Bill forgot the only thing that can truly be a game changer: Nuclear Fusion. In the long run, this is the only solution that can provide the amount of energy required by our modern society.
"ultimately, when heat waves are extreme enough, power plants will need to draw down their power output."[1]
Here [2] is a study which shows anthropogenic heat emissions from energy consumption are a pressure on global climate. If we put out another 200%+ of whatever energy we consume, in the form of thermoelectric cooling (heat) then quite surely that will amount to a bigger problem.
Also, "Thermoelectric power use has a significant impact on water resources and the power sector is highly dependent on these water resources; the United States Geological Survey (USGS) estimated on a national level that 41% OF ALL FRESHWATER WITHDRAWALS in the United States in 2005 were for thermoelectric power operations, primarily for cooling needs (Kenny et al 2009)."[3]
I believe the real game changers are plainly solar and wind. These have shown the most rapid improvements from investment. On similar timescale to developing fission or secure nuclear, floating oceanic wind and solar combined with hydrogen generation rigs (and even ocean plastic filtering) are possible...
[1] https://www.sciencedirect.com/topics/earth-and-planetary-sci...
[2] https://link.springer.com/article/10.1007/s10584-017-2092-z
[3] https://iopscience.iop.org/article/10.1088/1748-9326/7/4/045...
Or used for desalination, hydrogen, syngas, ammonia, methanol, ethanol production [1] etc.
http://www.world-nuclear.org/information-library/non-power-n...
Also, your estimation is incorrect. The thremal rated power of a nuclear reactor doesn't mean it releases 3x as much heat in the environment. At least 1/3 of the thermal energy is converted to electricity, and part of what remains is fed into a new cycle. The overall efficiency of a nuclear reacor is 33-37%. Gen IV reactor projected efficiencies are above 45%.
Its rather rhetorical for us to quibble with my statement "about 3 times.." But in my readings on the matter 33-37% is the theoretic optimal running efficiency of most existing nuclear plants (depends on the kind and expense of turbine cycle and cooling system employed).
In principle you could do the same with nuclear, but there's challenges in siting a reactor close enough to a big city, and also current reactors tend to be too big. SMR's might help, and there's active research in this area.
Generators? Cooling Plant? I don't know about others, but NuScale Power's SMR has natural circulation an passive cooling.
Nuclear fusion would certainly be nice if it could be made to work, but I've lost my enthusiasm about that a long time ago. Solar is giving us far better returns.
You probably mean future society, as this technology is not really viable yet (in its current form).
And the amount of sunlight we receive is enormous. If we could make use of a significant faction of that, it would provide more energy than we ever need. There's no reason that can't do anything that fusion power will ever be able to do on Earth.
The only real advantage fusion power has over solar is that it's independent of the sun and can be used in deep space. Well, once it finally works.