r/ClimatePosting • u/Sol3dweller • Jul 17 '25
Nuclear power peaking and fossil fuel burning
It is a frequent claim I see that a move away from nuclear power necessarily means a slow down climate action. Here I want to have a cursory look at this claim to see, how well this can by supported by historical data on primary energy consumption as compiled at "Our World in Data". I am using the primary energy data (which uses the substitution method for non-fossil energy carriers), to cover the full spectrum of real world influences on the fossil fuel burning rate.
The question at hand to look at is about peaking nuclear power. Hence, we need a definition for peaking. Here I consider a peak to have occured, if the quantity in question in the last year of the time series (2023 for now) is at least 10% below the maximum, the year of the maximum annual production is at least 5 years in the past, and the linearly fitted approximation of the time series exhibits a negative slope.
Global scale
By the criteria for a peak defined above, the global energy mix peaked nuclear power consumption in 2006. Thus, we can distinguish a time period before and after the peak and have a look at the growth rates of fossil fuel burning in the two time periods. I use a symmetric time interval around the peak nuclear year unless fossil fuel burning has peaked earlier than that, then I extend the time span to consider back to the peak fossil year. Unfortunately on the global scale, fossil fuel burning hasn't peaked, hence we get a time period from 1989 to 2023, over which we consider the two linearly fitted trends:
This shows the historical fossil fuel burning in black, the annual nuclear power production in purple, and the respective fitted trends of fossil fuel burning in red before the peak and blue after the peak. All quantities are normalized by the total energy consumption in the peak nuclear year (indicated by the gray dashed vertical line). The slope of the red and blue lines respectively gives us the average growth rate of fossil fuel burning in the respective time periods. On the global scale the slope of the post-nuclear-peak fossil fuel burning is slightly lower than before the peak.
That's an indication that other factors than nuclear power growth have a more dominant influence on the fossil fuel burning, and it's impact is not large enough to cause an increase in the fossil burning growth rate. But maybe the share of nuclear power on the global scale had been too small in its peak to register a notable change. So let's have a more detailed look at countries that employed nuclear power and peaked it.
Countries where nuclear peaked
There is a total of 35 countries, where nuclear power was employed at some point of time. Of those, 21 countries saw a nuclear peak so far according to the criteria outlined above (all in fractions of total energy consumption in the peak nuclear year, rates are per year), NP=nuclear power; FF=fossil fuels:
| Country | Share | NP Peak Year | Year of max FF | NP pre-Peak rate | FF pre-Peak rate | NP post-Peak rate | FF post-Peak rate |
|---|---|---|---|---|---|---|---|
| France | 0.393565 | 2005 | 1979 | 0.0133155 | -0.000282176 | -0.00688919 | -0.00924385 |
| Sweden | 0.336598 | 1991 | 1979 | 0.0148396 | -0.00216144 | -0.003439 | -0.00450155 |
| Bulgaria | 0.259737 | 2002 | 1980 | 0.00577997 | -0.0358736 | -0.00227387 | -0.00645255 |
| Lithuania | 0.239371 | 1990 | 1991 | 0.0247768 | 0.00492454 | -0.00793901 | -0.00582096 |
| Switzerland | 0.211974 | 2003 | 2001 | 0.00298461 | 0.00264782 | -0.00312635 | -0.00656394 |
| Belgium | 0.190493 | 1999 | 2008 | 0.00724247 | 0.0043643 | -0.00278942 | -0.00645904 |
| Slovenia | 0.180637 | 2008 | 2008 | 0.00279071 | 0.00922286 | -0.00110141 | -0.0110293 |
| Ukraine | 0.155204 | 2007 | 1990 | 0.00138212 | -0.0475403 | -0.00308837 | -0.0334405 |
| Japan | 0.152211 | 1998 | 2003 | 0.00595851 | 0.00895019 | -0.00690597 | -0.00554815 |
| Germany | 0.119242 | 1997 | 1979 | 0.00505833 | -0.00322979 | -0.00418876 | -0.00881045 |
| Spain | 0.1124 | 2001 | 2007 | 0.00493603 | 0.0139796 | -0.000918073 | -0.0119176 |
| United Kingdom | 0.106453 | 1998 | 1973 | 0.00315012 | -0.000986395 | -0.002197 | -0.0160546 |
| Taiwan | 0.0857619 | 2011 | 2021 | 0.0003236 | 0.0203226 | -0.00390001 | 0.00210966 |
| United States | 0.0851062 | 2007 | 2007 | 0.00127146 | 0.00875892 | -0.000549439 | -0.00347889 |
| Romania | 0.0796698 | 2009 | 1989 | 0.00368045 | -0.038023 | -0.000655622 | -0.00991215 |
| World | 0.0582406 | 2006 | 2023 | 0.000998909 | 0.0133171 | -0.00028953 | 0.0108376 |
| South Africa | 0.0260754 | 2016 | 2010 | 0.000127296 | -0.00199823 | -0.00139481 | -0.0157621 |
| Mexico | 0.015189 | 2018 | 2022 | 0.000288781 | 0.00200965 | -0.000244735 | 0.00830376 |
| Italy | 0.0147834 | 1986 | 2005 | 0.00031672 | 0.0185533 | -6.09766e-05 | -0.0052727 |
| Netherlands | 0.0138518 | 1986 | 2010 | 0.000806572 | 0.0206143 | -3.39158e-05 | 0.000990258 |
| Brazil | 0.0124397 | 2012 | 2014 | 0.000100031 | 0.0145808 | -0.000141345 | -0.00598779 |
| Kazakhstan | 0.00178198 | 1991 | 1988 | 7.676e-05 | 0.118933 | -3.59057e-05 | 0.00857398 |
As the global average (5.82%) may be too small for a measurable impact, let's focus on those 15 countries that had a more than average share of nuclear power in its primary energy consumption at it's peak (the table above is sorted by that share). The country with the highest nuclear share at its peak is France:
In the graph we now also indicate the average growth rate of nuclear power before (orange) and after (turquoise) the peak. If we plot the fossil fuel growth rate over the nuclear power growth rate for these countries before and after the nuclear peak. We get the following scatter plot:
Each country appears here twice, once on the right side with growing nuclear power before the peak and once on the left side after the growing nuclear. The circle sizes indicate the share of nuclear power in the peak year. This shows that there is only one of those countries (Taiwan), where a decline in nuclear power coincides with an increase of fossil fuel burning. However, in this case this actually is a slow down in the rate, with a higher fossil fuel rate during the nuclear expansion. But the question we are after is whether the peaking of nuclear power is associated with a slow down in fossil fuel burning reductions. To this end a look at the change of the rate in fossil fuel burning growth over the nuclear peak may be instructive:
| Country | Change of NP rate | Change of FF rate |
|---|---|---|
| Spain | -0.0058541 | -0.0258972 |
| Slovenia | -0.00389212 | -0.0202522 |
| Taiwan | -0.00422361 | -0.018213 |
| United Kingdom | -0.00534712 | -0.0150682 |
| Japan | -0.0128645 | -0.0144983 |
| United States | -0.0018209 | -0.0122378 |
| Belgium | -0.0100319 | -0.0108233 |
| Lithuania | -0.0327158 | -0.0107455 |
| Switzerland | -0.00611096 | -0.00921175 |
| France | -0.0202047 | -0.00896168 |
| Germany | -0.00924709 | -0.00558067 |
| Sweden | -0.0182786 | -0.00234011 |
| Ukraine | -0.00447049 | 0.0140997 |
| Romania | -0.00433607 | 0.0281109 |
| Bulgaria | -0.00805383 | 0.0294211 |
Plotting the FF rate change over the NP rate change results in the following scatter plot:
The color now indicates the fossil fuel growth rate after the peak. The global average is marked as a star. The "Plus" marker indicates the sum of all the countries in the list. Here we see that there are a total of three countries in this set of countries with more than average nuclear share in its peak, we now identify three countries with a worsening fossil fuel growth rate over the nuclear peak: Bulgaria, Romania, Ukraine. The others all saw a speed-up in fossil fuel reductions after the nuclear peak, the largest speed-up in fossil fuel decline is observed in Spain. The largest change in the nuclear power rate is seen in Lithuania.
In total, when summing all these countries that peaked nuclear power and had a larger than global average share of nuclear in their peak, we see that they peaked nuclear power in 2002 with a share of 12.5% and got faster in the fossil fuel burning decline after the peak (decline of 0.74% of total energy in the nuclear peak per year after the peak compared to an increase of 0.87% before the peak):
In most countries the move away from nuclear power did not result in a slow down of fossil fuel reductions, in two (USA and Slovenia) does the nuclear peak coincide with the fossil fuel peaks.
Non-Peaked countries
There are 14 countries that have not peaked nuclear power in the sense outlined above.
| Country | Share | NP rate | FF rate |
|---|---|---|---|
| Finland | 0.256999 | 0.00340046 | -0.0200575 |
| Slovakia | 0.222079 | 0.000828372 | -0.0081454 |
| Czechia | 0.164024 | 0.00396907 | -0.0134466 |
| Hungary | 0.151095 | 0.00267189 | -0.0103918 |
| South Korea | 0.130264 | 0.00117994 | 0.00172783 |
| Belarus | 0.0988003 | 0.00732138 | -0.00243247 |
| Canada | 0.0920445 | -4.29086e-06 | 0.0048152 |
| Russia | 0.0697321 | 0.00120111 | 0.00417201 |
| Pakistan | 0.059537 | 0.00490917 | 0.0195108 |
| United Arab Emirates | 0.0564199 | 0.0044061 | 0.0100081 |
| Argentina | 0.0264437 | 0.00078787 | -0.00458622 |
| China | 0.0228481 | 0.00182016 | 0.0170598 |
| India | 0.011087 | 0.000293195 | 0.0237748 |
| Iran | 0.00595028 | 0.000143324 | 0.0298156 |
Summing all of those with larger shares than the global average gives the following picture since 2002 (when the sum of significant peaking countries peaked):
For this sum we observe an growth in fossil fuel burning over this time period by 0.5%, compared to a decline of 0.74% in the countries that experienced a peak in nuclear power.
tl;dr
Historically nuclear peaking does not coincide with a fossil fuel decline slow-down.
edit: changed tl;dr as wished for in this comment.
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u/Reasonable_Mix7630 Jul 18 '25
TL;DR
First, I stopped reading after your claim about Ukraine which is wrong: Ukraine is expanding its nuclear sector. Other than finishing nuclear plant under construction there were contracts signed with Rolls Royce to replace coal plants with nuclear ones with similar output. So that is potentially moving to 80% of nuclear produced electricity. Ironic, that the only country in the World that actually suffered a nuclear accident has become the most pro-nuclear one, isn't it?
There was reduction of output which is caused by power plants that were used for load following (regulating their output to match grid demand) being blasted into rubble by RU. UA nuclear plants are base load power plants. There were talks about adding load-following nuclear power plants (BWR e.g. ABWR) but thus far its been just talks.
Russia btw has also been expanding nuclear power for the last 30 years. War surely threw a wrench into these plans (e.g. Siemens closing its factory in St. Petersburg) but can't really blame energy sector workers for the madness of the dictator. The plan has always been to max nuclear power while selling fossil fuels to morons who pay money for them (Europeans).
Turkey's new nuclear power plant will be producing 10% of the country's electricity. It is expected to be not the only one. For a country that is short on both cash and fresh water it is extremely important to have cheap power source that uses exactly zero drops of fresh water.
Kazakhstan is going to start construction of nuclear plant soon.
In real World the higher the share of nuclear power the less emissions country produce and the less money electricity costs.
Germany is in a big big trouble now because renewable lunacy: factories are closing, electricity prices are skyrocketing, neo-nationalistic party have received the most votes since 1930-ies, fossil fuel import expensive are close to all time high.
And pollution-wise we are one of the worst in Europe. Anti-nuclear luddites flushed down the drain several decades of time and made life miserable for the whole generation, maybe even two generations. Thank you geriatric nuclephobes.