Can nuclear energy avert the climate crisis?

There is a broad consensus among climate scientists on the climate threat, exceeding 97%. Agreement is lower among the Czech population, at around 75%. This difference probably reflects the public's traditionalist view of life, an unwillingness to change anything, or even to make sacrifices in their lifestyles.

Under the 2015 Paris Agreement, 195 countries worldwide (including the Czech Republic) committed to reducing greenhouse gas emissions to zero, or almost zero, by 2050. We therefore realistically have 25 years left.

One of the main solutions to the climate crisis is assumed to be the need to reduce greenhouse gas emissions, primarily carbon dioxide and methane. The solution lies mainly in low-emission technologies, currently represented by renewable and nuclear energy, systemic changes in transport and agriculture, and, last but not least, the removal of carbon dioxide from the atmosphere.

At the COP28 conference in Dubai, 20 countries called on the global community to triple nuclear electricity generation. The figures in brackets show the share of nuclear energy in 2023. They are France (64.8%), Slovakia (61.3%), Ukraine (55%), Hungary (48.8%), Finland (42.0%), Belgium (41.2%), Bulgaria (40.4%), the Czech Republic (40%), Slovenia (36.8%), South Korea (31.5%), Sweden (28.6%), Romania (18.9%), the US (18.6%), Canada (13.7%), Japan (5.6%), the Netherlands (3.4%), Moldova (0%), Ghana (0%), Mongolia (0%), Morocco (0%) and Poland (0%).

At present (11/24), according to the WNISR, 408 reactors are in operation, covering 9.15% of global electricity consumption. The 20 countries' plan would mean building more than 1,000 (1 GW) reactors (820 new ones and at least 260 more to replace older reactors by 2050).

This would mean beginning construction of at least 70 new nuclear units annually by 2040, as construction time can be assumed to average ten years. Under this scenario, one new project would have to start roughly every fifth day. This number is more than double that seen during the golden age of nuclear expansion in the 1970s and 1980s. It also raises further questions, such as whether sufficient manufacturing capacity exists to build new nuclear power plants and whether there are enough suitable sites for them.

During operation, cooling in the summer months may become a limiting factor at inland locations. During the 2003 heatwave, output at 30 nuclear power plants was reduced or they had to be shut down. A similar situation regularly recurs, and it is almost certain that as the climate catastrophe progresses, the situation will worsen rather than improve.

Nuclear energy's current contribution to the climate is marginal: the existing fleet of nuclear reactors reduces total global GHG emissions by 2–3%, so tripling it would result in a 6–9% reduction in greenhouse gas emissions. Other authors and organisations also challenge the use of nuclear energy as a tool to fight the climate crisis, including Amory Lovins, the Climate Action Network Europe, Allison Macfarlane, former chair of the US Nuclear Regulatory Commission, an article in Deutsche Welle, one in Physic Today, M. V. Ramana's extensive publication Nuclear is Not the Solution, and the major international environmental organisations Friends of Earth and Greenpeace.

Is nuclear electricity generation emission-free?

Nuclear power is not emission-free, as is often claimed in its defence; it is low-emission. Emissions arise during the construction of nuclear facilities, but primarily during uranium mining, enrichment and fuel rod production, and vary considerably according to different authors. Nuclear organisations generally report lower emission values than other authors. It is not easy to determine who is right, but it is likely that professionally nuclear-oriented organisations will, by the nature of their role, favour lower greenhouse gas emission values associated with nuclear electricity generation in order to improve the image of nuclear energy.

The World Nuclear Association, based on IPPC data, states 12 g CO₂ per kWh, which broadly corresponds with an IAEA document stating that CO₂ emissions from the nuclear fuel cycle range from 0.5–4% of emissions from equivalent coal-fired generating capacity. At 820 g CO₂/kWh for coal, this amounts to roughly 4 to 33 g, or an average of 18 g CO₂/kWh.

However, these emission values are not universally shared. According to Jacobson of Stanford University, total emissions from new nuclear power plants range from 78–178 g, averaging 128 g CO₂/kWh. The amount of equivalent emissions associated with nuclear energy over a plant's lifetime was determined based on the studies examined in an article by Benjamin Sovacool, ranging from 1.4 g to 288 g, with an average carbon dioxide equivalent value of 66 g CO₂e/kWh.

This average value is in good agreement with the findings of Manfred Lenzen of the University of Sydney. The study shows that greenhouse gas emissions from light-water and heavy-water reactors range from 10–130 g, averaging 65 g CO₂e/kWh_el. This corresponds to consumption of 0.1 to 0.3 kWh_thermal, averaging around 0.2 kWh_thermal, for every kWh of electricity produced. In their study, Fthenakis and Kim put nuclear energy emissions at 16–55 g, averaging 35.5 CO₂e/kWh.

As uranium concentrations in ore decline, energy consumption for milling and leaching will logically rise, increasing not only the cost of direct extraction but also subsequent environmental damage from greater quantities of leaching chemicals and disposal of residual substances. Specific greenhouse gas emissions will also rise. The average grade currently mined is in the range of 0.5–1 g U/kg of ore. Jan Storm assumes that, with constant nuclear production, the threshold of 0.1 g U per kg of ore will be reached around 2080. If the stated nuclear plans are implemented, this threshold will be reached sooner.

Could fusion (the joining of deuterium and tritium nuclei), as a presumed inexhaustible source of energy, help avert the climate crisis? According to Robert Rosner, former chair of the Science and Security Board of the Bulletinof the Atomic Scientists, practical implementation of this objective by 2050 is entirely unrealistic. Among the problems, he cites above all the availability of tritium and material embrittlement of the walls of the vessel in which fusion would take place.

Estimates of uranium availability

Uranium is not a freely available element, excluding reserves in the world's oceans. Its key deposits are concentrated in a few countries: Canada, Kazakhstan and Namibia, which according to GlobalData's Uranium Mining to 2030 report together produced 70% of the world's uranium in 2023. A further 15% came from Australia and Uzbekistan, meaning that 85% of global uranium came from just five countries. In 2024, mining stood at around 60,000 tonnes , of which around 7,500 tonnes remain after enrichment to an average 4% U235. At annual consumption of 27.6 tonnes of enriched uranium, this would supply 272 reactors with a capacity of 1 GW. A significant part of consumption is therefore covered from stockpiles and dismantled nuclear weapons. According to this publication, expected uranium mining in 2030 is around 75,000 tonnes.

If less profitable ores costing more than USD 130/kg of uranium were also mined, shortages could emerge, in the best-case scenario, around 2050.

Cost comparison of nuclear and renewable energy

Authors at the Fraunhofer Institute, in a research report published this year, put the cost range for nuclear energy from new sources at 13.6 to 49 euro cents/kWh, while for utility-scale photovoltaics with battery backup (3:2) they give a cost of 6.5–11 euro cents/kWh. The average cost of nuclear electricity from new reactors is more than four times higher than that of photovoltaics with batteries. The cost outlook for 2024 for utility-scale photovoltaics should range from 2 to 5 euro cents/kWh.

According to New York bank Lazard, which has financed major global energy groups for decades, the current cost of wind power with storage ranges from USD 42–114, averaging USD 99/MWh, while solar PV with storage ranges from USD 46–102, averaging USD 97/MWh. Nuclear energy from new plants reached double that cost this year, at USD 141–221, averaging USD 181/MWh.

If we compare the research potential devoted to wind and solar sources or battery storage with nuclear research, it is immediately clear that work on renewable and storage technologies is essentially accessible to any technical university or specialist workplace, while there are far fewer such opportunities in the nuclear sector. This difference determines the number of innovations in storage and photovoltaic equipment. Examples of promising, material-efficient storage batteries for grid applications include Dutch Aquabattery, which operates using water and table salt on the principle of a flow battery, and North American FORM ENERGY, which stores energy in iron, the fourth most abundant element in the Earth's crust.

In 2021, 5.8 terawatt-hours of electricity from renewable energy sources were not connected to the grid in Germany, which in combination resulted in millions in losses. The solution is storage capacity.

The limited global support for nuclear energy is also reflected in the volume of investment reported by the International Energy Agency (IEA): USD 771 billion went to renewables last year, USD 452 billion in total to grids and storage, while nuclear received USD 80 billion in investment.

Conclusion

Planning substantial nuclear expansion is a strategic mistake. Nuclear energy is not, and has no potential to become, a key element of decarbonisation. It will divert enormous resources that could otherwise be used for much faster construction of substantially greater renewable energy and storage capacity.

Milan Smrž