Vampire: The masquerade

They sort of are in a way, but only as a source of quick and easy fire. In this diagram, the blood and holy water are both consumed at a decent rate, making the engine actually powered by them. You could say it's powered by the collapse and regeneration of the vampire, but that's a perpetual and unavoidable side-effect of putting the holy water and blood into the chamber, much like the explosion in ICEs are the side effect of putting gas into a chamber and then sparking it.