Coalfuel Cells can be used to fill Empty Fuel Cans
Coalfuel Cells can be used with the Canning Machine to fill Empty Fuel Cans that can then be used in Generators to produce EU. 6 Coalfuel Cells are required to fill an Empty Fuel Can.
Coalfuel cells also the the Longest burning fuel in a computercraft turtle.
Coalfuel Cells are made by putting a Hydrated Coal Cell in a powered Extractor.