1. Oceanic Energy Professor S.R. Lawrence Leeds School of Business
University of Colorado
Boulder, CO

2. Course Outline Renewable Oceanic Energy Sustainable 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
Marine current turbines work, in principle, much like submerged windmills, but driven by flowing water rather than air. They can be installed in the sea at places with high tidal current velocities, or in a few places with fast enough continuous ocean currents, to take out energy from these huge volumes of flowing water. These flows have the major advantage of being an energy resource which is mostly as predictable as the tides that cause them, unlike wind or wave energy which respond to the more random quirks of the weather system. The technology under development by MCT consists of twin axial flow rotors of 15m to 20m in diameter, each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter which is set into a hole drilled into the seabed.
The submerged turbines, which will generally be rated at from 750 to 1500kW per unit (depending on the local flow pattern and peak velocity), will be grouped in arrays or "farms" under the sea, at places with high currents, in much the same way that wind turbines in a wind farm are set out in rows to catch the wind. The main difference is that marine current turbines of a given power rating are smaller, (because water is 800 times denser than air) and they can be packed closer together (because tidal streams are normally bi-directional whereas wind tends to be multi-directional).
Environmental Impact Analyses completed by independent consultants have confirmed our belief that the technology does not offer any serious threat to fish or marine mammals. The rotors turn slowly (10 to 20 rpm) (a ship's propeller, by comparison, typically runs 10 times as fast and moreover our rotors stay in one place whereas some ships move much faster than sea creatures can swim). The risk of impact from our rotor blades is extremely small bearing in mind that virtually all marine creatures that choose to swim in areas with strong currents have excellent perceptive powers and agility, giving them the ability to successfully avoid collisions with static or slow-moving underwater obstructions.
MCT Seagen Pile

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
The "Swanturbines" design is different to other devices in a number of ways. The most significant is that it is direct drive, where the blades are connected directly to the electrical generator without a gearbox between. This is more efficient and there is no gearbox to go wrong. Another difference is that it uses a "gravity base", a large concrete block to hold it to the seabed, rather than drilling into the seabed. Finally, the blades are fixed pitch, rather than actively controlled, this is again to design out components that could be unreliable.

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
Stingray is designed to extract energy from water that flows due to tidal effects - tidal stream energy. It consists of a hydroplane which has its attack angle relative to the approaching water stream varied by a simple mechanism. This causes the supporting arm to oscillate which in turn forces hydraulic cylinders to extend and retract. This produces high pressure oil which is used to drive a generator.
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 (!)
The tidal activity in land is much smaller than that of in the sea because of its less flexibility and high density. With the help of a hydraulic system, it is possible to extract energy from land tidal activity.  When the tide occur, the top surface of the Earth will move up and down and  the body structure of the mechanism fixed on the top surface will also move up and down (see diagrams below). But there occurs a relative motion between the top surface of the Earth and the bottom of the supporting stand because of the density difference between the top and bottom (density will be less on the top surface), flexibility (elasticity) difference between the top and bottom (flexibility will be more on the top surface). The large two-way head piston is rigidly connected to the strong rigid-supporting stand and which is rigidly fixed in the bottom of the deep well.
During the upward motion of the cylinder (assume that the relative movement between the top and bottom is about 1cm), as the large two- way head piston is remaining stationary related to the bottom, the inside volume of lower chamber will decrease and the fluid in it will experience a high pressure, that causes the fluid in it with a volume of  m3 to escape through the 32.3cm diameter cylinder (Sc4 - see.fig) provided on the body structure. Since there is a small piston 4(Sp4) which can slide through its small cylinder, the fluid will push this piston in 1meter and the one way  piston 2 (Lp2) connected on the other end will also moves 1meter. Since the diameter of the one way cylinder2 (Lc2) is 1meter then, the volume of the displaced fluid by Lp2 will be 0.785m3 and  this fluid will escape through 37.7 cm diameter cylinder 3 (Sc3). This causes, the  small piston 3 (Sp3)  and the small piston 2 (Sp2) with the rack slides through the small cylinder 2(Sc2) and small cylinder 3 (Sc3) in 7meter. As the rack  is meshing with the pinions P1 & P2, it will rotate and through the gear train of the required gear ratio the power will be transferred to the rotor of the generator; and by its rotation, electricity will be produced.
Similarly, during the down ward motion of the cylinder, in the tidal-fall, the inside volume of upper chamber will decrease and the fluid in it will experience a high pressure that causes the fluid in it with a volume of  0.1m3 to escape through the 35.6cm diameter cylinder (Sc1 - see.fig) provided on the body structure. Since there is a small piston 1(Sp1) which can slide through its small cylinder, the fluid will push this piston in 1meter and the one way  piston 1 (Lp1) connected on the other end will also moves 1meter. Since the diameter of the one way cylinder1 (Lc1) is 1meter then, the volume of the displaced fluid by Lp1 will be 0.785m3 and  this fluid will escape through 37.7 cm diameter cylinder 2(Sc2). This causes the small piston 2 (Sp2) and small piston 3 (Sp3) with the rack, slides through  the small cylinder 2(Sc2) and small cylinder 3 (Sc3) in 7meter. As the rack is meshing with the pinions P1 & P2, it will rotate and through the gear train of the required gear ratio the power will be transferred to the rotor of the generator and by its rotation, electricity will be produced.

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

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 Flood Ebb
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

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
24×10 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
Boyle, Renewable Energy, Oxford University Press (2004)
Tester et al., Sustainable Energy, MIT Press, 2005

31. La Rance Tidal Power Barrage
The construction of this barrage began in The system used consists of a dam 330m long  and a 22km2 basin with a tidal range of 8m, it incorporates a lock to allow passage for small craft. During construction, two temporary dams were built on either side of the barrage to ensure that it would be dry, this was for safety and convenience. The work was completed in 1967 when 24, 5.4m diameter Bulb turbines, rated at 10MW were connected to the 225kV French Transmission network. 

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

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 Barrage Layout
Boyle, Renewable Energy, Oxford University Press (2004)

41. Severn Barrage Proposal Effect on Tide Levels
Boyle, Renewable Energy, Oxford University Press (2004)

42. Severn Barrage Proposal Power Generation over Time
Boyle, Renewable Energy, Oxford University Press (2004)

43. Severn Barrage Proposal Capital Costs
~$15 billion
(1988 costs)
Tester et al., Sustainable Energy, MIT Press, 2005
Boyle, Renewable Energy, Oxford University Press (2004)

44. Severn Barrage Proposal Energy Costs
~10¢/kWh
(1989 costs)
Boyle, Renewable Energy, Oxford University Press (2004)

45. Severn Barrage Proposal Capital Costs versus Energy Costs
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
Blue Energy Power System - For large scale power production, multiple turbines are linked in series to create a tidal fence across an ocean passage or inlet. These are large scale, site specific, custom engineered energy installations which will vary in size and output by location. These structures have the added benefit as a transportation solution.
Mega Power System - A scaled-up version of the Blue Energy Power System, the mega class is a tidal fence capable of producing thousands of megawatts of power. These tidal fences can be many kilometers long and can operate in depths of up to 70 metres.
Boyle, Renewable Energy, Oxford University Press (2004)

48. Promising Tidal Energy Sites
Country
Location
TWh/yr GW
Canada
Fundy Bay 17
4.3
Cumberland 4
1.1
USA
Alaska
6.5
2.3
Passamaquody
2.1 1
Argentina
San Jose Gulf
9.5 5
Russia
Orkhotsk Sea
125 44
India
Camby 15
7.6
Kutch
1.6
0.6
Korea 10
Australia
5.7
1.9

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

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
The potential energy of a set of waves is proportional to wave height squared times wave period (the time between wave crests). Longer period waves have relatively longer wavelengths and move faster. The potential energy is equal to the kinetic energy (that can be expended). Wave power is expressed in kilowatts per meter (at a location such as a shoreline).
The formula below shows how wave power can be calculated. Excluding waves created by major storms, the largest waves are about 15 meters high and have a period of about 15 seconds. According to the formula, such waves carry about 1700 kilowatts of potential power across each meter of wavefront. A good wave power location will have an average flux much less than this: perhaps about 50 kw/m.
Formula: Power (in kw/m) = k H2 T ~ 0.5 H2 T,
where k = constant, H = wave height (crest to trough) in meters, and T = wave period (crest to crest) in seconds.

57. Global Wave Energy Averages
Average wave energy (est.) in kW/m (kW per meter of wave length)

58. Wave Energy Potential Potential of 1,500 – 7,500 TWh/year
10 and 50% of the world’s 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.”
Potential world-wide wave energy contribution to the production of electricity is estimated by IEA (International Energy Agency) to be between 10 and 50% of the world’s yearly electricity demand of 15,000 TWh
A recent study by the DTI and Carbon Trust in UK is stating some 200,000 MW installed wave and tidal energy power by 2050 which with a load factor of 0.35 is resulting in a power production of 6 TWh/y. Independent of the different estimates the potential for a pollution free energy generation is enormous

59. Wave Energy Technologies

60. Wave Concentration Effects
Boyle, Renewable Energy, Oxford University Press (2004)

61. Tapered Channel (Tapchan)
Another promising type of wave energy power plant is a shoreline-based system called the Tapered Channel (Tapchan).  The principle here is capital intensive yet has potential due to its ruggedness and simplicity.  A tapering collector funnels incoming incoming waves in a channel.  As the wave travels down the narrowing channel it increases in height till the water spills into an elevated reservoir.  The water trapped in the reservoir can be released back to the sea similar to conventional hydroelectric power plants to generate electricity [1].  The advantage of this particular system lies in its ability to buffer storage which dampens the irregularity of the waves.  However, the Tapchan system does require a low tidal range and suitable shoreline topography -limiting its application world-wide. A demonstration prototype of this design has been running since 1985 and plans are under consideration to build a commercial scale plant in Java [8].

62. Oscillating Water Column
The Oscillating Water Column generates electricity in a two step process. As a wave enters the column, it forces the air in the column up the closed column past a turbine, and increases the pressure within the column. As the wave retreats, the air is drawn back past the turbine due to the reduced air pressure on the ocean side of turbine.
Much research is occurring internationally to develop oscillating water columns which require less stringent siting conditions, including the OSPREY and floating columns, such as the Japanese Mighty Whale

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
Another notable example of an OWC is the “Mighty Whale.”  It is the world’s largest offshore floating OWC and was launched in July 1998 by the Japan Marine Science and Technology Center.  This prototype, moored facing the predominant wave direction, has a  displacement of 4,400 tons and measures 50m long.  The Mighty Whale has three air chambers that convert wave energy into pneumatic energy.  Wave action causes the internal water level in each chamber to rise and fall, forcing a bi-directional flow over an air-turbine to generate energy.  The resulting electricity is supplied mainly to the nearby coastal areas.  Storage batteries onboard ensure that electricity is available even during periods of reduced wave activity.  It is projected that a  row of such devices could be used to supply energy to fish farms in the calm waters behind the devices, and aeration/purification of seawater [7].

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)

68. Ocean Wave Conversion System
This technology builds upon SARA's pioneering Ocean Wave Energy Conversion system, awarded US Patent 5,136,173; Unlike alternative concepts that make use of cumbersome intermediate mechanical stages, SARA's approach uses direct conversion of mechanical fluid energy into electricity, via a highly efficient magnetohydrodynamics (MHD) process.
Product:
Rapidly-deployable Wave-powered MHD Electric Generator for the US Navy
Low-cost commercial power for coastal communities.
Benefits:
Almost no moving parts. No gears, no levers, no turbines, no drive belts, no bearings, etc.
Direct, local, and efficient conversion of fluid motion into electricity, with no intermediate mechanical stages.
Highly-compatible with very-strong, but slow-moving, driving forces (ocean waves, for example).

69. Wave Conversion System in Action

70. Wave Dragon Wave Dragon Copenhagen, Denmark http://www.WaveDragon.net
Click Picture for Video

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.

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

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
High capital costs for initial construction [9] to resist exposure to strong wave forces, storms, and corrosion [10];
Wave energy is an intermittent resource [2];
Requires favorable wave climate.  The highest concentration of wave energy occurs between the latitudes 40° and 60° in each hemisphere, which is where the winds blow most strongly.  Latitudes of around 30° of the equator due to the regular trade winds may also be suitable for exploitation of wave energy [11];
Offshore wave energy systems require investment power transmission cables for electrical connections to shore [11];
Degradation of scenic ocean front views from wave energy devices located near or on the shore, and from onshore overhead electric transmission lines [10];
Potential interference with other uses of coastal and offshore areas such as navigation, fishing, and recreation if not properly sited [2];
By reducing the height of waves they may affect beach processes in the littoral zone [2].

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
Ocean waves have the potential to contribute up to one TW to the global energy supply. 
The problems associated with the intermittence of wave energy can be smoothed by integration with the general energy supply system. 
Many different wave power plants, some of them multi-purpose, have been proposed, assessed, and cost-estimated
With the development of large-scale demonstration and commercial power plants underway, wave energy will begin to play an increasing role in complementing other renewable and conventional energy technologies to meet global needs. 

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