There is no real advantage.
It is to be able to continue the production of e.g. solid fuel with petroleum, when you aren't able to 'convert' heavy or light-oil to petroleum or you don't want to store other oil types. I think i might add something later, but the first idea was to eliminate the need to store these when not being able/wanting to store the other types but still produce the remaining type of oil.
I hope i could answer your question.
