Loved your energy analysis, the chain of thought is what I like. At first 20TWh sounds grossly overestimated, comprising something like an hour’s worth of total recorded world energy consumption, until we realise
the analysis of the input energy has to include the amount of energy required to process whatever fuel was used in the processes of energy supply, and so on, ultimately to the amount of solar energy it took to the create the fuel (millions of years), then we see 20TWh might even be a serious underestimation.
In fact anything consuming any amount of fuel is similarly outrageous when we drill into all of the dependencies.
Of course there is no real method of power generation, it has to ultimately come from the sun, all of it at root source, non of it is renewable, all we can do, apart from plugging directly into the sun by solar farms, is shuffle the energies around, whilst de-creating whatever was created.
I bet we would find interesting direct relationships between the harmful effects of pollutants generated, and the energies shuffled / decreation done, if such a study was ever funded.