I'm greatly enjoying this entire debate, but I'd just like to point out one thing: Elon said he doesn't know for sure how to do it yet or if it's even feasible (although he thinks it is). This means

a) It's possible that not all of the statements he ever made about the Hyperloop will be true for the final design (if any). I'd be especially cautious about the comment about right of way issues. This might as well just mean that he found an unused railroad track or something. And

b) Nobody knows if it can be done. Keep that in mind when debating the ideas. As far as I'm concerned, all ideas are constructive at this point.

I'm not a physicist and it's very likely that this solution is completely impossible, but let me ask anyway. If you just had a 1200 mile long train and you somehow got the mass going in a circle at 1200 mp/h, how much energy would you need to keep that momentum going? Could you cover that with solar panels covering the 1200 miles of track?