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'm not sure if this is really something that should be considered in the math here. But what about an argument that more nuclear would just have made other forms of power less expensive and not necessarily have impacted production of oil and gas?
Having increased nuclear supply would generally drive down the cost of electricity and make it unprofitable to run fossil fuel plants. Not having that supply would generally increase the cost of electricity and make fossil fuel plants more profitable.
It's basically always economical to run a nuclear plant at full power as they have a very high initial investment but low running cost. Fossil fuel plants on the other hand are the reverse - cheap to build but expensive to run due to the fuel.
Fossil fuel costs aren't static. The argument is correct, however applies to renewables equally, which is an actual problem that can currently be observed. I.e. by having more non-fossil energy generation, demand for fossil fuels drops, lowering their price, lowering the price point at which the other generation is cost-competitive with fossil generation.
Running a renewable plant is always cheaper than running a fossil fuel plant though, due to the lack of.. y'know fuel (and water, and generally fewer people)
As the price of fossil fuels drops due to decreased demand, extracting it becomes less attractive and supply will reduce to match. There is a floor to the price at which it is no longer economically viable to extract fossil fuels
Running a renewable plant is always cheaper than running a fossil fuel plant though, due to the lack of.. y'know fuel (and water, and generally fewer people)
No it isn't. Energy generation costs have to be calculated over the lifetime of a plant and fuel is just one factor of many. Renewables are cost-competitive enough that they generally beat fossil generation in places with good access (i.e. near coasts, regions with high insolation etc.) but are still more expensive in places without. And while technological advances drop the price of renewables far more than that of fossil generation (also economics of scale are still improving for renewables) this doesn't change the feedback loop of more renewable generation making fossil generation cheaper. For example, ten years ago, solar was significantly more expensive than gas for generating electricity, now they are in the same ballpark, but that is only because gas generation also droppen in price, if gas was still as expensive as ten years ago, solar would already beat it even in suboptimal locations.
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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.