Fermi Freeze - Batman Training's Last Fermi Problem

I like that fact that every reaction releases about 1.5eV of energy so let's make our last superheroic Fermi Problem one that uses that fact and then move on with the Batman Training.

What's the energy Mr. Freeze get's from diamonds (assuming it's a chemical process and not nuclear)?Diamonds are just carbon all bound together. Each carbon is bonded to 8 other carbons. (As always I'm just putting the simplest way of thinking about this together: Diamond is a crystal structure made of two fcc lattices).