For what it’s worth, % of non-plant life contribution to oil and gas deposits is probably extremely small. Most oil rich deposits are derived from algaes 

 Damn!  I need to find a less ethical source of fuel.  Do they make an engine that runs on virgins? 

 You can run a diesel engine on virgins. And lard. 

 Sweeeeeeeet 

 I suppose you'd have to pre-process them first.  *nudge* *nudge* *wink* *wink* 

 😂  

 Geothermal? Since folks used to throw ‘em into volcanos?