Excellent post on an important topic. I apologize for being a little late to the party.
When it comes to energy density as measured by watts per square meter of land use, you did a good job of pointing out both current figures and the asymptotes for many renewable sources. Have you thought much about the theoretical limits associated with nuclear fission technology?
Here is some food for thought for you and others in this discussion. The B&W mPower(TM) reactor is designed to produce 360 MWe and to be sited on a 40 acre site. That works out to roughly 2,200 watts/square meter.
That kind of power plant may someday be located within densely populated cities, reducing the need for land to be devoted to transmission lines. As a submariner who has coexisted inside a sealed ship with a reactor all ways less than 200 feet away, I am comfortable with having mPower type reactors as next door neighbors.
There are many other fission power systems that can achieve this kind of power density. They are safe and emission free. I used mPower numbers because I happen to have them at my fingertips.
Rod Adams, Publisher, Atomic Insights
Disclosure: My comments on the web are strictly my own views and do not necessarily reflect those of my employer. However, I am employed by B&W on the mPower reactor development team, so I suppose I have an inherent bias. I am proud of the technology we are refining.