The efficiency of converting random energy into useful energy (either mechanical or electrical) has always plagued engineering.
For computer systems your usually so concerned with getting the heat away, that your not even worried about energy capture. But if you had a large enough system you could make something, but probably not worth the effort for the complexity introduced.
Yeah Linus tech tios has made numerous videos about heating rooms or pools with stuff in his server racks. I think with a lot of heat produced like that the added compelxity is worthwhile especially if the person is somewhat knowledgeable, heck, I see more people going the server rack way more now that self hosting and other open source things are becoming a little more common, at least as far as online people goes.
