Marine Energy

1
Institute of PhysicsBristol22 November 2006
Marine Energy
David Kerr Chairman, Energy Board, Institution of
Civil Engineers Engineering Consultant, Sir
Robert McAlpine
2
Marine Energy - Wave Tidal Power

• Tidal Power Barrage
• Use of a Barrage to Impound the Tide extraction
  of the Potential Energy to drive Turbines
  (similar to Hydropower)
• Marine Current (Tidal Stream)
• Extraction of the Kinetic Energy in Tidal
  Currents
• Wave Power
• Extraction of Energy from Wave motion

3
Tidal Barrage PowerProven Technology La Rance
in France has generated tidal power reliably for
nearly 40 years
4
Tidal Power Barrage Operation
5
Ebb Generation (preferred) Flood
Generation Two-way Generation
Tidal Power Barrage Operation - Options
6
Tidal Barrage Power Stations Proposals
7
Severn Tidal Power Barrage Lines considered in
EP46 (1981) Line 5 (inner barrage) selected for
further study
8

• Severn Tidal Barrage
• (inner barrage line)
• Severn Tidal Power Group Report - 1989
• Cardiff (Lavernock point)
• to
• Weston-super-Mare
• 16 km length

9
Facts and Figures (inner barrage)

• Annual Output 17 TWh (5 of UK consumption)
• Installed Capacity 8640 MW
• Renewables Obligation
• 15 by 2015 (50-55TWh) - Barrage cannot
  contribute
• 20 by 2020 would require a further 17TWh.
  Barrage could contribute all of this - if
  sanctioned soon
• Capital Cost 8Bn 1989 gt 14Bn 2005 needs
  re-estimate
• 6 to 7 p/kWh (2005)
• Security of supply benefit
• Constraints
• Uncertain long term electricity market
• Environmental issues

10
Energy Generation (Spring Tide) (Inner barrage)
11
Energy Generation (Neap Tide) (Inner barrage)
12
Flexibility of Output (Inner barrage)
13
Severn Barrage Layout (STPG - 1989 Report)

• 216 Turbines -
  40MW each 8.6GW total
• 166 Sluices 35,000m2
• Ship Locks
• Small Locks
• Public Road
• Railway (possibly)

14
Tidal Power Barrage - Typical cross section The
Barrage impounds the tide, then the water is
released through a bulb turbine to generate
electricity

15
Severn Barrage Construction Caissons built at
deep water sites around the UK ( Europe) and
towed to the site Turbine Generators installed
at the site with heavy lift crane
16
Construction Sequence (EP 57 - 1989 inner
barrage)
17

• Environmental Studies 1989
• (EP 57 - inner barrage)
• A total of 70 studies, with a budget of 2M,
  covering
• Hydrodynamics (tides, currents, waves)
• Sediments, Salinity, Water Quality, Drainage
• Ecology, Birds, Fish
• These studies need updating

18
Severn Tidal Barrage Environmental balance?

• Loss of a unique harsh environment
• Numbers of some bird species may reduce
• Reduction of suspended sediment
• Increased sunlight penetration
• Possible increase in marine life and bird
  species
• Flood protection to Severn Estuary and to
  Rivers
• Carbon Saving

19
Mersey Barrage Proposal 1992 700MW capacity
1.45TWh/year output
20
Siwha Power Barrage Proposal 2005 West coast of
Korea Flood generation scheme to keep basin
water levels low to alleviate pollution in the
lake
21
Siwha Barrage 254MW capacity - output
0.55TWh/yr Construction started 2006
22
Tidal Stream Resource (Black Veitch - for
Carbon Trust - 2004-5)
23
Tidal Stream Sites around the UK

• Tidal Streams around the UK with Spring Tide gt 2
  m/s
• Constraints
• Technology at an early stage
• Best sites are remote
• Costs uncertain at present
• gt9p/KWh for first farms

24
2004
UK Tidal Currents at Mean Spring Tide From Atlas
of Marine Renewable Energy Resources Dti 2004
25
Tidal Current Device Types

• Horizontal axis Turbines
• Vertical axis Turbines
• Oscillating Hydrofoil Devices
• Venturi Devices

26
Tidal Stream Prototypes
Stingray 150kW at 2m/s The Engineering Business
installed 2002 in Shetland Isles

• Seaflow 300kW at 2.7m/s
• Marine Current Turbines - installed 2003 in
  Bristol Channel

27
Tidal Stream Development

• Seagen 1MW device
• Marine Current Turbines
• Proposal -
• Approved 2006 for
• installation in
• Strangford Lough
• Northern Ireland

28
Lunar Energy seated on the seabed 1MW
Prototype planned for 2007
TidEL by Hydrovision- Buoyant device, moored at
mid water depth
29
World Wave Energy Resource kW/m of wave front
(average)
30
UK Annual Mean Wave Power - kW/m From Atlas of
Marine Renewable Energy Resources Dti 2004
31
Wave Power development in the UK

• Very large UK resource 50TWh/yr recoverable
• UK Government funded studies in 1970s-1980s
• Devices were developed Tank tested.
• Several devices appeared promising but estimated
  costs were considered too high. Government
  funding ceased.
• New Government funding for Prototypes since 2000
• Constraints
• How to withstand extreme seas
• Resource remote from demand
• Costs still appear very high gt12p/KWh for first
  farms but should reduce

32
Types of Wavepower Device

• Location
• Shoreline
• Nearshore (seabed mounted)
• Offshore (floating)
• Method of Energy Conversion
• Oscillating Water Column (OWC) - Power extracted
  by Air Turbine. Most prototypes to date are of
  this type.
• Buoyant Moored, on or below surface - Power
  extraction method varies (e.g. from motion of the
  device relative to the seabed)
• Hinged Contour devices - Power extracted at the
  Joints

33
Prototype Wavepower Devices - OWC
Limpet OWC Islay - 2000 Wavegen
34
Prototype Device Hinged Contour type
Pelamis the most promising device to
date Installed at EMEC test site, Orkney in
2004. First commercial order received from
Portugal 2005 750kW device 140m long, 3.5m dia.
35
Prototype installed USA 2006
50kW prototype for Hawaii in 2003
OPT Powerbuoy
36
Summary of Constraints to Development of Marine
Renewables

• For Tidal Barrages
• Environmental Consents
• Financing lack of long term market
• For Tidal Stream Wave
• The need for successful demonstration projects
• Need to reduce costs (especially for Wave Energy)
• Costs of grid connection
• Need for additional support (ROCs ) after
  Demonstration projects and during Development
  stage

37
(No Transcript)
38
Bondi study (EP46 - 1981) was the first major
studyTripartite study (EP57 - 1989) defined the
present schemeCould produce power by 2017 if
progressed soon
Tidal Power from the Severn
39
Sediment Types (figure taken from Bondi)
Rock Gravel Sandy Area -5m OD Contour
Line Muddy Area
40
Flow Patterns with Barrage (inner barrage)
41
Birds - Intertidal sites supporting Waders
Shelduck, Winter 1987-88 (Fig 3.13, EP57)
42

• Caisson Construction Sites
• 1989 report identified potential UK sites shown
• Potential Sites in Europe
• Project and Employment Benefits of using many
  Sites

43
Areas at Risk from Flooding
44
Flood protection in the Severn Estuary and Rivers

• Flooding in the estuary can occur when extreme
  high tides coincide with storm surges
• Flooding in the rivers can occur when these
  same sea conditions coincide also with high river
  flows
• The water level in the basin can be controlled
  -
• To prevent the flooding in the estuary (upstream
  of the barrage)
• To avoid obstruction to river flow caused by
  high tides

45
Water Levels with without Inner Barrage (from
EP 57 - 1989 study)
46
AWS 1MW Prototype installed off Portugal in 2004