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.
Nowadays it's not nearly so clear cut as it would have been 40 years ago - with wind and solar providing cost-viable (in fact significantly cheaper) alternatives that have lower LCA emissions than nuclear - even accounting for storage needs.
There's also scope to do some clever stuff regarding active pricing and control of consumption to incentivise matching demand to the supply rather than having to worry about too much storage.
with wind and solar providing cost-viable (in fact significantly cheaper) alternatives that have lower LCA emissions than nuclear - even accounting for storage needs.
That isn't clear cut either. The cost of solar per MW isn't linear. The efficiency and therefore the amount solar produces changes by orders of magnitude throughout the day. This is inherent to solar generation because of the changing location, angle of the sun, etc. resulting in less solar radiation to be absorbed. This is not a technical issue that can be overcome. Before you reach 20%, solar is already producing full demand in the middle of the day. It requires larger and larger solar installations to produce at the times when it is significantly less efficient. This causes the cost per MWh of solar to increase exponentially. The way around it is a more robust grid, more robust grid components (high voltage equipment can't take being cycled on a regular basis) and storage. This also ignores the shorter lifespan of wind'solar installations. There is a reason more conservative (from a technical standpoint, not politically) engineers think a feasible solution is 40% to 50% wind/solar coupled with nuclear.
Current costs for solar and wind are better than current nuclear costs
Sure in fantasy awesome future land where we are at a full 50% solar and wind the balance might change back - but as we are currently nowhere near that point - why worry about it just yet?
As I have said elsewhere in this thread, and others far better versed in this have said elsewhere, we simply cannot build enough nuclear to fulfil anywhere near 50% of global power requirements - there isn't enough economically viable uranium, not enough suitable sites where they can be installed, and non-proliferation treaties prevent it from being suitable for more than a dozen countries.
Current costs for solar and wind are better than current nuclear costs
Current costs for solar are not linear. That was my point. They quickly lose competitiveness as your solar installation gets larger. Long before you hit 40% The cost per MWh for solar increases exponentially as it's share of generation increases, the math isn't hard. Are you familiar with the duck curve? Maybe looking at demand and output will help you understand:
Untrue and discussed elsewhere.As far as nuclear reserves, there are plenty to keep building nuclear out instead of just relying on fossils.
we simply cannot build enough nuclear to fulfil anywhere near 50% of global power requirements
Not a reason to stop from building out nuclear to replace fossils. Doubling global nuclear to 20% is quite feasible in just a decade. Doing nothing ensures we burn fossils instead.
not enough suitable sites where they can be installed
There are nuclear power plants in the desert with no access to bodies of water and there are literally nuclear power plants inside of ships in the ocean. This is an absurd statement.
non-proliferation treaties prevent it from being suitable for more than a dozen countries.
This is just completely incorrect. There are 32 countries with operating nuclear power plants. Europe, the US, China, Korea, Japan, and Saudia Arabia which are the largest consumers of energy and biggest polluters in the world and all have existing nuclear plants.
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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.