Electric Furnace

Smelt ore without ever feeding wood into it. Once power is wired in, the furnace keeps cooking while you are out farming, and nobody has to run home to top up a fuel slot.

Coming from a regular furnace, the swap has a cost you only notice later. Burning wood leaves charcoal behind, and charcoal goes into every batch of gunpowder. An electric one burns nothing, so it gives you none. Most groups keep it for metal ore and leave sulfur to the wood burners, where the charcoal pays for itself.

Your power source decides how well this goes. A small generator gives a steady 40 power but eats low grade fuel, which brings the fuel problem back in another form. Solar costs nothing in daylight and needs a battery at night. The Industrial Electric Furnace has an identical row, so either one does the job.