This could be flipped - I.e. using a Japanese domestic fuel cell[1] one could install a hot water heater in the home, and get 'free' electricity to run a server

This could be flipped - I.e. using a Japanese domestic fuel cell[1] one could install a hot water heater in the home, and get 'free' electricity to run a server, that could possibly do something productive to offset the associated capital and operational expenditures. [1] https://www.j-lpgas.gr.jp/en/appliances/ https://www.j-lpgas.gr.jp/en/appliances/ (Interesting aside: some people in Japan combine these with a solar/battery array to achieve robust all-season off grid self sufficiency, without combustion, which I think is quite neat!)