Origin of Petroleum 



295 



150,000 times faster than it was formed. 

 The sunlight required to make this petro- 

 leum also had about 10 million times the 

 energy that is presently being recovered as 

 petroleum. Nature's storage of the solar 

 energy has been inefficient, but it is in a 

 form that is cheaper and easier to tap and 

 use than solar energy at our present level of 

 technology. Some idea of the magnitude of 



solar energy is provided by a computation 

 of Ayres and Scarlott (1952, pp. 187, 313), 

 who showed that the entire stock of com- 

 bustibles on Earth (wood, coal, petroleum, 

 natural gas, oil shale, uranium, and thorium) 

 can altogether provide only as much heat 

 as is received by Earth from the sun in 

 3 days. 



