The latest figures on global carbon dioxide emissions call into question the world’s efforts to tackle the climate crisis. CO2 emissions are set to soar 4.9% in 2021, compared with the previous year, according to a study published earlier this month by the Global Carbon Project (GCP), a group of scientists that track emissions.
In 2020, emissions dropped 5.4% due to the COVID-19 pandemic and associated lockdowns. Most observers expected a rebound this year — but not to such an extent. The energy sector continues to be the largest emitter of greenhouse gases, with a share of 40% — and rising.
But what about nuclear? Supporters of the controversial energy source say it’s a climate-friendly way to generate electricity. At the very least, it’s something we could use until we’re able to develop comprehensive alternatives. In recent weeks, particularly during the COP26 climate summit, advocates have been creating a stir online with statements like “if you’re against nuclear energy, you’re against climate protection” and “nuclear energy is about to make a comeback.” But is there anything to it?
Is nuclear power a zero-emissions energy source?
No. Nuclear energy is also responsible for greenhouse gas emissions. In fact, no energy source is completely free of emissions, but more on that later.
When it comes to nuclear, uranium extraction, transport and processing produces emissions. The long and complex construction process of nuclear power plants also releases CO2, as does the demolition of decommissioned sites. And, last but not least, nuclear waste also has to be transported and stored under strict conditions — here, too, emissions must be taken into account.
And yet, interest groups claim nuclear energy is emission-free. Among them is Austrian consulting firm ENCO. In late 2020, it released a study prepared for the Dutch Ministry of Economic Affairs and Climate Policy that looked favorably at the possible future role of nuclear in the Netherlands.
“The main factors for its choice were reliability and security of supply, with no CO2 emission,” it read. ENCO was founded by experts from the International Atomic Energy Agency, and it regularly works with stakeholders in the nuclear sector, so it’s not entirely free of vested interests.
At COP26, environmental initiative Scientists for Future (S4F) presented a paper on nuclear energy and the climate. The group came to a very different conclusion. “Taking into account the current overall energy system, nuclear energy is by no means CO2 neutral,” they said.
Ben Wealer of the Technical University of Berlin, one of the report’s authors, told DW that proponents of nuclear energy “fail to take into account many factors,” including those sources of emissions outlined above. All the studies reviewed by DW said the same thing: Nuclear power is not emissions-free.

How much CO2 does nuclear power produce?
Results vary significantly, depending on whether we only consider the process of electricity generation, or take into account the entire life cycle of a nuclear power plant. A report released in 2014 by the UN’s Intergovernmental Panel on Climate Change (IPCC), for example, estimated a range of 3.7 to 110 grams of CO2 equivalent per kilowatt-hour (kWh).
It’s long been assumed that nuclear plants generate an average of 66 grams of CO2/kWh — though Wealer believes the actual figure is much higher. New power plants, for example, generate more CO2 during construction than those built in previous decades, due to stricter safety regulations.
Studies that include the entire life cycle of nuclear power plants, from uranium extraction to nuclear waste storage, are rare, with some researchers pointing out that data is still lacking. In one life cycle study, the Netherlands-based World Information Service on Energy (WISE) calculated that nuclear plants produce 117 grams of CO2 emissions per kilowatt-hour. It should be noted, however, that WISE is an anti-nuclear group, so is not entirely unbiased.
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