From Fallen London Wiki

Coal, dug from Zee-cliffs or imported from Hell.

[If you run out of fuel, you will drift helplessly.]

Wiki note: see this in Sunless Sea, or in the Iron Republic.

This item can no longer be obtained. For details, see Sunless Sea.

See here for a list of how to obtain this item, or click here to show them.

This item has no documented uses.

Wiki note: Could be purchased with Echo (Harbour Provisioners) at the now retired shop Harbour Provisioners