Friday, May 1, 2009

NYT presents a 1920's idea as new technology

Good old NYT, life would be boring without them. They ran a big spread on ocean thermal power, presenting it as the answer to the energy problem and a promising new technology. Of course the highly educated Times men didn't know that ocean thermal power was pioneered in the 1920's by Georges Claude, a wealthy French scientist. Claude built a test plant on the shore of Cuba in 1929 which worked but produced little power. He built a sea borne ship mounted unit in 1934 which didn't work much better. In the end Claude gave up and scuttled his ship in a place where the ocean was especially deep.
The concept of ocean thermal power is fairly simple. You build a steam engine that runs on a fluid that boils from the heat of the warm surface water, and condenses in the coolth of the deep bottom water. This requires a long pipe reaching down to the cold bottom water layers. This pipe has been the bane of ocean thermal power experiments. Either it breaks in a storm, or the feed water pump uses up most of the output of the plant. Heat engines work off a thermal difference. The greater the temperature difference the more power the engine will deliver. Old fashioned steam locomotives worked off a temperature difference of 300 degrees F.
Warm tropical ocean water might be 80 degrees F. The cold bottom water is never colder than 32 degrees F, yielding a temperature difference of only 50 degrees F at the most favorable locations, like the Carribbean. Off the New England coast, the ocean water never goes above 50 degrees F, reducing the temperature difference to a mere 20 degrees F.
Since Claude's experiments 70 years ago, other's have tried, but no one has been able to squeeze enough power out of a 50 degree temperature difference to make the effort worth while. We are talking steam engines here. Steam engines have been well understood for better than a hundred years. It is unlikely that some intrepid inventor will make a great breakthru in steam engine technology.

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