Your instincts are excellent: using heat directly is always and everywhere better than turning it into a fungible commodity like electricity, only to convert th

Your instincts are excellent: using heat directly is always and everywhere better than turning it into a fungible commodity like electricity, only to convert that electrical energy to some other form later. (Creating liquid fuel is no different in this regard.) The reality is that there's almost never a practical direct use of the heat at the facility where it is created. It is too low quality for the onsite processes. Economizers and Regenerators are two common pieces of equipment that suck out what heat can be used - what's left is too low temperature for whatever they're making onsite. Sometimes there's an opportunity to broker a deal between two adjacent facilities, where one can use the heat that the other considers waste. But those are rare. Happy to talk about this until you wished you'd never asked. Feel free to email.