Thermochemical hydrogen — solar or nuclear — has been studied for a while. The simulation thermodynamic efficiency numbers are excellent (beating electricity ge

Thermochemical hydrogen — solar or nuclear — has been studied for a while. The simulation thermodynamic efficiency numbers are excellent (beating electricity generation by 1.5-2x), but the reaction cycles in practice tend to leak process chemicals or corrode equipment too quickly to be sustainable (even losing, e.g., 0.1% of your iodine per cycle is unacceptable). I believe Japan is considering a reactor made of tantalum. Canada started such a project in 2010 that was supposed to be online by 2016ish but has continued hitting roadblocks.