Mercen X has it right, here's the script:

Rufus: Now then...... We're faced with two issues. 1: Destroy Meteor. 2: Remove the barrier around North Cave and defeat Sephiroth. Any ideas?

Heidegger: Gya haah hah hah! We already solved the first problem! Meteor will soon be smashed to bits! The plan has already been put in motion. Namely, to collect Huge Materia from each region.

Rufus: Well......

Scarlet: Huge Materia is a high density special type of materia made through a special compression process in Mako reactors. The energy extracted from it is 330 times the strength of normal materia. Ha, ha, ha! How about that!? We will gather all the Huge Materia together and ram it into Meteor. That will cause a huge explosion!! Reducing Meteor literally to bits.

Rufus: You're going to ram Meteor? Do you think we have the technology to do it?

Scarlet: Don't worry about that! More importantly, we've got to collect Huge Materia from each area.

Heidegger: We've already collected materia from Nibelheim. All that's left is "Corel" and "Fort Condor", I've already dispatched troops to Corel. Ghaa haah hah hah!
Its not a fuel, but it is not attached to a bomb, it is just implied the Huge Materia is the most important element cause it will have the destructive power to take down meteor, theoretically.