Though I'm a bit wary of nuclear given there are studies indicating that the heat energy added by thermal power plants contributes surprisingly much to global warming. If we can replace all thermal power plants with renewables that's a nice contribution to reducing global warming. On the order of CO2 emissions from planes if I remember correctly.
I'm sure we could "afford" the heat from thermal power plants if we didn't have so many greenhouse gases. But when we're already so close to the edge of the cliff, every little bit counts.