1. Energy and the Environment
Ocean Energy
Energy and the Environment

2. Tidal Energy
Tides are caused by the gravitation pull on the oceans caused by the moon (and to a small amount the Sun)
“Spring Tides” are extra big since they occur when the Sun and moon are in alignment.

3. Tidal Energy
Early 1960’s France constructed a barrage across La Rance tidal estuary.
At 240 MW it is the largest tidal energy facility in the world.
Second is 18 MW and is located in Annapolis Royal, Canada.

4. Annapolis Royal Tidal Power Plant

5. Tidal Energy

6. Tidal Energy: Future Potential
Optima sites are scarce, only about two dozen location around the world
Only Maine and Alaska in the USA have sufficient tide oscillations to be effective.
Proposed project in the UK, Severn Estuary, 8640 MW, 5% on the UK power consumption in 2002

7. Tidal Energy: Future Potential
Benefits
Drawbacks
Emission free
Predictable
Reliable
Once built, energy source is free.
Remote and limited global distribution of the tidal resource.
Produce electricity intermittently
High capital costs
Environmental concern are similar to conventional hydroelectric energy

8. Wave Energy
Waves are created by the movement of the wind over the ocean.
Since the Sun causes wind, wave energy is a form of solar energy.
It has been estimated that wave technology could feasibly fulfill 10% of the global electricity supply if fully developed.

9. Wave Energy
Waves lose 60% of their energy by the time they reach the shore
But offshore energy production requires sub-sea transmission lines to distribute the electricity. This is very costly

10. Example of Wave Systems
Pacific Northwest Generating Cooperative
Magnets are secured to the ocean floor, copper coils move up and down with the waves.

11. Example of Wave Systems
Pelamis Wave Energy Converter
Pressurized oil drives a hydraulic ram which turns a generator
Prototype in Scotland and in Portugal, but now offline.

12. Example of Wave Systems
Seabased AB system
Generator anchored to the seabed and a floating buoy rises and falls with the waves

13. Example of Wave Systems
Oyster wave energy converter by Aquamarine power
Testing being done in the UK and Scotland

14. Example of Wave Systems
Waves move a turbine and generator by forcing a column of air up and down.

15. Wave Energy: Future Potential
The US has a great deal of wave potential, but Europe has taken the lead in wave energy.

16. Wave Energy: Future Potential
Benefits
Drawbacks
Generally predictable and constant
Waves have much more kinetic energy than wind due to its density
Emission free
Currently more expensive
Eyesore and may disrupt the natural movement of sediment.

17. Marine Current Systems
Lunar gravitation as well an thermal differences and water density influence TIDAL STREAMS or strong marine currents
Systems resembled wind turbines but underwater. Rotating blades are used to convert the kinetic energy in water currents into electricity
Can be floating or anchored to the seabed

18. Marine Current Systems: Future Potential
2003 Norway completed the world’s first commercial power plant using marine current technology.

19. Marine Current Systems: Future Potential
Benefits
Drawbacks
Predictable in both timing and quantity
Virtually non intermittent, only in some places ceasing during the turning of the tides.
Since they are modular, they can be scaled up when more capital becomes available
Little “eyesore” factor
Early studies show little environmental or ecological footprint
Still more expensive than using fossil fuels
Harsh marine environment makes maintenance both difficult and necessary.

20. Ocean Thermal Energy Conversion
The ocean stores way more energy from the sun than we use on a daily basis
If we could harness just a fraction of that energy we would be able to offset fossil fuel use substantially
Must be a temperature differential of 36oF
Much potential in tropical and island locations

21. Closed Cycle: Ammonia

22. Open-Cycle

23. Can be land based or floating

24. OTEC: Future Potential

25. OTEC: Future Potential
Benefits
Drawbacks
Could serve as ideal base load energy source.
Provide other attractive services such as desalination of sea water and air conditioning.
Little notable impact on marine ecosystem
Only certain places have a large enough temperature gradient for it to be efficient
Same challenges as other marine technologies – susceptible to extreme weather.
Technology is still far from being cost effective