Hacker News Reader

Comment by paul | Hacker News Reader

Show your math. Unless those nukes are very small, your claim seems way off.

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.

I forgot to add the sources earlier. Here they are now: [1]: https://rapports.gva.ch/rdd/2019/en/Article/minimiser-l-empr... [2]: https://www.eesi.org/papers/view/fact-sheet-the-growth-in-gr.... [3]: https://en.m.wikipedia.org/wiki/Energy_density

agreed, 1.1 GW seems reasonable for GVA. thanks!

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).

Another quick calculation, in addition to the one from tfussell:

Google tells me [0] that total fuel consumption by commercial airlines in 2019 was 95 billion gallons. One gallon of fuel has around 33 kWh of energy.

Power capacity needed to produce that amount of energy in a year is around 358 GW.

Total world electricity production in 2020 was around 3000 GW-year [1].

[0] https://www.google.com/search?q=total+yearly+aircraft+fuel+u...

[1] https://www.google.com/search?q=total+world+electricity+prod...

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).

I agree it was overestimated, note to self: always redo ppl's maths.

1) number of barrels of jet fuel per day in switzerland:

34000 barrel / day = 0.39 barrel / s

https://www.indexmundi.com/energy/?product=jet-fuel&graph=co...

2) energy in a barrel of jet fuel:

1700 kWh / barrel = 6120000000 J / barrel

3) total power for switzerland:

2.4 GW

so more like 2-4 reactors for all switzerland.

Reply on news.ycombinator.com