As the title says, you can get infinite EMC by converting gunpowder into alchemical fuel, and then crafting up into aeternalis fuel, before selling aeternalis fuel for gunpowder, and doing it all over again. This is because the EMC value of each fuel type doubles the amount of EMC from the ingredients, leading to an exponential effect. I turned effectively 2 gunpowder into over 10 stacks of diamond blocks within a couple of minutes