Meanwhile, fossil fuels are only 'cheap' because the users are pushing the negative externalities off on everyone else in the world. Priced properly they'd be even more costly than they already are.

If 1kg of coal represents 1000 Wh, your generator loses 1/2 to waste heat, you only generate 500 Wh of usable electricity. Some analyses will state that renewable power has to replace the 1000 Wh of embedded energy within the coal, when it only needs to output 500 Wh.

If you use solar panels and generate 500 Wh directly, you have cut your energy use in half, even though the output has remained the same.