▁nap alm ▁was ▁employed ▁in ▁July ▁ 1 9 4 4 , ▁towards ▁the ▁end ▁of ▁the ▁Second ▁World ▁War ; ▁although ▁its ▁use ▁did ▁not ▁gain ▁public ▁attention ▁until ▁the ▁Vietnam ▁War . ▁Mol ot ov ▁co ck t ails ▁were ▁also ▁used . ▁ ▁Use ▁as ▁fuel ▁ ▁Setting ▁fuel ▁a fl ame ▁releases ▁us able ▁energy . ▁Wood ▁was ▁a ▁pre histor ic ▁fuel , ▁and ▁is ▁still ▁vi able ▁today . ▁The ▁use ▁of ▁foss il ▁fu els , ▁such ▁as ▁pet role um , ▁natural ▁gas , ▁and ▁coal , ▁in ▁power ▁plants ▁supplies ▁the ▁vast ▁majority ▁of ▁the ▁world ' s ▁electric ity ▁today ; ▁the ▁International ▁Energy ▁Agency ▁states ▁that ▁nearly ▁ 8 0 % ▁of ▁the ▁world ' s ▁power ▁came ▁from ▁these ▁sources ▁in ▁ 2 0 0 2 . ▁The ▁fire ▁in ▁a ▁power ▁station ▁is ▁used ▁to ▁heat ▁water , ▁creating ▁steam ▁that ▁drives ▁tur b ines . ▁The ▁tur b ines ▁then ▁spin ▁an ▁electric ▁generator ▁to ▁produce ▁electric ity . ▁Fire ▁is ▁also ▁used ▁to ▁provide ▁mechanical ▁work ▁directly , ▁in ▁both ▁external ▁and ▁internal ▁comb ust ion ▁engines . ▁ ▁The ▁un burn able ▁solid ▁remains ▁of ▁a ▁comb ust ible ▁material ▁left ▁after ▁a ▁fire ▁is ▁called ▁cl ink er ▁if ▁its ▁mel ting ▁point ▁is ▁below ▁the ▁fl ame ▁temperature , ▁so ▁that ▁it ▁f uses ▁and ▁then ▁solid ifies ▁as ▁it ▁co ols , ▁and ▁ash ▁if ▁its ▁mel ting ▁point ▁is ▁above ▁the ▁fl ame