Thermal Conversion allows you to take any energy system that supports smelting and convert into solid fuel, allowing you to move it into any other typical coal type generator.
Start out by crafting a Thermal Cell.
Once you pick up enough thermal cells, you may compress them using the same formation as with a chest or furnace.
All of these can be used to smelt items, equal to the amount of fuel put in.
You can even get lava.
You lose some energy, (lava only smelts 100,) but for many applications it is well worth it.
From Botania, to Thermal Expansion, and now to Tinkers Construct. Thermal Conversion has it covered.
I hope you enjoy.
(All images generated using the Roughly Enough Items export tool).