OCEAN SCIENCES AND NATIONAL SECURITY 51 



fusion that occurs on the Sun. Should current research efforts succeed, 

 man would have a virtually inexhaustible store of energy, but the quest 

 is long and arduous. 



Still another possible source of energy from the sea has been pro- 

 posed by taking advantage of the difference in surface and bottom 

 temperature. It has been said that almost 35,000 times the existing 

 annual energy consumption of the world is delivered annually to the 

 Earth in the form of solar radiation and since most of the Earth's 

 surface is covered by ocean, a major portion of solar energy is absorbed 

 by the sea.^' 



The temperature at depths below which sunlight does not pene- 

 trate, on the order of 1,200 feet, is ordinarily around 40° F. In the 

 tropics, surface temperatures of 80-90° are common. TheoreticaUj', 

 this temperature difference could be utilized to drive a properly de- 

 signed turbme, but it would operate at low thermal efficiency because 

 the temperature differences are low. Quite obviously the amounts of 

 energy so extracted are unlimited. The major question is whether 

 such systems are economically attractive. 



Finally, there is the possibility of extraction of power fi'om tlw 

 twice daily rise and fall of the tides — such as has been proposed many 

 years ago for Passamaquoddy. 



It is natural that man should look for means of harnessing some of the power 

 of the tides for his own benefit and small tide mills have been operated in a few 

 suitable localities for centuries. ]\Iany plans for tidal power stations such as the 

 Severn Barrage scheme have been drawn up, but only one project has so far 

 reached the construction stage. This is the French scheme for the Ranee Estuary 

 in the Bay of St. Malo which is designed to have a capacity of 340 megawatts 

 and is due to be completed in 1960. The main difficulty in the development of 

 tidal power is that even with ha-ge tidal ranges, the hydraulic head a\-ailable is 

 comparatively small and large areas of tidal water would have to be enclosed, 

 at high capital cost.^^ 



E. METEOROLOGY AND CLIMATOLOGY 



The close relationship of the oceans to processes in the atmosphere 

 has been noted. Some additional details may make clearer why ques- 

 tions of weather forecasting and climate control depend on under- 

 standing of the sea. 



In the first instance, the Earth may be regarded as having a certain 

 heat budget which is related to energy gained from solar radiation 

 versus losses by reflection and reradiation in outer space. The differ- 

 ence, obviously more at the Equator than at the poles, is absorbed by 

 the atmosphere, by the land, and by the oceans; but, by virtue of 

 their physical properties and vast size, the oceans are the primary 

 recipients. This energj^ is then distributed by man^' processes; by 

 evaporation as the liquid water changes to vapor, and condensation as 

 it then drops as rain, or b}- circulation through both vertical and 

 horizontal ocean currents. 



The atmosphere itself contains energy and there is a continuous 

 flow back and forth between atmosphere and ocean at the interface. 

 Some of this exchange may be mechanical rather than thermal for 

 energy transmitted by surface winds to the sea apparently is the 

 mechanism largely responsible for surface currents. Scientists thus 

 attempt to develop equations in which aU of the elements in this 



3' "Design of a Sea Thermal Energy Power Plant" by Asa Snyder, Solar Energy, Dec. 1%9, pp. 49-54. 

 3' "The Oeeanic Tides," by K. F. Bnwden, The Nrw Scirntisl, ?-p\\t. 3, 1959, jip. .'^48-351. 



