I wouldn't make the mistake of thinking about APD as a "chemical company". It's often placed in the category of basic materials, a much better classification. Dow is most certainly a chemical company, DuPont is (although less than it once was), and BASF goes so far as to bill themselves as "The" Chemical Company. APD sold off the vast majority of their "chemical" businesses..... keeping the word in their name seems a bit of a confusing misnomer now.
What APD uses alot of is electricity, a fraction of which is generated from natural gas. If they're "saving" from lower gas costs it doesn't seem to be showing up in their margins and on the bottom line. Why that is is a complicated story.
Surely almost all of APD's lomg term supply contacts for H2 (and any other product) have escalation clauses for energy costs pass through to the customer, so they are usually covered there. However, that cost could affect volumes if the customers find alternative solutions.