Possible, but using the heat directly for industrial or heating purposes is probably the best bet - it's just awkward cause transporting heat over large distanc

Possible, but using the heat directly for industrial or heating purposes is probably the best bet - it's just awkward cause transporting heat over large distances is significantly more expensive than electricity, which is usually why you want some sort of co-generation. Ultimately, you don't even need thermocouples, you just need more heat engines with ever decreasing working fluid temperatures, and then it all comes down to your capital costs.