Tides and Tidal Energy

JUDITH WOLF

MARINE SYSTEMS MODELLING GROUP, NOC

Outline

• Tidal science at Liverpool

• Modelling the tide

• Some tidal energy studies

• Tidal energy atlas

• Joule project – NW tidal barrages (2006-2008)

• Mersey Tidal Power Feasibility Study (2011)

• Development of Scottish Shelf Waters Model for Marine Scotland (2013-2015)

• Ecowatt2050 project (funded by EPSRC, 2014-2017)

• FLOWBEC – X-band radar measurement of tidal currents

• NERC MREKEP

• CORER (Centre for Offshore Renewable Energy Research) established 2014

Tidal science at Liverpool

Liverpool Tidal Institute established 1919 led by Prof Joseph Proudman

https://www.ntslf.org/ National Tidal and Sea Level Facility

AnyTide iPhone and Android App:

http://noc.ac.uk/using-science/products/anytide-app

Tidal Energy Atlas:

http://www.renewables-atlas.info/

based on NOC POLCOMS HRCS model

Wakelin et al.

(2009)

POLCOMS

Atlantic Margin

Model (AMM)

NOC Liverpool

has been

involved in

development of

digital tidal

models

2-D (depth-

averaged), now

3-D since

1970’s e.g.

Flather (1981);

Recently

unstructured

grids e.g.

ADCIRC (2D),

FVCOM (3D

2-D Modelling using ADCIRC unstructured grid model

(Liverpool University, NOC: Joule Project)

Burrows et al. (2009), Walkington and Burrows (2009)

Grid resolution varies from 15km at the ocean boundary to ~50m in estuaries of

interest: Severn, Dee, Mersey, Ribble, Morecambe Bay and Solway Firth 6

Tidal Power Potential of the Eastern Irish Sea Joule Project results (2009): Tidal barrages in the estuaries of the

North West could meet half the region’s present electricity needs. Low water High water

Barrage

Wolf et al 2009

Wolf et al., 2009)

Scottish Shelf Waters Model

Aims and objectives:

• to develop a validated three dimensional baroclinic hydrodynamic model for Scottish shelf waters, for tides and residual circulation;

• to develop a validated three dimensional hydrodynamic model for each of four identified case study areas (Pentland Firth/Orkney Waters, St Magnus Bay, East Coast of Lewis and Harris, Wider Loch Linnhe System

• to develop a validated wave model for the Pentland Firth and Orkney Waters case study area

• to integrate the case study sub‐models into the wider domain shelf model.

The output of the modelling will provide a quantitative description of marine currents and water properties for the whole of Scottish shelf waters on a range of spatial scales, to inform Marine Scotland and aid in marine management and licensing for MRE and aquaculture.

Scottish Shelf Waters (SSW) FVCOM model

extent

Tidal boundary

TPXO7.2

global tidal

inversion from

TOPEX/Poseidon

altimeter data

(Oregon State

University, Egbert

and Erofeeva,

2002).

Snapshot of depth-averaged current vectors, shading

corresponds to water depth, length of vectors (shown

by black bar) corresponds to current speed (0-2.614 ms-

1)

3-14

Tidal currents in the

Pentland Firth from

SSW model

NOC-L HRCS model M2 cotidal chart

3-13

M2 tide from

POLCOMS

HRCS (high

resolution

continental

shelf) model

Tidal Validation

0.5

0.50.

5

0.5

1

1

1

1

1

1

1

1

1

1

1

1.5

1.5

1.51.52

2

22

2

22

2.5

2.5

2.5

3 3

3

4

-10 -5 0 5 1048

50

52

54

56

58

60

All tidal analysis points (N of 54 deg N)

3-15

Tidal Observations

in Scottish Waters

from BODC)

BODC (British

Oceanographic

Data Centre) is

based at NOC

in Liverpool:

www.bodc.ac.uk

Scatter plots of selected M2 amplitude and phase: left –

elevations, right - currents

3-17

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.5 1 1.5 2

M2 elevation amplitude

0

60

120

180

240

300

360

0 60 120 180 240 300 360

M2 elevation phase

0

20

40

60

80

100

120

0 20 40 60 80 100 120

M2 semi-major amp

0

30

60

90

120

150

180

0 30 60 90 120 150 180

M2 semi-major phase

M2 tidal elevation, % error in amplitude

3-21

M2 tidal elevation, absolute phase error

3-22

M2 tidal ellipses, W Scotland

3-20

Comparison of observed and modelled tidal current ellipses

Tidal Stream Annual Power Density (kW/m2)

18

Development of coupled models

3D Baroclinic Hydrodynamics

Pelagic Model

Benthic Model

Wind Stress - WRF

Irradiation

Cloud Cover

Bo

un

dary

Co

nd

itio

ns

C,N, P,Si

Detritus

Meio-

benthos

Anaerobic

Bacteria

Aerobic

Bacteria

Deposit

Feeders

Phyto-

plankton

Nut

rien

ts

Pelagic Suspension

Feeders

D

e

t

r

i

t

u

s

N

u

t

r

I

e

n

t

s

Oxygenated

Layer

Reduced

Layer

Redox

Discontinuity

Layer

Phytoplankton

Zooplankton

Pico- Flagellates Diatoms

Dissolved

Particulates

Bacteri

a

Micro- Meso- Hetero-

trophs

Small Cells Large Cells

Si

NH4

NO3

PO4

CO2

O

r

g

a

n

i

c

s

N

u

t

r

i

e

n

t

s

Sed S,T,SPM,

K,u,v,w

River

Inputs

Wave Model

Heat Flux

Sustainable use of natural resources

How will barrages, turbines, wind farms and other energy extraction devices affect the flow, hence the sediment transport and ecology?

There may be long term, large area changes in sediment distribution due to changes in tidal flow and waves.

North Hoyle

19

Environmental Impacts

Tides

• Change in tidal regime

• Changes in tidal resource for conjunctive operation of large arrays

• Environmental modification • Intertidal area

• Turbulence and Mixing

• Sediment transport, water quality, morphology

Structures may provide habitats and enhance biodiversity

EcoWatt 2050 (EPSRC): 2014-2017

Led by Prof Jon Side, Heriot-Watt, Orkney

• We will use the Marine Scotland SSW FVCOM model – the validated

model has been delivered to MSS and will be provided to the project

• Coupled 3D hydrodynamic/wave/ecosystem model to be provided by

NOC

• Implement large-scale tidal stream arrays, using the TeraWatt

methodology and run for present day and future climate

European Marine Energy Centre (EMEC) tidal site –

FLOWBEC study site (Orkney, Falls of Warness)

Flood and Ebb Currents at EMEC tidal site using X-band

radar (Paul Bell, NOC Liverpool)

NERC MRE KE programme (hosted at NOC

April 2011-March 2015, led by Paul Bell)

Strategic Objectives: To ensure NERC funded research outcomes generate beneficial impact for the economy, environment and society

• Enhancing and protecting the environment

• Maintaining and enhancing health and wellbeing

• Increasing income, savings, efficiencies, resilience and reducing risk

• Ensuring a strong conduit from research outputs to industry, policy and societal needs http://noc.ac.uk/science-technology/marine-resources/energy/marine-renewables/knowledge-exchange-programme

24

CORER – Centre for Offshore Renewable Energy

Research (NOC, Universities of Southampton and

Liverpool, Ocean University of China, Qingdao

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www.corer.org