The United Nations’ Intergovernmental Panel on Climate Change issued a special report in 2012, Renewable Energy Sources and Climate Change Mitigation. The graph on page 19 shows that nuclear’s calculated lifecycle emissions are comparable to other non-emitting renewables.
The World Nuclear Association (PDF) published a study in 2011 that compiled and analyzed 21 different life-cycle emissions studies and made the following observations:
Greenhouse gas emissions of nuclear power plants are among the lowest of any electricity generation method and on a lifecycle basis are comparable to wind, hydroelectric and biomass.
Lifecycle emissions of natural gas are 15 times greater than nuclear.
Lifecycle emissions of coal generation are 30 times greater than nuclear.
The International Atomic Energy Agency in 2007 released a report titled: Guide to Life-Cycle Greenhouse Gas (GHG) Emissions from Electric Supply Technologies (PDF). The report states the following about nuclear:
"From a GHG emission perspective, nuclear power plants (i.e. LWR) are very attractive since they have a huge GHG life-cycle reduction potential when displacing fossil fuel fired power plants, as well as the ability to provide energy services similar to most fossil fuel based energy technologies. … [O]n average LWRs have the second lowest life-cycle GHG emissions of all assessed technologies."
In May 2005, British Energy completed a study (PDF) into the life-cycle impacts of generation from its Torness nuclear power station. The assessment covered the entire fuel cycle and included nuclear waste, spent fuel, CO2, SO2 and NOx emissions. The total emissions of CO2 from electricity generated at the Torness power station, calculated on a life-cycle basis, are estimated to be just over 5 grams/kWh. This compares to emissions of CO2 from a typical UK coal plant of around 900 grams/kWh, based on the operational stage alone. Typical gas power station CO2 emissions are around 400 grams/kWh.
A University of Wisconsin study (PDF) in 2002 found that nuclear energy’s life-cycle emissions are 17 metric tons of carbon dioxide-equivalent per gigawatt-hour. Only wind and geothermal sources ranked lower, at 14 and 15 metric tons of carbon dioxide-equivalent per gigawatt-hour, respectively.
An International Energy Agency analysis (PDF) in 2000 found that nuclear power’s life-cycle emissions range from 2 to 59 grams of carbon dioxide-equivalent per kilowatt-hour. Only hydropower’s range ranked lower, at 2 to 48 grams of carbon dioxide-equivalent per kilowatt-hour. Nuclear energy’s life-cycle greenhouse gas emissions are lower than wind (7 to 124 grams of carbon dioxide-equivalent) and solar photovoltaic (13 to 731 grams of carbon dioxide-equivalent), according to the agency’s analysis. The life-cycle emissions from natural gas-fired plants ranged from 389 to 511 grams of carbon dioxide-equivalent per kilowatt-hour.
False Claims of Nuclear Energy’s Life-cycle Emissions
Many nuclear critics have repeated a false claim that nuclear plants will soon need to use lower-grade uranium ore, which requires more energy to extract, and would therefore raise nuclear’s life-cycle emissions profile. The false claim originated in a paper by Jan Willem Storm van Leeuwen and Philip Smith.
Several scholars and organizations have debunked their claims. The University of Sydney, in Australia, published the most comprehensive critique. The 2006 report, Life-Cycle Energy Balance and Greenhouse Gas Emissions of Nuclear Energy in Australia (PDF), discussed the main areas of disagreement with the Storm van Leeuwen and Smith argument. A table outlining many discrepancies in Storm van Leeuwen and Smith’s assumptions appears on page 65 of the university’s report.
British Energy conducted a follow-up study to its study on the Torness station that showed even with a very low-grade uranium ore, CO2 emissions would remain very small. If Torness used this ore for all of its fuel, its emissions would rise from 5.05 g/kWh to 6.85 g/kWh.