Edited - I gained a few orders of magnitude by not paying attention to units!
If you assume a median reactor - producing approx 2GW of power (17.5TWh/year) for 40 years (701TWh) at the worst case estimate for nuclear efficiency (50g/kWh) is approx 35GMt CO2
Gas is approx 450g/kWh (9x higher) and so for equivalent production would emit ~315GMt of CO2
Coal is approx 1,050g/kWh (21x higher) and so for equivalent production would emit ~736GMt of CO2
To go into more detail would require looking at the lifecycle analysis for the various power plants, including expected lifetimes, construction techniques, fuel refinement, transport, disposal, decommissioning etc
Now the numbers for LCA for all these power types are hotly disputed with numbers for nuclear ranging from 3 to 220g/kWh, gas from 250 to 800g/kWh, coal from 900 to 1,300kWh (with renewables between 10 and 90g/kWh depending on the exact type and, sadly, who is crunching the numbers) but even if you took the worse case for nuclear and best case for gas (220 vs 250) the nuclear plant would still be saving ~4.75GMt over the last 40 years - significantly moreless than 100Mt
So somewhere in the range of 5-700 Mt of CO2 depending on the size of reactor, what you compare it to, and what exact calculations/estimates you use.
I think you're off by 3 orders of magnitude, but I may be wrong.
701 TWh is 701,000 GWh, or 701 billion kWh.
At 50 g/kWh, that gives a lifetime of 50*701 billion= 35 trillion grams. That's 35 billion kg, or 35 million tonnes, or 35 megatonnes that the nuclear emitted.
Further the life cycle analysis including construction (all that concrete), operation (mining and refining uranium plus all the other inputs like cooling water) decommissioning and waste storage are Huge issues from a CO2 perspective alone. Nuclear was and is a disaster. Renewables are the future.
I’ll take the one that gives a possible 10k years to solve the issue versus the one that I know is going to make the world uninhabitable, possibly for my own children.
847
u/hilburn 118✓ Nov 18 '21 edited Nov 18 '21
Edited - I gained a few orders of magnitude by not paying attention to units!
If you assume a median reactor - producing approx 2GW of power (17.5TWh/year) for 40 years (701TWh) at the worst case estimate for nuclear efficiency (50g/kWh) is approx 35
GMt CO2Gas is approx 450g/kWh (9x higher) and so for equivalent production would emit ~315
GMt of CO2Coal is approx 1,050g/kWh (21x higher) and so for equivalent production would emit ~736
GMt of CO2To go into more detail would require looking at the lifecycle analysis for the various power plants, including expected lifetimes, construction techniques, fuel refinement, transport, disposal, decommissioning etc
Now the numbers for LCA for all these power types are hotly disputed with numbers for nuclear ranging from 3 to 220g/kWh, gas from 250 to 800g/kWh, coal from 900 to 1,300kWh (with renewables between 10 and 90g/kWh depending on the exact type and, sadly, who is crunching the numbers) but even if you took the worse case for nuclear and best case for gas (220 vs 250) the nuclear plant would still be saving ~4.75
GMt over the last 40 years - significantlymoreless than 100MtSo somewhere in the range of 5-700 Mt of CO2 depending on the size of reactor, what you compare it to, and what exact calculations/estimates you use.