Tidal PowerTidal Power

CAUSE 2003 Final ProjectCAUSE 2003 Final ProjectPete ClarkPete Clark

Rebecca KlossnerRebecca KlossnerLauren KologeLauren Kologe

OverviewOverview• IntroductionIntroduction• Basic Science of TidesBasic Science of Tides• Historical AspectsHistorical Aspects• New Technology from an Old IdeaNew Technology from an Old Idea• La Rance Case StudyLa Rance Case Study• Severn Project – Will There Ever Be a Barrage?Severn Project – Will There Ever Be a Barrage?• Long Island Sound Barrage Case Study for the Long Island Sound Barrage Case Study for the

FutureFuture• Fundy Bay - Case StudyFundy Bay - Case Study

– Environmental Impacts of Tidal EnergyEnvironmental Impacts of Tidal Energy– Economics of Tidal EnergyEconomics of Tidal Energy– Policy ConcernsPolicy Concerns– Other Tidal SchemesOther Tidal Schemes

• A More Futuristic Approach –Artificial Reef A More Futuristic Approach –Artificial Reef Program: Offshore RigsProgram: Offshore Rigs

Basic Science of Basic Science of the Tidesthe Tides

Lunar Tidal DynamicsLunar Tidal Dynamics

Tidal BasicsTidal Basics

• Most locations have two tidal cycles per Most locations have two tidal cycles per day: 12 hours, 25 minutesday: 12 hours, 25 minutes

• Essentially caused by interaction of moon, Essentially caused by interaction of moon, earth, and sun centrifugal forcesearth, and sun centrifugal forces

• Diurnal tides are generated because the Diurnal tides are generated because the maxima and minima in each daily rotation maxima and minima in each daily rotation are unequal in amplitude are unequal in amplitude

Newton’s Law of Newton’s Law of Gravitational State Gravitational State

F = G F = G m1m2m1m2

RR22

Tidal Force = Tidal Force = 2Gmm1a2Gmm1a R R33

Distance between Earth and Moon

Radius of Earth

Particle (Water)

Tidal FactsTidal Facts

• Tidal Range = Distance between high Tidal Range = Distance between high tide mark and low tide marktide mark and low tide mark

• Largest RangesLargest Ranges Coastal Regions with Coastal Regions with extreme depth gradient (Mouzel = extreme depth gradient (Mouzel = excellent tidal range)excellent tidal range)

• Smallest RangesSmallest Ranges Open Ocean (<.5 m) Open Ocean (<.5 m)

Spring TidesSpring Tides

• Year roundYear round

• Occur during full moon and new moonOccur during full moon and new moon

• Due to the linear pattern of SMEDue to the linear pattern of SME

• Causes stronger tides: increased current Causes stronger tides: increased current and tidal rangesand tidal ranges

Neap TidesNeap Tides

• Moon and sun are perpendicular to Moon and sun are perpendicular to each other each other

• Weak currents, lower tidal rangesWeak currents, lower tidal ranges

• Occur during quarter moonsOccur during quarter moons

Neap Tides Versus Spring Neap Tides Versus Spring TidesTides

Bulging

Effect

Barrage LogisticsBarrage Logistics

• Largest surface area, greatest tidal Largest surface area, greatest tidal rangerange– Square EffectSquare Effect

• Effects of ecosystem (fish, sediment, Effects of ecosystem (fish, sediment, etc.)etc.)

• Proximity to populationProximity to population

Waterway Measurement Waterway Measurement LogisticsLogistics

  Mean Tidal Amplitude(m) Basin Area (km2)

La Rance, France 4 17

Bay of Fundy, Canada 5.5 240

Annapolis, Nova Scotia 3.2 6

Severn Estuary 4 420Garolim Bay, South

Korea 2.5 85

Bay of Fundy VS Chesapeake Bay of Fundy VS Chesapeake BayBay

Greater Friction

Historical Historical AspectsAspects

Ancient Tide MillsAncient Tide Mills

• During the Roman occupation of During the Roman occupation of England, tide mills were built to grind England, tide mills were built to grind grain and corngrain and corn

• These tide mills operated by storing These tide mills operated by storing water behind a dam during high tide. water behind a dam during high tide. As the tide receded the water was As the tide receded the water was slowly let out from behind the dam in slowly let out from behind the dam in order to power the mill. order to power the mill.

Nendrum Monastic Tidal Nendrum Monastic Tidal SiteSite• Discovered in 1999Discovered in 1999

• Unveiled was a Unveiled was a stone built tidal stone built tidal mill and evidence mill and evidence of an ancient tidal of an ancient tidal mill dating back to mill dating back to 787 A.D. 787 A.D.

Eling MillEling Mill

• The mill was included in the The mill was included in the Domesday Survey of 1086Domesday Survey of 1086

• Originally milled four tons of flour Originally milled four tons of flour each day at maximum outputeach day at maximum output

• Rebuilt many times, but operates in Rebuilt many times, but operates in the same mannerthe same manner

Eling Mill – How it WorksEling Mill – How it Works

Eling MillEling Mill

Tide Pond Tide Mill

The Sea

New Technology New Technology from an Old Ideafrom an Old Idea

Industrial RevolutionIndustrial Revolution

• Brought cheap energy in the form of Brought cheap energy in the form of electricityelectricity

• Small tidal mills were replaced with Small tidal mills were replaced with large steam-powered roller millslarge steam-powered roller mills

• Paleotechnic period means full steam Paleotechnic period means full steam ahead with little though of what was ahead with little though of what was happening to the environment happening to the environment

From Milling to ElectricityFrom Milling to Electricity• Most common generating system is the Most common generating system is the

ebb generating systemebb generating system

• Double effect turbines are now Double effect turbines are now becoming technologically feasiblebecoming technologically feasible

ConstructionConstruction

• Caissons are manufactured at shore-Caissons are manufactured at shore-based construction yards are delivered based construction yards are delivered to water sites by barges and then to water sites by barges and then positioned by cranes to allow for the positioned by cranes to allow for the structures to correctly settle on the structures to correctly settle on the marine floor. marine floor.

• Another method calls for constructing Another method calls for constructing diaphragm walls of reinforced concrete diaphragm walls of reinforced concrete within a temporary sand island. within a temporary sand island.

LocationLocation

• Tidal mills were usually built on inlets Tidal mills were usually built on inlets branching off tidal estuaries. branching off tidal estuaries.

• An estuary is a wide part of a river where An estuary is a wide part of a river where it meets the sea. it meets the sea.

• Tidal estuaries are characterized by Tidal estuaries are characterized by narrow, shallow channels with a relatively narrow, shallow channels with a relatively constant width and depth.constant width and depth.

• Tides are greatly amplified in these areas Tides are greatly amplified in these areas of smaller volume, which causes the tide of smaller volume, which causes the tide to travel up the river. to travel up the river.

Tidal BarrageTidal Barrage

• Similar to a damSimilar to a dam

• Structure must span the entire width Structure must span the entire width and height of the estuaryand height of the estuary

Evolution of Turbine TypesEvolution of Turbine Types

• Waterwheel Waterwheel turbines were turbines were used in tidal millsused in tidal mills

Overshot

Breast-shot

Undershot

Recent TurbinesRecent Turbines

• Bulb, Rim, and TubularBulb, Rim, and Tubular

Bulb Turbine (Copyright Boyle, 1996)

Rim Turbine (Copyright Boyle, 1996)

Tubular Turbine (Copyright Boyle, 1996)

La Rance Case La Rance Case StudyStudy

La Rance Tidal Power PlantLa Rance Tidal Power Plant

• Only full scale Only full scale power station of its power station of its type in the worldtype in the world

• Located in northern Located in northern France on the La France on the La Rance River Rance River

La RanceLa Rance

• Completed in 1967 after 25 years of Completed in 1967 after 25 years of studies and six years of constructionstudies and six years of construction

• 24 bulb turbines, each capable of 24 bulb turbines, each capable of producing ten megawatts of powerproducing ten megawatts of power

• The dam is 2460 feet (750 meters) The dam is 2460 feet (750 meters) long, and 43 feet (13 meters) highlong, and 43 feet (13 meters) high

• One of the greatest tidal ranges in One of the greatest tidal ranges in the world, at 13.5m. the world, at 13.5m.

La Rance TurbinesLa Rance Turbines

• Bulb turbines Bulb turbines • The blades of the turbine can change The blades of the turbine can change

directions depending on the current flow. directions depending on the current flow. • The turbines weigh 470 tons and have a The turbines weigh 470 tons and have a

blade diameter of over seventeen feet. blade diameter of over seventeen feet. • The plant is also equipped with pumps that The plant is also equipped with pumps that

allow water to be pumped into the basin allow water to be pumped into the basin when the sea is close to basin level at high when the sea is close to basin level at high tide. This allows for more electricity to be tide. This allows for more electricity to be generated if there is an anticipated generated if there is an anticipated increase in demand. increase in demand.

No Drawbacks?No Drawbacks?

• No adverse impact on species native to the No adverse impact on species native to the waterwater

• No flooding has occurredNo flooding has occurred

• Road was createdRoad was created

• Tourist siteTourist site

• Generates electricity for over 300,000 Generates electricity for over 300,000 homeshomes

• Not all tidal barrages will have such Not all tidal barrages will have such negligible affectsnegligible affects

Severn Project Severn Project

Severn Barrage HistorySevern Barrage History

• Second largest tidal ranges in the worldSecond largest tidal ranges in the world• Proposals to dam the Severn have Proposals to dam the Severn have

existed for over one hundred yearsexisted for over one hundred years• When the Severn Barrage concept was When the Severn Barrage concept was

originally proposed in the 1840s, it was originally proposed in the 1840s, it was to improve shipping and prevent to improve shipping and prevent flooding. In addition, the barrage would flooding. In addition, the barrage would create a roadway and railway across create a roadway and railway across the river. the river.

Power Plant ProposalsPower Plant Proposals

• Proposal in 1918, but the low cost of coal used to Proposal in 1918, but the low cost of coal used to generate electricity did not make the project generate electricity did not make the project economically feasible.economically feasible.

• In 1943 the formation Brabazon Commission to In 1943 the formation Brabazon Commission to reinvestigate the barrage. reinvestigate the barrage. – The proposal called for a single basin operating on The proposal called for a single basin operating on

discharge only that would produce 800,000 kilowatts of discharge only that would produce 800,000 kilowatts of output (UN, 1957).output (UN, 1957).

– Again, the plan was abandoned, because of poor economic Again, the plan was abandoned, because of poor economic feasibility. feasibility.

• The Severn Barrage Committee was organized in The Severn Barrage Committee was organized in 19781978– The committee spent two and a half years deciding that a The committee spent two and a half years deciding that a

barrage across the Severn would be technologically barrage across the Severn would be technologically feasible, but not economically feasible feasible, but not economically feasible

The Proposed SchemeThe Proposed Scheme• 10 mile long barrage between Brean Down in 10 mile long barrage between Brean Down in

Somerset and Lavernock Point in Glamorgan. Somerset and Lavernock Point in Glamorgan. • The tidal basin would be over 190 square miles The tidal basin would be over 190 square miles

(500 square kilometers). (500 square kilometers). • The proposed barrage would be comprised of The proposed barrage would be comprised of

caissons to house the turbines and sluices. caissons to house the turbines and sluices. • The 216 tubular turbines would be located in the The 216 tubular turbines would be located in the

central portion of the barrage, and each would central portion of the barrage, and each would drive a 40 megawatt generatordrive a 40 megawatt generator

• Estimated 17TWh each year Estimated 17TWh each year • The proposed scheme has a lifetime of at least The proposed scheme has a lifetime of at least

120 years 120 years • Ship locks were also included in the schemeShip locks were also included in the scheme• Ebb generating scheme with pumpsEbb generating scheme with pumps

Will It Be Feasible?Will It Be Feasible?• What has changed?What has changed?

– KyotoKyoto– Government Policy – Renewables Government Policy – Renewables

ObligationObligation– Global Warming and possible flooding?Global Warming and possible flooding?

The Renewables ObligationThe Renewables Obligation

• 10% of electricity from renewables 10% of electricity from renewables by 2010, 20% by 2020by 2010, 20% by 2020

• This scheme could provide 6% of the This scheme could provide 6% of the UK’s total electricityUK’s total electricity

• Not online until at least 2014Not online until at least 2014

Kyoto ProtocolKyoto Protocol

• The Protocol calls for developed The Protocol calls for developed nations to reduce their greenhouse nations to reduce their greenhouse gas emissions. gas emissions.

• A market based permit system was A market based permit system was used to create incentive for used to create incentive for greenhouse gas emission reductions. greenhouse gas emission reductions.

• The electricity from the barrage would The electricity from the barrage would avoid the emission of eighteen million avoid the emission of eighteen million tons of carbon dioxide every year. tons of carbon dioxide every year.

FloodingFlooding

• Global Warming may cause flooding and Global Warming may cause flooding and coastal erosion in the Severn Estuary coastal erosion in the Severn Estuary RegionRegion

• The annual average flooding damage cost The annual average flooding damage cost risk currently totals £40-200 million, and risk currently totals £40-200 million, and this is expected to rise. this is expected to rise.

• These costs and costs of potentially These costs and costs of potentially installing flood mitigation could be avoided installing flood mitigation could be avoided if the Severn Barrage was constructed.if the Severn Barrage was constructed.

New Definition Study – New New Definition Study – New Hope?Hope?

• Costs are still very high (Costs are still very high (£10.3 – 14 £10.3 – 14 billion) and the project could take up billion) and the project could take up to nine years to construct. to nine years to construct.

• Difficult to find investors because of Difficult to find investors because of long payback period.long payback period.

• If positive externalities are included If positive externalities are included in the market, then the electricity in the market, then the electricity from tidal can be competitive with from tidal can be competitive with that of other resourcesthat of other resources

Long Island Sound Long Island Sound Barrage Case Study Barrage Case Study

for the Futurefor the Future

Where on the East Coast do Where on the East Coast do we have a large population we have a large population

near a waterway with a large near a waterway with a large tidal range?tidal range?

Long Island SoundLong Island Sound

Long Island Sound BarrageLong Island Sound Barrage

• Tidal range increases heading westTidal range increases heading west

• Max tidal range = 10 metersMax tidal range = 10 meters

• Build barrage halfway into soundBuild barrage halfway into sound greater range, greater range, less surface arealess surface area

• Surface Area = 2,092 kmSurface Area = 2,092 km22

• Tidal Amplitude = 3.5 meters at Mt. Sinai Tidal Amplitude = 3.5 meters at Mt. Sinai

Placement of Barrage Placement of Barrage StructureStructure

Levy System for traffic

South half of Sound is shallow =less freighter traffic

Theoretical Mean Power Theoretical Mean Power OutputOutput

S ∫ ρgdz S ∫ ρgdz

2SρgH2SρgH22 Surface Area

Gravitational Acceleration

Mean Amplitude of Tide

Surface Area Density

Gravitational Acceleration

Change in Water Height Column

LI Sound Barrage—Energy LI Sound Barrage—Energy OutputOutput

2,135 Mw2,135 Mw

-About 1/3 of what is expected from -About 1/3 of what is expected from Severn BarrageSevern Barrage

-If calculations were 85% inaccurate, -If calculations were 85% inaccurate, LISB would still produce more power LISB would still produce more power

than La Rancethan La Rance

Major Setback—Fishery Major Setback—Fishery MigrationMigration

Would Barrage help clean up Would Barrage help clean up sediment problem?sediment problem?

Fundy Bay - Case StudyFundy Bay - Case Study

Environmental Impacts of Tidal Environmental Impacts of Tidal EnergyEnergy

Economics of Tidal EnergyEconomics of Tidal EnergyPolicy ConcernsPolicy ConcernsOther Tidal SchemesOther Tidal Schemes

Romancing the Romancing the TideTide

Creating a new paradigm for Creating a new paradigm for

renewable energy choices renewable energy choices

Impacts Impacts

• Environmental Environmental

• Economic Economic

• Social Social

Boundary Layer EffectsBoundary Layer Effects

http://129.173.3.163/BBLCh1.html

Red Tide Incidence Red Tide Incidence

Bunnies aren’t ferocious Bunnies aren’t ferocious enoughenough

But Squirrels AreBut Squirrels Are

Politics and Policy: Spin makes Politics and Policy: Spin makes the earth go ‘round the earth go ‘round

City by the bayCity by the bay

San Francisco’s Tidal Power San Francisco’s Tidal Power PotentialPotential

The Loyal Subjects of King The Loyal Subjects of King CanuteCanute

It’s the end of the world It’s the end of the world as we know it …as we know it …• Yesterday is past, the future will come Yesterday is past, the future will come

without warning, but today is a without warning, but today is a presentpresent

• We cannot go back to the historical We cannot go back to the historical context of a sparsely populated world ~ context of a sparsely populated world ~ our energy choices today reflect a our energy choices today reflect a different starting point different starting point

Choose your own futureChoose your own future

http://www.open.ac.uk/T206/4longtour.htm http://www.infinitytrading.com/crude_oil_futures_options.html

A More Futuristic A More Futuristic Approach –Artificial Approach –Artificial

Reef Program: Offshore Reef Program: Offshore RigsRigs

NJ Artificial Reef ProgramNJ Artificial Reef Program

Marine Conservation Marine Conservation StructureStructure

Maximized Conservation

ConclusionsConclusions

• Tidal Energy is interesting!Tidal Energy is interesting!

• Economics are difficult to get aroundEconomics are difficult to get around

• These projects are expensiveThese projects are expensive

• Are people really willing to pay?Are people really willing to pay?