Make money writing when you sell your essays over an over again
Written an essay? Sell it. And don’t stop there. As I point out in this article, you sell first serial rights, and maybe some (limited) electronic rights. You can sell an essay many times: just explain where it was published previously.
And of course, once you’ve sold each essay, and are convinced that there aren’t any more markets for it, you can compile your essays into an ebook (and book), and self publish them.