Noting this article on Next Big Future reminded me about the Kardashev Scale, and reading up on it again can certainly be a stimulus for the imagination.
The Polity, I suspect, is merely a Type I civilization, perhaps sliding into Type II territory with the construction of a Dyson sphere. The Heliothane, of Cowl, are also edging into Type II territory with New London sitting over the sun and tapping energy from it. Go check out the links to get your mind blown … so to speak.
The picture here is one from Halo, which seems to have some seriously cool artwork.