Water, Water Everywhere … Only a Few Drops to Drink

LEANING RIGHT-Last week in my CityWatch piece ‘Southern California Looks to the Heaven’s for Help’ we looked at the amount of water on the earth and the fact that 97% is saline. Now, let’s talk efforts to convert the water and recover it for man’s use. Conversion requires energy but this will be provided by the ocean itself. This will be a perfect energy system. 

Ocean Current Energy-The constant flow of ocean currents carries large amounts of water across the earth’s oceans. Technologies are being developed so that the energy can be extracted and converted to usable power. 

Ocean waters are constantly on the move. Currents flow in complex patterns affected by wind, salinity, temperature of the ocean floor and the earth’s rotation. Most ocean currents are driven by wind and solar heating of surface waters near the equator, while some currents result from density and salinity variations of the water column. Ocean currents are relatively constant and flow in one direction, in contrast to tidal currents along the shore. 

Most ocean currents are driven by wind and solar heating of surface waters near the equator, while some currents result from density and salinity variations of the water column. Ocean currents are relatively constant and flow in one direction, in contrast to tidal currents along the shore. 

While ocean currents move slowly relative to typical wind speeds, they carry a great deal of energy because of the density of water. Water is more than 800 times denser than air. So for the same surface area, water moving 12 miles per hour exerts the same amount of force as a constant 110 mph wind. Because of this physical property, ocean currents contain an enormous amount of energy that can be captured and converted to a usable form. It has been estimated that taking just 1/1000th the available energy from the Gulf Stream would supply Florida with 35% of its electrical needs.

Ocean Current Energy Technologies 

There are a number of different current technology concepts under development. Prototype horizontal axis turbines, similar to wind turbines, have been built and tested, and over the next 5 to 7 years would be the most likely commercial development scenario. 

Although ocean current technology is still in its early stages of development, several tidal and in-stream current turbine applications are near commercialization. These devices take advantage of the daily tidal cycles in near-shore ocean environments. 

Technical Challenges-For ocean current energy to be utilized successfully at a commercial scale, a number of engineering and technical challenges need to be addressed, including: 

● avoidance of cavitations (bubble formation); 

● prevention of marine growth buildup; 

● reliability (since maintenance costs are potentially high); and 

● corrosion resistance.

Because the logistics of maintenance are likely to be complex and the costs potentially high, system reliability is of particular importance. At present no open-ocean current                                          turbines are deployed in U.S. waters—this technology is truly in its infancy. However, there is interest in testing prototype turbines in U.S. waters in the near future, particularly off the coast of Florida. 

The big challenge will not be capturing the energy of the ocean currents. It will be using the energy to convert the salt water to fresh water and then transporting the fresh water for mankind use. 

Most current desalination efforts produce nickel and dimes worth of drinkable water. Using the earth’s currents will produce massive amounts of clean water.

It will be a perfect system. 

 

(Kay Martin is an author and a CityWatch contributor. His new book, Along for the Ride, is now available. He can be reached at  [email protected] This email address is being protected from spambots. You need JavaScript enabled to view it. )-cw   CityWatchVol 12 Issue 98Pub: Dec 5, 2014 

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