest and least ecologically damaging of the three ways TPG
• Regarding to wind turbines,
• Similar power when water speed is ca. 1 m/s (2 knots)
• 4 times power approx. when water speed is 2-3 m/s (4-6 knots)
• Non uniformity of technologies; 6 principal types recognized by EMEC.
31
1. Tidal stream generator (TSG)
TIDAL POWER

• Close in concept to traditional windmills,
but underwater.
• The most currently operating type.
• Low head of water above  Restricts
individual capacity to about 25 – 50 MW.
• Installations in Canada, UK, Nor. Ireland, USA, Norway, Australia,
China, India, Greek (reaching up to 5 MW); The most are pilot projects.
• Italy: Strait of Messina (Pilot projects). 25-300 kW.
• e.g. Australia, project for 450 turbines in Clarence strait. 300-400
homes each.
• Some projects also in Rivers (e.g. Thames River; nontidal source).
32
1. TSG – Axial turbines
TIDAL POWER
Bottom mounted
axial turbine

33
1. TSG – Axial turbines
TIDAL POWER
AR-1000,
1 MW @ 2,65 m/s
2011
Evopot, 2008 (Prototype)
Cable tethered turbine
Northern Ireland

• Invented by Georges Darreius in 1923.
• Installation either vertical or horizontal.
34
1. TSG – Crossflow turbines
TIDAL POWER
Gorlov turbine
South Korea
Kobold B
Stretto di Messina
2003

Race Rocks
Columbia
2006
• Use of a duct or shroud to augment the flow
going into the turbine.
• Increased significantly the output power.
• They can operate at slow water flows,
increasing the flow velocity
• Growing technology
35
1. TSG – Flow augmented turbines / Venturi
TIDAL POWER

• Do not have a rotating
component.
• They use aerofoil (hydrofoil,
better)
• Growing technology
(prototypes)
• England, Scotland, Australia,
Canada, as precursors.
36
1. TSG – Oscillating Devices
TIDAL POWER
http://vimeo.com/25533045
BioStream:

• Pembrokeshire in Wales
• River Severn between Wales and England
• Cook Strait in New Zealand
• Kaipara Harbour in New Zealand
• Bay of Fundy in Canada.
• East River in the USA
• Golden Gate in the San Francisco Bay
• Piscataqua River in New Hampshire
• The Race of Alderney and The Swinge in the Channel Islands
• The Sound of Islay, between Islay and Jura in Scotland
• Pentland Firth between Caithness and the Orkney Islands, Scotland
• Humboldt County, California in the United States
• Columbia River, Oregon in the United States
• Colombia (Chocó)
37
1. TSG – Potential sites
TIDAL POWER

• Use a dam-like structure, capturing the energy (by turbines) from water
masses moving in and out of a bay (or river).
• Two flow directions (in and out; high tide current and low tide current).
• It’s the oldest method of tidal power generation (since 1960s).
• Few operating plants.
38
2. Tidal barrage
TIDAL POWER
Estuary of the
Rance River
France
240 MW
1966

• The basin is filled with the incoming high tide current.
• Sluice gates are closed.
• When outside water level is low enough (low tide, head enough), gates
are opened to allow water going out, through the turbines.
39
2. Tidal barrage – Ebb Generation
TIDAL POWER

• The basin is emptied with the low
tide.
• When outside water level is high
enough (high tide, head enough),
gates are opened to allow the water
coming into the basin
40
2. Tidal barrage – Flood Generation
TIDAL POWER

• The basin is filled up (by turbines working in reverse), at a high over
the outside high tide.
• When outside water level is low enough (low tide, head enough),
gates are opened to allow water going out, through the turbines.
• The cost of pumping in is returned with the power generation,
because potential energy is proportional to the square of tidal high
variation.
41
2. Tidal barrage – Pumping
TIDAL POWER

• One is filled at high tide, and the other is emptied at low tide.
• Turbines are placed between the basins.
• Offer advantages over normal schemes:
• Adjustment with high flexibility
• Generation almost continuously
• Disadvantages:
• Very expensive to construct (extra lengh of barrage)
42
2. Tidal barrage – Two basins scheme
TIDAL POWER

• It’s a both flood/ebb power generation, but at large scale.
• No plant exists.
• There’s a project called SWANSEA BAY TIDAL LAGOON (South
Wales), where a high power potential exists, with a tidal range of
approx. 10 m.
43
2. Tidal barrage – Tidal lagoon power
TIDAL POWER

• Recent new technology (since 1997). No plants existing.
• Long dam-like structure perpendicular to the coast.
• In addition, a parallel barrier, to form together a T shape
barrier.
• This structure creates water level differences on opposite
sides, which generate electrical power by means of turbines.
• Properly currents for this arrangement:
Some China, Korea and UK coasts.
44
3. Dinamyc Tidal Power (DTP)
TIDAL POWER
http://www.youtube.com/watch?v=4hT4FUlOYr4
Video:

The biggest tidal power station nowadays, all of they Barrage type, are:
(to have a reference, the biggest plant (hydro-electric) in the world produces 22 500 MW)
There are so many projects to be executed, e.g. The Swansea Bay Tidal
Lagoon, or the Australian project for 450 turbines in Clarence strait. 300-
400 homes each.
45
Biggest tidal power plants in the world
TIDAL POWER

• Energy source completely renewable.
• Tides behavior is more predictable than
wind and solar energies.
• New technologies are bringing down
high costs (economical. &
environmental) and improving
efficiencies.
• Most of tidal producing plants do not
affect marine environmental, specifically
TSG and DTP types.
46
Advantages
TIDAL POWER
• High costs compared with another
renewable (and no renewable)
energies.
• Limited availability of properly sites
(flows, velocities).
• Some Tidal Power Plants, specifically
the barrage type, affect the sea
environmental, by killing fishes and/or
modifying estuaries salinity.
• Lack of concluding and contundent
studies about which are the best
technologies.
Disadvantages

• Interface of the Tidal Power Stations output with National Grids, for
example by associating it with the Wireless power (in study).
• Assessment of the Tidal Power Stations economic interest, in order to
promote and sell new ideas for projects.
• New projects for coasts non or a few explored (e.g. South America).
• New studies for minimize the environmental impact of these
technologies.
• Optimizing existing schemes.
• Optimizing efficiencies by means of fluid dynamics analysis.
47
Improvement Opportunities in the Tidal Power Industry
TIDAL POWER

• http://news.enerjienstitusu.com/2012/12/fossil-fuels-still-king-in-eias-annual-energy-
outlook-2013/
• http://wpage.unina.it/agodemar/eolpower/storia.html
• http://www.bbc.co.uk/news/uk-england-humber-16186209
• http://news.bbc.co.uk/2/hi/uk_news/england/8173570.stm
• http://www.tide-project.eu/index.php5?node_id=Reports-and-
Publications;83&lang_id=1
• http://www.neptunerenewableenergy.com/
• http://en.wikipedia.org
• http://www.solarsystemscope.com/
• http://www.visitmyharbour.com/articles/3180/hourly-tidal-streams-irish-sea-and-
bristol-channel
48
References
TIDAL POWER

• http://pemsea.org/eascongress/international-conference/presentation_t4-1_kim.pdf
• Marine-Renewables-News.com
• http://www.marine-renewables-news.com/about-us
• http://www.energias-renovables-marinas.com/
• http://www.onr.navy.mil/focus/ocean/motion/tides2.htm
• http://www.marine.tmd.go.th/marinemet_html/lect19.html
• http://archive.is/s3U4F
• http://www.oceanenergycouncil.com/index.php/Tidal-Energy/Tidal-Energy.html
• iopscience.iop.org/1748-3190/8/3/036011/article
• http://www.youtube.com/watch?v=4hT4FUlOYr4
• http://www.tablademareas.com
49
References
TIDAL POWER

• http://www.edumedia-sciences.com/es/a520-sol-tierra-luna
• http://asteromia.net/luna/la-luna-orbita.html
• http://archive.is/s3U4F
• http://www.gizmodo.com.au/2011/10/how-tide-predicting-machines-saved-d-day/
• http://tidesandcurrents.noaa.gov/constitu.html
• http://web.vims.edu/physical/research/TCTutorial/tideanalysis.htm
• http://www.ams.org/samplings/feature-column/fcarc-tidesiii3
• http://co-ops.nos.noaa.gov/map/
• http://msi.nga.mil/MSISiteContent/StaticFiles/NAV_PUBS/APN/Chapt-09.pdf
50
References
TIDAL POWER

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