While CO₂ is not produced directly when producing electricity from nuclear power, it is obvious that obtaining the radioactive material and preparing it for its use in a plant inevitably produces some CO₂. Thus, the claim that nuclear power is CO₂ free is demonstrably false when extended to the entire process chain.

This, of course, can also be said about any other form of power plant: The mining of coal itself produces CO₂, obtaining the raw materials and manufacturing solar cells does it too, etc.

The question is:

Is nuclear power cleaner than other means of power with respect to total CO₂ output for the entire process?

  • 3
    Does anyone claim otherwise?
    – Sklivvz
    Apr 5, 2011 at 23:35
  • It was used by some politicians in Germany. Trying to dig out the claim... Okay. It was Kurt Beck, Prime Minister of the German state of Rheinland-Pfalz, of the Social Democrats. Now trying to find an English citation of this.
    – Lagerbaer
    Apr 5, 2011 at 23:36
  • 2
    There is one thing that bugs me - generally when comparing nuclear vs fossil there is one basic assumption that you need to specify: are we talking about nuclear in a nuclear energy economy or nuclear in a fossil fuel economy? All the papers I've read do specify what assumption they apply to. Please edit your question to reflect this (do not answer in the comments).
    – Sklivvz
    Apr 6, 2011 at 5:30
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    @andrew grimm: I'm not aware of any mining trucks that don't. The electric trucks I've heard about are diesel-electric in the same way that (say) trains are. This is typical: hitachi-c-m.com/global/company/csr/environment/research/…
    – Мסž
    Apr 6, 2011 at 6:06
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    @SklivvzL can you give an example of a nuclear energy economy? Otherwise you'd be comparing a theoretically possible thing with a real thing, with a lot of assumptions required for the theory.
    – Мסž
    Apr 7, 2011 at 0:48

2 Answers 2


Low range estimate: 1.4 g CO2 equivalent per kilowatt hr

Mean estimate: 66 g CO2 equivalent per kWh

High range estimate: 288 g CO2 equivalent per kWh

This is from a metastudy of 103 studies

You can access the full text from this page on the Nuclear Information and Resource Service

Here is a link to the PDF: Sovacool, B. K. 2008. Valuing the greenhouse gas emissions from nuclear power: A critical survey. Energy Policy v. 36 (8): 2950-2963.

For comparison, a natural gas-fired power plant might emit 515.29 g CO2 per kWh (per wikipedia: http://en.wikipedia.org/wiki/Fossil_fuel_power_station#Carbon_dioxide; (conversion to metric mine & therefore mistakes are as well.) Coal and Oil-fired plants will emit more CO2 than a natural gas plant.

ETA: After more thorough checking, confirmed the neighborhood for CO2 equivalents emitted throughout the life cycle for natural gas and coal plants from Jarmillo et al. "Comparative Life-Cycle Air Emissions of Coal, Domestic Natural Gas, LNG, and SNG for Electricity Generation" in Environmental Science and Technology from 2007, link: http://www.ce.cmu.edu/~gdrg/readings/2007/09/13/Jaramillo_ComparativeLCACoalNG.pdf Natural Gas midpoint: 499 g CO2 equivalent per kWh Coal midpoint: 953 g CO2 equivalent per kWh These are close enough to the wikipedia figures (although not exactly the same) that it appears wiki is also using the lifecycle emissions. Again, the conversion to metric is mine & etc.

A lot of science and policy work treats nuclear power as having 0 CO2 emissions, but that's not quite true, and especially is less true if the higher emissions numbers are more correct.

  • 4
    Considering nuclear power to have 0 emissions is the same logic as employed by the environmental movement to claim that wind and solar have 0 emissions. Both omit any emissions not produced directly by the generation process. My father (when working in dairy decades ago) once had a comprehensive study done about the environmental impact of paper cartons and glass bottles. Turned out that when taking the impact of production and cleaning into effect, cartons actually have a lower impact.
    – jwenting
    Apr 27, 2011 at 6:48
  • 2
    Actually I was talking about certain outputs from the nuclear power industry, not the environmental movement: "Officials in the nuclear power industry say references to carbon-free energy in their promotions refer only to the power-plant operation – and are not intended to describe carbon emissions during the entire nuclear life cycle." From the ( csmonitor.com/2007/0307/p01s04-sten.html ) Christian Science Monitor. Really, neither the environmental movement nor the nuclear power industry are monolithic, so it's not valuable to treat them as if they hold a unified opinion. Apr 27, 2011 at 13:02
  • 1
    yes, I was merely explaining how those come about. If you compare the direct output only, there's no output from a nuclear powerstation or a wind turbine. If you count the entire production cycles, such output exists in both cases.
    – jwenting
    Apr 27, 2011 at 13:46
  • 2
    It's not clear from what is written here whether the figures for the gas, coal etc. plants includes all the other factors involved in giving nuclear plants a non-zero CO2 emission figures. I would expect more CO2 to be generated in transporting, mining and refining coal and gas ready for their combustion. Apr 27, 2011 at 15:39
  • Thanks. I've added clarification to natural gas and coal numbers with a second source that I know is using lifecycle numbers comparable to nuclear. Apr 27, 2011 at 17:13

Answer: Yes, lower than combustion based sources like coal, oil, and gas. Not lower than renewable sources like solar and hydro.

National Renewable Energy Laboratory performed a similar study to that posted by @FlyingSquidwithGoggles. This might be a less biased source (NIRS page header says "Nuclear Power: No Solution to Climate Change" and contains much anti-nuke literature).

After screening articles by their criteria, they ended up with ~300 article inputs to the data, and ~1000 data points total.

Here are some of the figures listed by source: (Min, Median, Max)(in g CO2/kWh).

  • Hydro: 0, 4, 43
  • Solar: 5-7, 22-46, 89-217
  • Nuclear: 1, 16, 220
  • Nat Gas: 290, 469, 930
  • Coal: 675, 1001, 1689

Source: "Special Report on Renewable Energy Sources and Climate Change Mitigation of the Intergovernmental Panel on Climate Change",

  • 1
    How is nuclear more than solar? Because of the 217 and the 220 maximums?
    – Jose Luis
    Jun 19, 2015 at 14:11
  • 2
    Yea I think thats why I used this ordering. Also, I'm trying really hard to be unbiased, since I am a reactor engineer at a nuclear power plant.
    – usncahill
    Jun 19, 2015 at 16:43
  • 1
    I think it would be extremely useful to have the ranges of the maximum for nuclear as solar has it. Like 100-220 or I don't know. In any case Solar and Nuclear are pretty much tied IMHO (Nuclear seems even less)
    – Jose Luis
    Jun 20, 2015 at 16:52
  • 1
    Ordering by maximum seems kind of useless IMO. It basically only tells you how many plants are horribly outdated, or poorly situated. You'd only see it drop as these facilities are decomissioned, which doesn't depend on their CO2 cost at all. For current state, median seems the most telling; for what's the best investment for future plants, neither of the numbers is too useful (max in solar may include places that really aren't good areas for solar power generation, for example, while min may only be available in very limited conditions).
    – Luaan
    Apr 26, 2017 at 9:11
  • 1
    Regardless, the list ends up in a similar order, with fossil plants being significantly higher by all measures. The reader can place these in whatever order they desire. Surprised that there are 4 comments regarding data ordering, and 0 regarding implications, how the chosen answer doesn't answer the question, etc.
    – usncahill
    May 3, 2017 at 16:35

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