According to this source [1] flights departing GVA generated 1.3 million tons of CO2 in 2018. According to this source [2], jet fuel generates 3.16 kg CO2 per kg of fuel. Multiplied by approximate fuel density and we get 2.57 kg CO2 per liter. We can therefore estimate that GVA consumes approximately 500 million (1.3 billion kg CO2/ 2.57 kg CO2 per liter) liters of fuel per year. Jet fuel contains about 35 MJ of energy per liter according to [3] so that's about 17.5 PJ. If the process to convert electricity to jet fuel is 50% efficient, that's 35 PJ. That is equivalent to a 1.1GW reactor running at 100% capacity. At the global average capacity factor of 80%, that's about 1.4GW required. Half a dozen is probably a pretty large overestimate. Alternatively, this would require around 6GW of solar, although 6GW of solar is probably quite a bit cheaper than 1.1 GW of nuclear power.
My back of the envelope calculation is that 1GW for 1 year is 30PJ. Jet fuel has 42MJ/kg with a density of 0.8 kg/L for a total of around 100 million liters of fuel at 100% efficiency. An A321 holds around 30000L which comes out to about 30000 flights equivalent from one reactor. GVA had around 200000 flights in 2018 meaning about 6 1GW reactors equivalent of fuel used (obviously not all flights would be fully loaded but I don't know what a normal load is).
Comparing global fuel consumption with global electricity production is a good approach. It’s clearly substantial, but doable, especially since fuel production can utilize “unreliable” renewables (make gas when the sun shines).
