Solar thermal is an alternative to PV. Some greens are touting the advantages of solar thermal especially energy storage. I am not sure if solar thermal can scale as its advocates insist. Solar thermal technologies have been around for a long time but the technology is receiving renewed investor interest in the last few years. Perhaps someone with more expertise can comment on the economic viability of solar thermal as compared to PV for power generation.
Tower-based solar thermal with huge underground thermal storage reservoirs to level load a secondary working-fluid system for actual power generation makes a lot of sense for electric generation.
Locate it in vast areas of the desert southwest, and couple it with a new advanced high voltage direct current backbone across the continent to move the electricity across the country and into the existing AC grids.
Call it a 20 year project and this is a workable technology.
I am in the oil industry, and the only long-term substitutes for liquid hydrocarbons (most likely bio-engineered algaes) will take time also to come into place.
Fortunately there are actually huge amounts of oil and natural gas still in place, and accessible at rational prices that the economy can afford. Land and offshore drilling technology has been developed to the point that aversion to drilling has no truly substantive / fact-based underpinnings or justification. It is all emotion/”taste” driven (nimby bs). These are still factors - not adult ones, but childish ones.
So we have time for a 30-50 year transition for much electric generation and alternative liquid fuel technology to be developed.
Then we are talking about energy sufficient for a robust economy virtually without limits - plenty to get us to the next unstoppable nature-driven ice-age, Yellowstone-caldera eruption, or NEO asteroid or Oort-cloud comet impact - when all bets are then off.
Maybe we can get a colony with long-term viability on Mars before then, as a back-up plan.