Oceanic Energy

1
Oceanic Energy

• Professor S.R. Lawrence
• Leeds School of Business
• University of Colorado
• Boulder, CO 80305

2
Course Outline

• Renewable
• Hydro Power
• Wind Energy
• Oceanic Energy
• Solar Power
• Geothermal
• Biomass

• Sustainable
• Hydrogen Fuel Cells
• Nuclear
• Fossil Fuel Innovation
• Exotic Technologies
• Integration
• Distributed Generation

3
Oceanic Energy Outline

• Overview
• Tidal Power
• Technologies
• Environmental Impacts
• Economics
• Future Promise

• Wave Energy
• Technologies
• Environmental Impacts
• Economics
• Future Promise
• Assessment

4
Overview of Oceanic Energy
5
Sources of New Energy
Boyle, Renewable Energy, Oxford University Press
(2004)
6
Global Primary Energy Sources 2002
Boyle, Renewable Energy, Oxford University Press
(2004)
7
Renewable Energy Use 2001
Boyle, Renewable Energy, Oxford University Press
(2004)
8
Tidal Power
9
Tidal Motions
Boyle, Renewable Energy, Oxford University Press
(2004)
10
Tidal Forces
Boyle, Renewable Energy, Oxford University Press
(2004)
11
Natural Tidal Bottlenecks
Boyle, Renewable Energy, Oxford University Press
(2004)
12
Tidal Energy Technologies

• 1. Tidal Turbine Farms
• 2. Tidal Barrages (dams)

13
1. Tidal Turbine Farms
14
Tidal Turbines (MCT Seagen)

• 750 kW 1.5 MW
• 15 20 m rotors
• 3 m monopile
• 10 20 RPM
• Deployed in multi-unit farms or arrays
• Like a wind farm, but
• Water 800x denser than air
• Smaller rotors
• More closely spaced

MCT Seagen Pile
http//www.marineturbines.com/technical.htm
15
Tidal Turbines (Swanturbines)

• Direct drive to generator
• No gearboxes
• Gravity base
• Versus a bored foundation
• Fixed pitch turbine blades
• Improved reliability
• But trades off efficiency

http//www.darvill.clara.net/altenerg/tidal.htm
16
Deeper Water Current Turbine
Boyle, Renewable Energy, Oxford University Press
(2004)
17
Oscillating Tidal Turbine

• Oscillates up and down
• 150 kW prototype operational (2003)
• Plans for 3 5 MW prototypes

http//www.engb.com
Boyle, Renewable Energy, Oxford University Press
(2004)
18
Polo Tidal Turbine

• Vertical turbine blades
• Rotates under a tethered ring
• 50 m in diameter
• 20 m deep
• 600 tonnes
• Max power 12 MW

Boyle, Renewable Energy, Oxford University Press
(2004)
19
Power from Land Tides (!)
http//www.geocities.com/newideasfromtelewise/tida
lpowerplant.htm
20
Advantages of Tidal Turbines

• Low Visual Impact
• Mainly, if not totally submerged.
• Low Noise Pollution
• Sound levels transmitted are very low
• High Predictability
• Tides predicted years in advance, unlike wind
• High Power Density
• Much smaller turbines than wind turbines for the
  same power

http//ee4.swan.ac.uk/egormeja/index.htm
21
Disadvantages of Tidal Turbines

• High maintenance costs
• High power distribution costs
• Somewhat limited upside capacity
• Intermittent power generation

22
2. Tidal Barrage Schemes
23
Definitions

• Barrage
• An artificial dam to increase the depth of water
  for use in irrigation or navigation, or in this
  case, generating electricity.
• Flood
• The rise of the tide toward land (rising tide)
• Ebb
• The return of the tide to the sea (falling tide)

24
Potential Tidal Barrage Sites
Only about 20 sites in the world have been
identified as possible tidal barrage stations
Boyle, Renewable Energy, Oxford University Press
(2004)
25
Schematic of Tidal Barrage
Boyle, Renewable Energy, Oxford University Press
(2004)
26
Cross Section of a Tidal Barrage
http//europa.eu.int/comm/energy_transport/atlas/h
tmlu/tidal.html
27
Tidal Barrage Bulb Turbine
Boyle, Renewable Energy, Oxford University Press
(2004)
28
Tidal Barrage Rim Generator
Boyle, Renewable Energy, Oxford University Press
(2004)
29
Tidal Barrage Tubular Turbine
Boyle, Renewable Energy, Oxford University Press
(2004)
30
La Rance Tidal Power Barrage

• Rance River estuary, Brittany (France)
• Largest in world
• Completed in 1966
• 2410 MW bulb turbines (240 MW)
• 5.4 meter diameter
• Capacity factor of 40
• Maximum annual energy 2.1 TWh
• Realized annual energy 840 GWh
• Electric cost 3.7/kWh

Tester et al., Sustainable Energy, MIT Press, 2005
Boyle, Renewable Energy, Oxford University Press
(2004)
31
La Rance Tidal Power Barrage
http//www.stacey.peak-media.co.uk/Brittany2003/Ra
nce/Rance.htm
32
La Rance River, Saint Malo
33
La Rance Barrage Schematic
Boyle, Renewable Energy, Oxford University Press
(2004)
34
Cross Section of La Rance Barrage
http//www.calpoly.edu/cm/studpage/nsmallco/clapp
er.htm
35
La Rance Turbine Exhibit
36
Tidal Barrage Energy Calculations

• R range (height) of tide (in m)
• A area of tidal pool (in km2)
• m mass of water
• g 9.81 m/s2 gravitational constant
• 1025 kg/m3 density of seawater
• ? 0.33 capacity factor (20-35)

kWh per tidal cycle
Assuming 706 tidal cycles per year (12 hrs 24 min
per cycle)
Tester et al., Sustainable Energy, MIT Press, 2005
37
La Rance Barrage Example

• 33
• R 8.5 m
• A 22 km2

GWh/yr
Tester et al., Sustainable Energy, MIT Press, 2005
38
Proposed Severn Barrage (1989)
Never constructed, but instructive
Boyle, Renewable Energy, Oxford University Press
(2004)
39
Proposed Severn Barrage (1989)

• Severn River estuary
• Border between Wales and England
• 216 40 MW turbine generators (9.0m dia)
• 8,640 MW total capacity
• 17 TWh average energy output
• Ebb generation with flow pumping
• 16 km (9.6 mi) total barrage length
• 8.2 (15) billion estimated cost (1988)

40
Severn BarrageLayout
Boyle, Renewable Energy, Oxford University Press
(2004)
41
Severn Barrage ProposalEffect on Tide Levels
Boyle, Renewable Energy, Oxford University Press
(2004)
42
Severn Barrage ProposalPower Generation over Time
Boyle, Renewable Energy, Oxford University Press
(2004)
43
Severn Barrage ProposalCapital Costs
Boyle, Renewable Energy, Oxford University Press
(2004)
Tester et al., Sustainable Energy, MIT Press, 2005
44
Severn Barrage ProposalEnergy Costs
Boyle, Renewable Energy, Oxford University Press
(2004)
45
Severn Barrage ProposalCapital Costs versus
Energy Costs
1p ? 2
Boyle, Renewable Energy, Oxford University Press
(2004)
46
Offshore Tidal Lagoon
Boyle, Renewable Energy, Oxford University Press
(2004)
47
Tidal Fence

• Array of vertical axis tidal turbines
• No effect on tide levels
• Less environmental impact than a barrage
• 1000 MW peak (600 MW average) fences soon

Boyle, Renewable Energy, Oxford University Press
(2004)
48
Promising Tidal Energy Sites
http//europa.eu.int/comm/energy_transport/atlas/h
tmlu/tidalsites.html
49
Tidal Barrage Environmental Factors

• Changes in estuary ecosystems
• Less variation in tidal range
• Fewer mud flats
• Less turbidity clearer water
• More light, more life
• Accumulation of silt
• Concentration of pollution in silt
• Visual clutter

50
Advantages of Tidal Barrages

• High predictability
• Tides predicted years in advance, unlike wind
• Similar to low-head dams
• Known technology
• Protection against floods
• Benefits for transportation (bridge)
• Some environmental benefits

http//ee4.swan.ac.uk/egormeja/index.htm
51
Disadvantages of Tidal Turbines

• High capital costs
• Few attractive tidal power sites worldwide
• Intermittent power generation
• Silt accumulation behind barrage
• Accumulation of pollutants in mud
• Changes to estuary ecosystem

52
Wave Energy
53
Wave Structure
Boyle, Renewable Energy, Oxford University Press
(2004)
54
Wave Frequency and Amplitude
Boyle, Renewable Energy, Oxford University Press
(2004)
55
Wave Patterns over Time
Boyle, Renewable Energy, Oxford University Press
(2004)
56
Wave Power Calculations
Hs2 Significant wave height 4x rms water
elevation (m) Te avg time between upward
movements across mean (s) P Power in kW per
meter of wave crest length
Example Hs2 3m and Te 10s
57
Global Wave Energy Averages
Average wave energy (est.) in kW/m (kW per meter
of wave length)
http//www.wavedragon.net/technology/wave-energy.h
tm
58
Wave Energy Potential

• Potential of 1,500 7,500 TWh/year
• 10 and 50 of the worlds yearly electricity
  demand
• IEA (International Energy Agency)
• 200,000 MW installed wave and tidal energy power
  forecast by 2050
• Power production of 6 TWh/y
• Load factor of 0.35
• DTI and Carbon Trust (UK)
• Independent of the different estimates the
  potential for a pollution free energy generation
  is enormous.

http//www.wavedragon.net/technology/wave-energy.h
tm
59
Wave Energy Technologies
60
Wave Concentration Effects
Boyle, Renewable Energy, Oxford University Press
(2004)
61
Tapered Channel (Tapchan)
http//www.eia.doe.gov/kids/energyfacts/sources/re
newable/ocean.html
62
Oscillating Water Column
http//www.oceansatlas.com/unatlas/uses/EnergyReso
urces/Background/Wave/W2.html
63
Oscillating Column Cross-Section
Boyle, Renewable Energy, Oxford University Press
(2004)
64
LIMPET Oscillating Water Column

• Completed 2000
• Scottish Isles
• Two counter-rotating Wells turbines
• Two generators
• 500 kW max power

Boyle, Renewable Energy, Oxford University Press
(2004)
65
Mighty Whale Design Japan
http//www.jamstec.go.jp/jamstec/MTD/Whale/
66
Might Whale Design
Boyle, Renewable Energy, Oxford University Press
(2004)
67
Turbines for Wave Energy
Turbine used in Mighty Whale
Boyle, Renewable Energy, Oxford University Press
(2004)
http//www.jamstec.go.jp/jamstec/MTD/Whale/
68
Ocean Wave Conversion System
http//www.sara.com/energy/WEC.html
69
Wave Conversion System in Action
70
Wave Dragon
Wave Dragon Copenhagen, Denmark http//www.WaveDra
gon.net
Click Picture for Video
http//www.wavedragon.net/technology/wave-energy.h
tm
71
Wave Dragon Energy Output

• in a 24kW/m wave climate 12 GWh/year
• in a 36kW/m wave climate 20 GWh/year
• in a 48kW/m wave climate 35 GWh/year
• in a 60kW/m wave climate 43 GWh/year
• in a 72kW/m wave climate 52 GWh/year.

http//www.wavedragon.net/technology/wave-energy.h
tm
72
Declining Wave Energy Costs
Boyle, Renewable Energy, Oxford University Press
(2004)
73
Wave Energy Power Distribution
Boyle, Renewable Energy, Oxford University Press
(2004)
74
Wave Energy Supply vs. Electric Demand
Boyle, Renewable Energy, Oxford University Press
(2004)
75
Wave Energy Environmental Impacts
76
Wave Energy Environmental Impact

• Little chemical pollution
• Little visual impact
• Some hazard to shipping
• No problem for migrating fish, marine life
• Extract small fraction of overall wave energy
• Little impact on coastlines
• Release little CO2, SO2, and NOx
• 11g, 0.03g, and 0.05g / kWh respectively

Boyle, Renewable Energy, Oxford University Press
(2004)
77
Wave Energy Summary
78
Wave Power Advantages

• Onshore wave energy systems can be incorporated
  into harbor walls and coastal protection
• Reduce/share system costs
• Providing dual use
• Create calm sea space behind wave energy systems
• Development of mariculture
• Other commercial and recreational uses
• Long-term operational life time of plant
• Non-polluting and inexhaustible supply of energy

http//www.oceansatlas.com/unatlas/uses/EnergyReso
urces/Background/Wave/W2.html
79
Wave Power Disadvantages

• High capital costs for initial construction
• High maintenance costs
• Wave energy is an intermittent resource
• Requires favorable wave climate. 
• Investment of power transmission cables to shore
• Degradation of scenic ocean front views
• Interference with other uses of coastal and
  offshore areas
• navigation, fishing, and recreation if not
  properly sited
• Reduced wave heights may affect beach processes
  in the littoral zone

http//www.oceansatlas.com/unatlas/uses/EnergyReso
urces/Background/Wave/W2.html
80
Wave Energy Summary

• Potential as significant power supply (1 TW)
• Intermittence problems mitigated by integration
  with general energy supply system
• Many different alternative designs
• Complimentary to other renewable and conventional
  energy technologies

http//www.oceansatlas.com/unatlas/uses/EnergyReso
urces/Background/Wave/W2.html
81
Future Promise
82
World Oceanic Energy Potentials (GW)

• Source
• Tides
• Waves
• Currents
• OTEC1
• Salinity
• World electric2
• World hydro

• Potential (est)
• 2,500 GW
• 2,7003
• 5,000
• 200,000
• 1,000,000
• 4,000

• Practical (est)
• 20 GW
• 500
• 50
• 40
• NPA4
• 2,800
• 550

1 Temperature gradients 2 As of 1998
3 Along coastlines
4 Not presently available
Tester et al., Sustainable Energy, MIT Press, 2005
83
Solar Power Next Week
http//www.c-a-b.org.uk/projects/tech1.jpg