If I see one more model of secular stagnation and negative equilibrium real interest rates, that does not include land....I'm going to throw a real wobbly.
What is it with you townies? Have you never looked out of the window, when you fly (do you ever drive?) from one city to another, and wondered about all that stuff you see out there? It's called "land". It grows food, that you eat. And that land is valuable stuff, and there's a lot of it, and it can last a very long time, and it pays rent (or owner-equivalent rent). And if the rent on that land is strictly positive (which it is), and if the price of that land is finite (which it is), then the rate of interest you get by dividing that annual rent on land by the price of land is going to be strictly positive. And that's a real rate of interest, because land is real stuff, and what it produces is real stuff too.