It's not a significant issue. All renewable energy (solar, wind, hydro, biofuels) comes from the sun anyway and the only difference if that sunpower goes into

It's not a significant issue. All renewable energy (solar, wind, hydro, biofuels) comes from the sun anyway and the only difference if that sunpower goes into 'waste heat' immediately or gets temporarily used for work before turning into the exact same amount of waste heat. Fossil fuels are releasing energy that was taken from the sun millions of years ago, but the direct heat outcome of burning all that is dwarfed by the greenhouse effect of emitted gasses - small changes to how much Earth radiates into space matter much more than the heat produced by burning that fuel. The same applies for nuclear, which does generate extra waste heat but it is not significant compared to the greenhouse effect.