One major category of such processes is calcination, both for cement (CaCO3 >> CaO) and alumina (Al(OH)3 >> Al2O3). This can be done with concentrated solar hea

One major category of such processes is calcination, both for cement (CaCO3 >> CaO) and alumina (Al(OH)3 >> Al2O3). This can be done with concentrated solar heating: https://pubs.rsc.org/en/content/articlehtml/2017/gc/c7gc00585g https://pubs.rsc.org/en/content/articlehtml/2017/gc/c7gc0058... https://www.sciencedirect.com/science/article/pii/S0038092X18307874 https://www.sciencedirect.com/science/article/pii/S0038092X1... But building enough plants to actually do this at scale could take a while. Supposedly there was an anode developed for electrolytic iron reduction: https://www.nature.com/articles/nature12134 https://www.nature.com/articles/nature12134 but there have been problems with scaling it: https://news.ycombinator.com/item?id=30349905 https://news.ycombinator.com/item?id=30349905 Between calcination, smelting and heating, you've addressed a pretty big chunk of fuel-burning processes. The question is whether we can get these kinds of technologies online in time without Manhattan-Project levels of government support, since that does not seem to be forthcoming.