Au contraire. Newman was a serious student of Aristotle, and he had a real understanding of potency and act, only under different terms. Unlike Sillem, Newman was not formed in the post-Leonine Thomist tradition; he read Aristotle at Oxford in Greek, and therefore familiarized himself with dunamis and energeia, rather than the potentia and actus of Thomistic Aristotelianism. Furthermore, Newman discovered the mechanics of these concepts in Aristotle's ethical works--the Ethics, the Rhetoric, and the Poetics, rather than the Physics, Metaphysics, and De Anima, which have been the staple for Catholic Aristotelians of the last hundred years. Given these two facts, Newman's way of speaking about dunamis and energeia (especially the latter) hasn't ever really caught the attention of intellectual Catholic readers.
Listen more closely. If I am right, Newman commonly--in fact, most of the time--uses the "energy" and "energize" with Aristotle's energeia in the background. I think, actually, that it fundmentally structures the way Newman thinks of the human person, in great part because energeia is a crucial structural idea within ethos, or character, as Aristotle describes it in these works. Energeiai are the ways of being-at-work--the activities--that carry out the principles (archai) of one's character in real time; when habituated, they become the living, active facets of one's character, defining a person for the world, at least insofar as his "second nature"--his ethos--is concerned. This view of human character, I want to say, is foundational for Newman's view of personhood: in it, ethos is defined by energeiai according to certain archai. Listen more closely to the way Newman speaks of "character," "energy," and "principle," and I think you'll find that his usage usually fits into this Aristotelian structure.
While I could really tire us all out with proof-texts, I will fall back on two or three passages that demonstrate Newman's familiarity with Aristotelian energeia, and show his proclivity for thinking of "energy" with it in mind. One is in "Professors and Tutors," from Rise and Progress of Universities. In that essay, he gives a free translation of Aristotle's definition of virtue, according to which anxiety" he felt "when composing (e.g. a sermon or any[thing] else)—something, viz, which I wish to have got thro’ which is an irritation while it lasts, and which has its enjoyment and telos in the ergon produced, which is subsequent to the energeia" (LD 3.254-55). Here Newman depicts his own character on Aristotle's model, energizing toward a certain telos or end.
It's my contention that, with the structure of ethical energeia in mind, we can do a better job of reading Newman's references to "energy" and "energizing," words he uses frequently, and in ways that reach beyond a simple, modern, post-Newtonian view of "energy."
Some may be asking, "why is this important?" To avoid losing the attention of those few who have gotten this far, I'll save that explanation for Part 2.