Can Heimerdinger use his tap ability for 1 damage if he's not on a battlefield, when copying Renata's exert ability?

Ruling: Heimerdinger can use the ability even when not on a battlefield. He copies Renata's exert ability but does not copy her battlefield restriction.

Nuances:

• You still have to pay the cost to use the copied ability
• Only the restriction (battlefield requirement) is not copied, the ability itself including its costs is copied