Very interesting. The trouble is there is no way he can compete with someone using obsolete XBT mining equipment for space heating, where the effective cost of electricity becomes negative, regardless of the price of electricity.

Making POW useful requires nothing more a than changing the mindset. There are many situations where the heat produced has more value than the electricity consumed. Ever used electricity to produce heat? If the objective is to use electricity to produce heat, then POW mining of crypto currency becomes simply a way to reduce costs.