If you have the time you could engineer a device that operates physical switches to represent bits, sort of like a curta calculator. Make it with enough bits available and engineer in an x86 compatible instruction set and hot damn you've got an electricity free computer, which (if you have the time) you can then manually set the storage bits into positions representative of your Linux filesystem with a minimal install. Figure out how you bootstrap the startup, perhaps engineer correct starting positions for the active bits (memory) such that you have an initramfs.

Can be done, technically you could do it with windows too I guess but boo close source software

i've seen 2 such examples: one on solar and another using piezoelectrics along with the wind