Coal produce in average 950 grams of C02 per KW/H and natural gas about 600 grams of C02 per KW/H. Nuclear power require all kind of heavy duty manipulations from extraction of ore to extraction of uranium, which goes through a long list of processes, safety and other products needed, from extracting about 6000 tons of rock to finally have 1 kg of enriched uranium, transported and ready to be used