Energy and the New Reality, Volume 2: C-Free Energy Supply Chapter 7: Ocean Energy L. D. Danny Harvey [email protected]This material is intended for use in lectures, presentations and as handouts to students, and is provided in Powerpoint format so as to allow customization for the individual needs of course instructors. Permission of the author and publisher is required for any other usage. Please see www.earthscan.co.uk for contact details. Publisher: Earthscan, UK Homepage: www.earthscan.co.uk/?tabid=101808
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This material is intended for use in lectures, presentations and as handouts to students, and is provided in Powerpoint format so as to allow customization for the individual needs of course instructors. Permission of the author and publisher is required for any other usage. Please see www.earthscan.co.uk for contact details.
Figure 7.1 Wave power density (kW per m of coastline) along the world’s coastline
Source: Boud (2002, Status and Research and Development Priorities 2003, Wave and Marine Current Energy, International Energy Agency, Implementing Agreement on Ocean Energy Systems)
Figure 7.2a A shoreline wave energy conversion device
Source: Khan and Bhuyan (2009, Ocean Energy: Global Technology Development and Status, IEA-OES Document T0104 )
Incoming wave
Motion of water column
Air co lumn
Air flow
Front wall of concrete chamber Turbine and generator
Figure 7.2b A floating wave energy conversion device
TURBINE HOUSING
TURBINE DUCTS
FLOODABLE TANKS
BUOYANCYMATER IAL
MOO NPOOL
AIRFLOW
REMO VABLE UNIT
Source: Khan and Bhuyan (2009, Ocean Energy: Global Technology Development and Status, IEA-OES Document T0104 )
Figure 7.3 Rotation of the Earth and moon around a common centre and the resulting bulge in the ocean surface due to the resulting centrifugal force
m oon e a rth
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
Figure 7.4 The variation in tidal range within the Severn Estuary of the UK
Severn Bridge
Cardiff
Weston-super-Mare10m
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
Figure 7.5a Variation in water level outside and inside a tidal barrage (dam) designed to produce power only during the flood flow
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
sea level
basinlevel
time of day
Figure 7.5b Variation in water level outside and inside a tidal barrage (dam) designed to produce power only during the ebb flow
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
sealevel
time of day
basin level
Figure 7.5c Variation in water level outside and inside a tidal barrage (dam) designed to produce power during both
the flood and ebb flows
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
sea level
time of day
basin level
Figure 7.6a A bulb tidal turbine
Source: Boud (2002, Status and Research and Development Priorities 2003, Wave and Marine Current Energy, International Energy Agency, Implementing Agreement on Ocean Energy Systems)
generator insideturbine runner
distributorsteady plinth
bulb hanger
water flow
bulb casing
Figure 7.6b A stratflo tidal turbine
Source: Boud (2002, Status and Research and Development Priorities 2003, Wave and Marine Current Energy, International Energy Agency, Implementing Agreement on Ocean Energy Systems)
runner
generator
Figure 7.6c A tubular tidal turbine
Source: Boud (2002, Status and Research and Development Priorities 2003, Wave and Marine Current Energy, International Energy Agency, Implementing Agreement on Ocean Energy Systems)
runner
gear box
generator
Figure 7.7 Potential sites for tidal barrages along with the tidal range (m) and potential installed power capacity (GW)
Source: Elliott (1996, Renewable Energy: Power for a Sustainable Future, Oxford University Press, Oxford)
Figure 7.8 Proposed tidal current energy devices
Source: Boud (2002, Status and Research and Development Priorities 2003, Wave and Marine Current Energy, International Energy Agency, Implementing Agreement on Ocean Energy Systems)
Figure 7.9 Proposed tidal-current turbines
Source: www.e-tidevannsenergi.com
Figure 7.10 Vertical variation in temperature in the upper 1.5 km of the ocean at various tropical and subtropical locations
0
200
400
600
800
1000
1200
1400
0 5 10 15 20 25 30 35
Temperature (°C)
Dep
th (
m)
Hawaii
Puerto Rico
The Gulf of Mexico
Naul
Source: www.xenesys.com
Figure 7.11 Geographical variation in the difference in temperature between the ocean surface and ‘deep’ water
(typically at a depth of 1000 m)
Source: www.xenesys.com
Figure 7.12 A closed-cycle OTEC process based on the Rankine cycle
Evaporator
Working Fluid (Vapour)
P
P
Warm SurfaceSeawater
Turbine
Generator
Condenser
Cold DeepSeawater
Working Fluid (Liquid)
PPump
Pump
Pump
Source: Khan and Bhuyan (2009, Ocean Energy: Global Technology Development and Status, IEA-OES Document T0104 )
Figure 7.13 A pressure-retarded osmosis process for generating electricity from a salinity gradient
Source: Khan and Bhuyan (2009, Ocean Energy: Global Technology Development and Status, IEA-OES Document T0104 )