It’s not fantasy. I’m working on a startup to enable this technology. It’s a hard problem, but not impossible. And the energy needs are not as great as you think. A relatively small patch of the Sahara or Gobi desert or open ocean would be sufficient.
its indistinguishable from fantasy extrapolating from the given track record . Previous fantasy technology break through like harbor bosch were viable only "after" major diaasters and worldwars and brought with them ever more destructive hidden costs.
But was only usefull with free trade guarantees by a sea empire. In colonial empire times it might aswell have been alchemy to make free cheese on the moon.