I think you can, in theory, break apart stable lead nuclei by spallation, transmuting some of them into somewhat lighter elements (first-row platinum-group elements, tungsten, that kind of thing), which you can fairly easily separate by chemical means, then bombard with neutrons and alpha particles until some of them become gold, go through another chemical separation step, and repeat. You need energy input for all of this, but I don't think you need to deal with significant quantities of antimatter, just the occasional positron emission.

I admit I don't know much about nuclear reactions, so please let me know if I'm talking nonsense here.

I agree that Central European capacity factors for solar are pretty bad, and that heat pumps are still economical in more polar countries, and will remain so for a few more years.

I'll answer the rest of your extremely interesting comment later, as I'm being drawn away at the moment, but I want you to know that I appreciate it very much.