I can't remember how to power an infernal furnace (I know it's bellows, but I don't remember if they need anything) but that sounds like a good idea
The infernal furnace smelts things for free. It goes faster, and provides bonus nuggets for vanilla ores if bellows are attached, and goes faster still when ignis essentia is supplied. Pre 4.2 you could just place jars of ignis nearby - I havn't tried the TC 4.2 essentia power network yet so can't comment on that.