Let me now summarize three somewhat obscure marine energy options, starting with Tidal Energy:
The great advantage of tidal energy is that it is totally predictable, and in some portions of the world, the daily tides, where crests occur every 12 hours and 25 minutes, caused by the revolution of the moon around Earth, and our planet around the Sun, can exceed 50 feet. Tidal movement has actually slowed the rotation of Planet Earth over the past half billion years or so from 22 to 24 hours. Why do some locations have such tides and others closer to a foot or less? Well, good question, and the answer is that astronomical factors, shape and depth of basins and inlets and barometric pressure fluctuations combine to create these differences. Glad you asked. Hope you now know why.
Tidal energy has been used since the 11th Century when small dams were built at the coastline for water to turn wheels to mill grains. If an estuary or fjord (natural reservoir) of sufficient size is at the coastline, it then becomes a relatively simple matter of placing a turbine where the tides come in and out. The 240 MW Rance River facility (1966) in France has been operating for four decades, China has several facilities producing a total of more than 11 MW. In Canada, the Annapolis Basin generator of Nova Scotia (1984) produces 20 MW.
There are ample locations in Canada {Bay of Fundy, where tides are 17 meters (56 feet), particularly Minas Basin, showing potential for 7,000 MW between New Brunswick and Nova Scotia, where vertical axis marine blades are being contemplated}, United Kingdom {Severn, 15 meters (49 feet) for 8640 MW}, Russia {Mezenskaya, where a tide of 10 meters (33 feet) show prospects for a 15,000 MW system, and Penzhinskaya Bay, 6 meters (20 feet) for 50,000 MW}, Korea {where Incheon “only” has about a 5 meter (16 feet) tide, but has completed a 480 MW design}, and Turnagain Arm, Alaska {7.5 meters (24.6 feet) for 6500 MW}. At a cost of $250 million, equipment has been ordered for the 254 MW Shinwa Tidal Power Plant off the South Korean coast, while the city of Incheon announced their intent to connect four islands to harness 812 MW at a cost of $1.9 billion.
The reality is that this is a limited option. A couple of nations will no doubt begin to build rather elaborate systems, but this is not a world saving option.
The great advantage of tidal energy is that it is totally predictable, and in some portions of the world, the daily tides, where crests occur every 12 hours and 25 minutes, caused by the revolution of the moon around Earth, and our planet around the Sun, can exceed 50 feet. Tidal movement has actually slowed the rotation of Planet Earth over the past half billion years or so from 22 to 24 hours. Why do some locations have such tides and others closer to a foot or less? Well, good question, and the answer is that astronomical factors, shape and depth of basins and inlets and barometric pressure fluctuations combine to create these differences. Glad you asked. Hope you now know why.
Tidal energy has been used since the 11th Century when small dams were built at the coastline for water to turn wheels to mill grains. If an estuary or fjord (natural reservoir) of sufficient size is at the coastline, it then becomes a relatively simple matter of placing a turbine where the tides come in and out. The 240 MW Rance River facility (1966) in France has been operating for four decades, China has several facilities producing a total of more than 11 MW. In Canada, the Annapolis Basin generator of Nova Scotia (1984) produces 20 MW.
There are ample locations in Canada {Bay of Fundy, where tides are 17 meters (56 feet), particularly Minas Basin, showing potential for 7,000 MW between New Brunswick and Nova Scotia, where vertical axis marine blades are being contemplated}, United Kingdom {Severn, 15 meters (49 feet) for 8640 MW}, Russia {Mezenskaya, where a tide of 10 meters (33 feet) show prospects for a 15,000 MW system, and Penzhinskaya Bay, 6 meters (20 feet) for 50,000 MW}, Korea {where Incheon “only” has about a 5 meter (16 feet) tide, but has completed a 480 MW design}, and Turnagain Arm, Alaska {7.5 meters (24.6 feet) for 6500 MW}. At a cost of $250 million, equipment has been ordered for the 254 MW Shinwa Tidal Power Plant off the South Korean coast, while the city of Incheon announced their intent to connect four islands to harness 812 MW at a cost of $1.9 billion.
The reality is that this is a limited option. A couple of nations will no doubt begin to build rather elaborate systems, but this is not a world saving option.
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Current Energy
Ocean currents keep portions of the land warmer or colder, and can be utilized for energy. There is some tendency to consider current energy as tidal energy because the flow of currents is linked to tidal fluctuations, so proponents sometimes highlight this option to be ocean current energy. It is reported that a 2.4 MPH current is equivalent to a 22 MPH wind site. Both would be super locations.
Ocean currents keep portions of the land warmer or colder, and can be utilized for energy. There is some tendency to consider current energy as tidal energy because the flow of currents is linked to tidal fluctuations, so proponents sometimes highlight this option to be ocean current energy. It is reported that a 2.4 MPH current is equivalent to a 22 MPH wind site. Both would be super locations.
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The Gulf Stream carries 30 million cubic meters of water per second, more than 50 times the total flow of all the rivers, and has been estimated to have a potential of 25,000 MW. AeroEnvironment Company performed the Coriolis Project and proposed 242 170-meter diameter turbines to produce 10,000 MW. The Florida Current was used to produce 2 kW from a turbine suspended at 50-meter depth and UEK Corporation tested a 20 kW turbine in the New York City East River.
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Alexander Gorlov at Northeastern University in Boston speculated that the potential of the Gulf Stream was really 65,000 MW, and shared plans to construct a farm of 100 Gorlov helix turbines to generate 136 MW when the currents flow at 8.2 feet per second. He would like to generate hydrogen by electrolysis.
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The European Union has studied the potential of installing 100 vertical axis turbines in the Straits of Messina, between Sicily and Italy. In addition, the Japanese Kuroshiro and African Agulhas-Somali Streams have been suggested as having potential. My assessment: let’s see if anything is ever built of any magnitude.
Salinity Gradients
Salinity gradients can provide osmotic energy by utilizing the pressure difference at the boundary of the incoming freshwater flowing into the ocean, where a semipermeable membrane is utilized. The fresher the river water and saltier the ocean, the higher will be the efficiency.
The Dead Sea has an osmotic pressure differential with freshwater twenty times greater than that of seawater. Sidney Loeb has calculated that the cost of producing this energy there would be less than 6 cents per kilowatt hour. Another study tapping the Jordan River envisions a 66 MW power plant with capital costs of $9,000/kW and energy costs of $0.09/kWh.
Statkraft of Norway, in 2003 established the first laboratory dedicated to saltwater-power. In the U.S., the hydrocratic generator has been patented.
The problems are rampant, and include, imperfect membrane, high capital cost for plant installation and low efficiencies. Don’t hold your breath for any significant development.
Salinity Gradients
Salinity gradients can provide osmotic energy by utilizing the pressure difference at the boundary of the incoming freshwater flowing into the ocean, where a semipermeable membrane is utilized. The fresher the river water and saltier the ocean, the higher will be the efficiency.
The Dead Sea has an osmotic pressure differential with freshwater twenty times greater than that of seawater. Sidney Loeb has calculated that the cost of producing this energy there would be less than 6 cents per kilowatt hour. Another study tapping the Jordan River envisions a 66 MW power plant with capital costs of $9,000/kW and energy costs of $0.09/kWh.
Statkraft of Norway, in 2003 established the first laboratory dedicated to saltwater-power. In the U.S., the hydrocratic generator has been patented.
The problems are rampant, and include, imperfect membrane, high capital cost for plant installation and low efficiencies. Don’t hold your breath for any significant development.
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In Summary
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An excellent PowerPoint on all the above, including offshore windpower, can be accessed by going to GOOGLE and typing in Michael Robinson, ocean energy.
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Oil further sank to $123.26/barrel today. The Dow Jones Industrials ticked upwards by 21 points to 11,371. However, the world market tanked today. While this is supposedly related to their concerns about the U.S. economy, there are some ominous rumors about a subprime debacle, something of which I know not.
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Genevieve is now a hurricane at 75 MPH and is heading straight for Hawaii. But cooling and increasing shear should weaken her back to tropical storm status by Sunday. Anyway, this storm is still more than 2000 miles away.
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Dolly is now a remnant with winds of 30 MPH and headed for New Mexico. Brownsville suffered from a rainfall of 8.62 inches, while San Manuel got a foot. While nothing seems troublesome in the Atlantic Region, it should be remembered that Cristobal and Dolly justed popped up a day before they made landfall in North Carolina and Cancun, respectively.
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