psr*<"SBT>W5?TO?r>™^^^ - - - pout 7-T-" M ~r~ ~,ct~:-t,- t — rT.-^--"mTOarwfwiTi. 



The other fuels can be synthesized in various ways, at various 

 costs. Synthetic gasoline appears to require the most steps and provides 

 no benefits in terns of redaced air pollution over the present oil 

 derivative. Kethar.e, Eethaaol, and ethanoi are all presently being 

 studied and have been shown to be cleaner burning than gasoline 13, 4, 

 1]. Methane can be compressed or liquified and as such is subject to 

 all the problems inherent with pressurized gas or cryogenic liquids. In 

 terms of energy densities methanol and ethanol will take up 2.2 and 1.7 

 times more weight and 1.9 and 1.5 times more volume than gasoline. This 

 appears to be their only major p rob lea though, and several recent arti- 

 cles indicate that prices will shortly be cospetitive with gasoline [3, 

 41. 



The last major contender as a synthetic fuel is hydrogen. Hydrogen 

 is a major constituent in many of the other fuels and in most cases oust 

 be supplied during their synthesis processes. Hydrogen is more of a 

 •miversal fuel than the others. It can be burned efficiently and with 

 very low emissions in either internal or external combustion engines. 

 It can be used for cooking and heating; and since the exhaust products 

 are water and air and would not need to be vented, one should expect a 

 heating efficiency of 100%. Finally, it is an excelleut fuel for fuel 

 cells. In short, hydrogen is the superior fuel. It can be prepared in 

 numerous ways, including electrolysis [5], steam reformation, and chemi- 

 cal cracking [6J. Its only major problem is its storage. 



Four methods presently exist for storing hydrogen: 



1. It can be stored as gas in huge containers at ambient tesspera- 

 tures and low pressures. 



2. It can be stored as gas compressed to very high pressures of 

 the order of 2,000 to 7,500 ps\a (13S to 510 atmospheres). 



3. It can be liquified to reduce further the storage volume. 



U. It can be stored chemically bonded in metallic and intermetallic 

 hydrides. 



The first case would serve jell where space is unimportant. In 

 situations where mobility is important, or where space is limited the 

 volume would have to be smaller. The pressurized hydrogen storage does 



R not present a significant improvement over the first storage method 



because of the excessive weight of pressure vessels required for storage, 

 and the amount of energy needed to compress the hydrogen. Liquifying 

 hydrogen is a good method in terms of weight and volume, but tt requires 



|J - a large expenditure of energy to first liquify it and chen, when needed, 

 to gasify it (an amount of energy equivalent to abo.it one-third of the 

 energy stored in the hydrogen). Further disadvantages are the large 

 amount of equipment needed to transport and transfer the cryogenic 

 hydrogen and the short period that liquid hydrogen can be stored before 

 it vaporizes in its container and must be vented. 



