Carlton green wrote:It would be a valid point to say that both fossil fuel and nuclear generation contribute to global warming through their steam cycle waste heat, but as far as I know the significant pollution is via burnt fossil fuel emissions - the gas is probably hot as well - and the waste heat effects (heat ‘given’ to rivers and the sea) are of no environmental concern to anyone.
The waste heat output has next to no effect on global temperatures. The pollutants do - because they trap more of the incident solar radiation.
The earth has a diameter of about 6400km, which means it has an area (as seen from the sun) of pi r^2.
That’s 4e13 m^2
Solar incident radiation is ~1.4kW/m^2 at the top of the atmosphere, and about 400W is absorbed/reflected before it hits the ground
That’s 40 Peta watts.
It’s changing the balance of that 40PW radiation balance that has an effect on global temperatures. Because almost energy that passes through a power station ends up as heat in relatively short order anyway. We produce/use somewhere less than 20TW on average, so 5% of 1% of the solar radiation.
A tiny change in that balance will more than dwarf anything else we could possibly do.
However thermal pollution from power plants has long been a significant local issue. Water is less gas soluble as its temperature increases, so local river populations end up starved of oxygen...