I commented on the blog Social Democracy for the 21st Century: A Post Keynesian Perspective in a post called Hayek’s Natural Rate on Capital Goods, Sraffa and ABCT.
Specifically, the issues in the above blog post are continued in one of my favorite David Glasner posts, Sraffa v. Hayek.
I requote Glasner: "the rate of return from holding all assets net of their storage costs and their current service flows must be equal in equilibrium. If not, you’re not in equilibrium. So all you have to do is find an asset with no storage cost and no current service flow and calculate its expected rate of appreciation and you have the real natural rate of interest."