# Lightning and propane tanks

**URL:** <https://boards.straightdope.com/t/lightning-and-propane-tanks/454162>\
**Category:** Factual Questions\
**Created:** [June 25, 2008, 3:25am UTC](https://boards.straightdope.com/t/lightning-and-propane-tanks/454162 "2008-06-25T03:25:06Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![andy77494](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@andy77494](https://boards.straightdope.com/u/andy77494)\
**Post date:** [June 29, 2008, 5:24am UTC](https://boards.straightdope.com/t/lightning-and-propane-tanks/454162/21 "2008-06-29T05:24:49Z")

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[QUOTE=Santo Rugger]  
The heat of combustion is about 50\* MJ/kg for propane, compared to 4.652 MJ/kg for TNT. This means that, with perfect efficiency, propane would have an equivalence of 10.75.  
[/QUOTE]

That is assuming that the propane is premixed with air (oxygen) in stoichiometric amounts for the calculation here - which may not be correct. Combustion of propane is not quite the same as the detonation of TNT. Actually if you are looking at detonation you should look at energy (heat) released per second rather than total energy released. All that propane is not going to catch fire instantly.

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