So of course that is why they need government funding - because it is such a good idea, and there are no sources of capital in the USA for capital other than the government.
The question is NOT technical feasability. Loans are made for economic reasons.
This is government subsidized loans in a market with government subsidized consumption.
You’re right... if it’s that good, the private sector would fund it... EXCEPT if a private sector firm loaned the money, the environmentalists would do everything they could to stop the project in courts and legislatures. Sigh. Solar towers do work and can provide baseline power!