Roger Falconer and Chris Binnie - Sustainable Severn Forum 2017

Tidal Energy Opportunities in the

Bristol Channel and Severn Estuary

Roger Falconer1 and Chris Binnie2

1Hydro-environmental Research Centre, Cardiff University

2Independent Water Consultant

1

2

Key details:

• Completed in 1966

• 24 x 5.5m dia. bulb

turbines & 6 sluices

• Turbine trials ebb-

only (+ pumping)

• Generate 0.54TWh/y

• Energy cost €20/MWh

cheapest in EU

• No baseline studies

prior to construction

La Rance Tidal Barrage Scheme

3

Swansea Bay Lagoon - Current DesignKey details:

• Wall 9.7km long

• Area 11.6km2

• 16 x 7.3m diam bulb

turbines & 8 sluices

• Turbines: two-way +

pumping HW & LW

• Generate 0.54TWh/y

• Potential for large

wakes and eddies

4

Swansea Lagoon - Current Predictions

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EBB

FLD

Turbining

0

LW

HW

Sluicing

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Annapolis Barrage - Sluice Gate Wake

Wake from 2 Sluices and 1 x 20 MW turbine

LEGE ND

Order limits

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Sources Ordnance Survey

This drawing may contain: Ordnance Survey material by permission of Ordnance Survey on behalf of the Controller of Her Majesty's Stationery Office © Crown Copyright 2013. All rights reserved. Reference number 0100031673 OS

Open data / © Natural England / © DEFRA / © DECC / © English Heritage. Contains Ordnance Survey data © Crown copyright and database right 2013 I Aerial Photography

REFER TO DRAWING NUMBER 3513/PL/002.3Plan 3of6





T: 01865 887050

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rth

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STATUS Planning

REV . DESCRIPTION APP. DA TE

DOC REF NO: 2.4.1

No dimensions are to be scaled from this drawing.

All dimensions are to be checked on site.

Area measurements for indicative purposes only.

© LDA Design Consulting LLP. Quality Assured to BS EN ISO 9001 : 2008

PR OJ EC T TI TLE

TIDAL LAGOON SWANSEA BAY PROJECT

D R A W I N G T I T L E

Masterplan Key Plan

DATE 06.02.2014 DRAWN JH

CHECKED LJ

APPROVED AK

ISSUED BY Oxford

DWG. NO 3513_PL_001

10.5

9.5

5.2

1.0

0.0

5.5

4.5

0.2

Highest Astronomical Tide (HAT)

Mean High Water Springs (MHWS)

Mean Sea Level (MSL)

-4.0 Mean Low Water Springs (MLWS)

-5.0 Lowest Astronomical Tide (LAT)

10.0

9.0

N/A

1.5

5.0

4.0

N/A

-3.5

Highest Astronomical Tide (HAT)

Mean High Water Springs (MHWS)

Mean Sea Level (MSL)

Mean Low Water Springs (MLWS)

Tidal bar - Outside of the lagoon (NTS)

0.5 -4.5 Lowest Astronomical Tide (LAT)

Tidal bar - Inside of the lagoon (NTS)

Chart

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(m)

Ordnance

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Chart

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Turbine location: Option B


Turbine location: Option A (refer to inset for option B)

Swansea Bay - Design Modification 1

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Revert turbine/sluice location to Option B - submitted to DCO

Wake would be parallel to, and away from, dredged channel

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Focusing turbines and sluice gates leads to high wake/jet effects

Flow through turbines emptying 2 Olympic swimming pools/sec

https://www.ice.org.uk/ICEDevelopmentWebPortal/media/.../6-Ioan-Jenkins.pdf

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Wider distribution of turbines & sluices leads to weaker eddies

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Original Modified


General Findings:

Larger impoundment

size greater impact

Multiple schemes in

close proximity have

cumulative impacts

Impacts reduced by

refined turbine/sluice

design

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Cumulative Impacts Studied

Velocities Elevations

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Velocities Elevations

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Tidal Lagoon - Barrage Interactions

Various Barrage lines (STPG & Atkins) and Lagoons (Cardiff

& Swansea) considered, with interactions studied:

Note: Figures do not include effects of pumping

Results show Barrage would reduce Cardiff output 60% and Cardiff would reduce Barrage output 13%

Run Barrage/Lagoon Annual Energy*

Alone (TWh/yr)

Annual Energy*Combined

1 Severn (HRC) 19.82 17.184

2 Severn (Atkins) 19.77 17.141 (est)

3 Cardiff Lagoon 4.680 1.783

4 Swansea Lagoon 0.586 0.531

Sustainable Severn Forum27th April 2017

Energy opportunity for the estuary

Updating the Severn barrage

By

Prof Chris BinnieMA, DIC, HonDEng, FREng, FICE, FCIWEM

[email protected]

DECC Severn tidal schemes

DECC ebb only generation.

Level of water inside impoundment

Option 1: Generate over ebb tide only

Conclusions of the DECC studyfrom the Executive Summary

• Half of the schemes, including the Cardiff lagoon, were judged to be unviable and were not included in the more detailed consideration.

• The Welsh Grounds lagoon, (Newport lagoon), is no longer considered feasible.

• The Cardiff-Weston, Severn, barrage, 15.6 TWh/y, offers the best value for money.

• Combinations of smaller schemes do not offer cost or energy yield advantages over a single larger scheme between Cardiff and Weston.

Reasons the Severn barrage was not supported.

• Enormous loss of inter-tidal habitat, 118-163 km2

• Birds. Reduction in SPA feeding ground, significant negative effect on 30 species

• Land Drainage. area affected 372km2

• Fish mortality, SAC, possible local extinction of shad and salmon.

• Navigation, • delays to ships transiting the barrage

• BPC planned Deep Sea Container Terminal

Improvements to turbines and operationachieved by TLP, Andritz and GE.

• Ebb/flood generation• Improved basin water levels and generation output

• Pumping• Basin water levels become near normal

• Triple Regulation• Improvement in energy generation

• Non-synchronous generators• Reduced fish mortality

• Smoother passageway• Reduced shear so greatly improved shad mortality

Severn Barrage on the Atkins line

Tidal curve with ebb/flood generation with pumping.

Statistics of the revised barrage

• Energy increased from 15.6 TWh/y to 20.5 TWh/y

• Low water at the barrage increased from 0.34m CD to 0.39m CD, an increase of 0.05m.

• High water at the barrage reduced from 13.84m CD to 13.40m CD, a reduction of 0.44m.

• Mean water level marginally reduced.

Revised impact

• Loss of SAC inter-tidal habitat considerably reduced.

• Loss of bird feeding ground considerably reduced.

• Drainage issue eliminated.

• Fish impact considerably reduced.

• Navigation. Two new container terminals at Liverpool and London Gateway. BPC DSCT postponed.

Comparison of Cardiff and Updated Severn barrage

• Cardiff and Newport lagoons about 8 TWh/y

• Severn barrage about 20 TWh/y.

• Loss of national energy source of about 10 TWh/y

• Severn barrage impact much reduced but still more navigation and fish impact than lagoons.

• Before proceeding, independently update the comparison?

• Welcome Hendry Review and support for Swansea Bay Lagoon as “Pathfinder Project”.

• Swansea Lagoon needs to be successful and would suggest further consideration of two design aspects.

• DECC 2010 Severn Barrage had high impact.

• Tidal energy parameters now much improved.

• Lagoon and barrage impact much reduced.

• Need for independent updated comparison?

Concluding Remarks

Roger Falconer and Chris Binnie - Sustainable Severn Forum 2017

Environment

Transcript of Roger Falconer and Chris Binnie - Sustainable Severn Forum 2017