While "power" is a noun that refers to the ability to do something, there is no common English word that functions as its abstract noun form.
You could use other words to express the concept of "powerness", depending on the context:
* Power: This can be used directly in many contexts, like "the power of nature" or "the power of love."
* Influence: This emphasizes the ability to affect or change something.
* Might: This refers to strength or force.
* Potency: This describes effectiveness or strength.
* Domination: This implies control and authority.
If you are trying to express a specific concept related to "power," it might be helpful to provide more context so I can suggest more precise alternatives.