Fuel is a required element for an array of tasks from smelting to alchemy.
Wood is a basic fuel that is likely to be the easiest to come across. It can be acquired by chopping down any tree.
There is a variety of different wood that can be acquired, each owing to their own specific type of tree.
Planks and logs both smelt 1.5 items.
Charcoal is an alternative to coal. In Rebirth of The Night, it is created using a Kiln.
You will need a Log Pile (9 logs) which is placed into the top of your Kiln and is fueled using alternative fuel, such as another log.
Once complete you will be provided with a charcoal block which can be then placed onto a Multipurpose Stone Anvil and hit with a stone hammer to provide Charcoal.
Each Charcoal smelts 8 items, and each Charcoal block smelts 80 items.
Pre-Kiln Charcoal can be obtained using pit burning as demonstrated in the following video:
Coal is the most common fuel. It is acquired by mining coal ore which can be found in mines and above the surface.
When mining a coal ore, you will be provided with a single coal item, this can be used as both a fuel and also a crafting element. When using a pickaxe with fortune, the number of coal you will receive grows.
Each coal smelts 8 items, and each coal block smelts 80 items.
Wax is an effective fuel found via apiaries. Queen bees produce wax combs and honeycombs; the former of these can be used in a Mill Stone to produce wax. Honeycombs also produce wax when put in a Mill Stone, but they produce less.
Wax is usually produced in massive quantities and has no other particularly useful uses other than fuel.
Each wax smelts 4 items, and each wax block smelts 40 items.
Ash is a plentiful fuel found in the Nether, or it can be obtained via Pit Burning.
Each piece of ash smelts 2 items.