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The final BsiLcr?, the storage of hydrogen in cbamical bond3 In 

 metallic sad interaetallic hydrides, shows great prcaise for avoiding 

 the problems of the other three csathcda. The Billies 3 Eaergy Research 

 Corporation In Provo, Utah [7, 6] has recently demonstrated an experi- 

 mental ircr-«Eitaalu3 hydride storage unit. This unit absorbs hydrogen 1 

 at pressures of 150 to 1,030 psla (10 to 70 otcoepherea) and at tempera- 

 tures of 100 F to 150 F. During the absorption of the hydrogen, heat is 

 given off. Then, as hydrogen is burned in en autcscbile engine, for 

 instance, the exhaust heat from the combustion is used to release the 

 hydrogen froxa its hydride bonds. Ircn-titaniua hydride is now a proven 

 energy storage material. 



Figures la, lb, and 1c compare pressurised, liquified, and metal- 

 h>dride hydrogen storage systeus in terms of extimated cost, weight, and 

 volume, respectively. Uhere voluse is a consideration the metal hydrides 

 are definitly applicable systems. Uhere weight is the prominent consid- 

 eration liquid hydrogen appears to be the best choice. Where cost Is the 

 major factor it is uncertain which system would be best. 



One further advantage of metal hydrides is that the energy used to 

 dissociate the hydrogen frca the hydride is not lost but can be utilized 

 during the recharge period to heat buildings or water or to provide the 

 heat needed for an absorption cooling system. Thus, mere of the energy 

 stored in the hydrogen can be used with a hydride system than would be 

 used if the hydrogen were merely burned and the products exhausted. 

 Less energy is used to cocpress the hydrogen in the hydride system than 

 in the high pressure systems because the pressures are lover. Finally, 

 the hydrides can store hydrogen indefinitely as long as they are isolated 

 from deactivating substances. This is much superior to the liquified 

 hydrogen schemes which can only claim to store hydrosen for a few days 

 [7). 



In short, metal hydrides appear to be useful energy storage vehicles 

 in certain situations. Requirements such as utility life, shelf life, 

 maintenance and cost effectiveness most be considered for each application. 

 Once these requirements are known, the proper fuel and storage vehicle 1 



can be chosen. The following sections of this report attempt to present 

 a general overview of the hydrides available and how they meet the 

 requirement categories mentioned above. 



! 



CLASSIFICATION OF HYDRIDES 



1 

 I 

 A short summary of the classification of metal hydrides, is included m . 

 here only for completeness. More detailed descriptions are given in 

 several publications, including References 9 and 10. Generally, hydrides 

 are classified by the nature of the hydrogen bond Into three principal 

 categories: 



- covalent or volatile 



- saline or ionic 



- metallic. 



a 



As In the Billings demonstration. 



