By P Gosselin
By Frank Bosse
Klimnachrichten here
(Translated, edited by P. Gosselin)
The scientist at the Potsdam Institute for Climate Impact Research (PIK) is an oceanologist and studied physics before his specialist training. He is therefore familiar with thermodynamics and its 2nd law, which states that with every change of state, the “disorder” increases, also known as entropy. This is reflected in warming. Growing entropy is a basic characteristic of our universe; without investing work, everything tends towards disorder .
You are probably familiar with this phenomenon. Growing entropy also prevents perpetual motion machines; every working machine also generates friction and thus heat and inevitably a loss of useful energy. So what does all this have to do with Stefan Rahmstorf?
He published the following post on Twitter (now X) on January 14, 2025:
Screenshot X
[In English: “Nuclear energy, whether from fusion or fission, has the problem of waste heat, just like fossil fuel energy. It is still small compared to CO2, but it will soon become a relevant warming problem with the growing energy demand by mankind.”]
In his tweet, he complains that nuclear energy generates waste heat and would therefore represent a further relevant problem for our planet, which is warming up due to greenhouse gases.
An astute reader will remember that astrophysicist Professor Harald Lesch also advocated precisely this thesis, even in a lecture to teachers(!). He failed as well to take into account that all converted energy (whether from wind, sun or thermal) ultimately leads to an increase in entropy, i.e. to heat. It all depends on the order of magnitude.
If humanity produces energy by burning carbon (which leads to the production of the “greenhouse” gas CO2), the problem is orders of magnitude higher. It reduces the escape of heat by radiation into space and accumulates its effect in the atmosphere, waste heat does not. This has long been known from the scientific literature.
What was the share of low-CO2 electricity of total consumption in Germany in January 2025?
Share of electricity produced in Germany from
solar, wind and hydro power in total consumption
How much of the total consumption was carbon combustion, the “rest” in the chart? Unfortunately, the average for the month was 61%, or just 39% low-carbon electricity. It fluctuated between an outstanding 9% and a completely inadequate 93% if you analyze the hourly data from “Agora Energiewende”.
In Germany, 90 GW of solar power and 69 GW of low-CO2 wind power have been installed; only around half of the total renewable capacity would have been utilized if the “installed capacity” had also been available.
In reality, however, photovoltaics contributed on average only 2% to total consumption, wind 29%, fluctuating widely between 1.7 and 67%. Renewable energies alone are therefore not really suitable for solving the CO2 emissions problem. The weather at around 50° north latitude is too changeable for this. That would be the logical conclusion of “climate enthusiasts” such as Professors Stefan Rahmstorf and Harald Lesch.
And why then completely counter-physical pretexts against the likewise low-CO2 generation of electricity by nuclear power, regardless of the weather? We don’t know. We only know that they are talking nonsense in order to oppose low-CO2 technologies, which were also recommended by the “Climate Council” IPCC, 6th Assessment Report, Working Group III as a necessary supplement for renewable energies.
Doubters of the greenhouse effect are sometimes rightly accused of denying the climate problem. But what are Rahmstorf, Lesch and Co. doing when they reject everything except green energies, which alone are probably only very inadequately capable of solving the climate problem (as shown in January 2025), by swearing about physics?
They are very effectively obstructing the solution to the problem. In the end, it makes little difference to the outcome whether you don’t want to see the challenge or only accept it inadequately with the help of bogus arguments.
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Everybody knows and accepts that CO2 is a greenhouse gas. Everybody knows and accepts that man and his activities emit CO2 to the atmosphere. The other side accepts without proper scientific proof that more CO2 will cause catastrophic global warming. They have no proper science to support their claims. CO2 does help keep the planet from getting too cold at night but CO2 has serious limitations in that regard. CO2 does not act like a blanket rather like a filter merely slowing down the escape of long wave radiation to the upper atmosphere. CO2 does not act linearly rather logarithmically. After a certain point its effects grow smaller. So no we are not wrong to question the trillions of dollars pissed away on things like Net Zero or worthless mandates or building useless wind and solar.
The author is missing the point. Uranium decay generates heat. But it does so regardless of whether the uranium is concentrated in a nuclear power plant or dispersed over the surface of the earth. It is always the same amount of heat. So the claim that we get more heat by concentrating uranium in a nuclear power plant is just plain ridiculous.
The Manhattan Project would like a word.
No, it doesn’t. The Manhattan project is fully aware of the conservation of energy. What we see here is about the timescale of the release of energy, not about the amount of energy.
He does not say that. What he says has nothing to do with “concentrating Uranium in a nuclear power plant”. The Uranium in a plant is already refined to 5% U-235 elsewhere for commercial fuels, 25% for Nuclear subs where stuff has to be smaller, and the operators are more skilled. Fission breaks nuclei and releases their nuclear binding energy, a process completely detached from the conversion of the energy elctromagnetic and particle enrgy released into electrical energy – usually by heating pressurised water to create steam to drive a turbine, using the energy released from nuclear fission, which process is the supposed problem. All very well known.
The level of energy this wastes to the earth’s atmospheric enrgy system is worth about 0.08W/m2 across the whole earth at current energy generation levels (average 20TW). IF we generated 20 times more power generation than now, from nuclear fired boilers, that would create enough waste heat from boilers to match the tiny effect of AGW GHE since 1850, if even real at tat level which assumes all change is due to AGW per the models at 1.6W/m2 (which it demonstrably is not), which perturbation is so strongly fed back by increased losses due to the increase in direct radiation and evaporation/radiation energy loss to space per degree of warming that results (that 2nd Law again) that it is insignificant, GMST wise. IMO Hope that clarifies the point. What you wrote is gobbledegook.
What “climate problem”?
The Earth is not a closed system, so the second law is not so easily applicable. Every increase in temperature leads to a fourth power increase in dissipation into space (Stefan Boltzmann’s law).
This in itself prevents any runaway increase of temperature. The two main GHGs (H2O and CO2) are both saturated, so there’s nothing to expect from that side.
The GHE on the atmosphere is regularly questioned. Not the mechanism itself but its actual effect on temperature. People often dismiss this line of thinking as they believe in the main radiation theory that states an underlying hypothesis about its effect on the atmosphere. But that is about radiation. And there are many anomalies or holes in that argument because it seems to contradict many observed phenomena.One could thus make a quite solid argument that gas laws/ pressure and the combination of H20 in all forms control the effect of incoming radiation without the need of the GHE. Or at least state that the GHE plays an insiqnificant role in the climate system. And before you state the usual arguments FOR the GHE on the atmosphere, i am fully aware of them..but also the many ways it does not explain it..
The professor says, Huh? Even says he is a professor of physics. But hard of sums. I shall visit his X feed and suggest he may be wrong, on the physics.
Why are sums so hard for people? Especially climate “scientists”? This man is Class A gobshite idiot, who cannot do the most basic maths that would support his claims, also known as a “Climate scientist” or “environ mentalist”. All opinions and no science. He has Naomi “no science” Oreskes as a co -author…
Also, as regards comment above… Why say what “you think” to a technical forum about science and engineering when you don’t know and can’t or won’t calculate such a basic thing?
Think before you type, and do the numbers so what you say is not just as wrong? A lot of the posts are about CO2 which this his claim is not. Its trying to say all intense energy generation is bad and cheap plentiful enrgy dependnent civilisation must be ended by imposing weak, intermittent feudal energy sources. For all but the elites.
Do the maths before posting?
You/one may be wrong, but it gives something absolute to test against and get it righter. Don’t believe, do real science, as done outside of climate science and sociology (still get 5/10 for trying and being wrong, because it leads to better understanding).
This is year 11 physics plus some questions of Google (in the UK education system at least). This forum deserves do better. Here is something numerate to check….:
The back of my envelope and the Casio fx-83 says total power incident absorbed by the Earth’s atmosphere and surface is average power per unit area times total area so 240W/m^2 x the (510×10^12) m2 area of Earth.
That gives a Solar energy delivery rate of 122,000TW. CHECK?
The thermal efficiency of a nuclear reactor steam generator is about 1/3. If we generate 20TW in total, as Google says,
that’s 40TW lost as heat. CHECK AGAIN?
So, if it checks out the waste heat from all nuclear generation that is 33% thermally efficient would be 4 parts in 12200.
330PPM 0.04%. 0.08W/m2. Not a lot. CHECK AGAIN
In haste, I may be wrong, E&OE.
Please correct where wrong AND let me know, I filed this for other events when stupid academics environ-mentalist “climate scientists” without physics make it up. Best be right. One more example of clueless academics drivelling from both sides of their mouths?
BTW the Chinese are developing nuclear fission using TRISO pebble bed fuel that is cannot melt down and is cooled by helium gas at 800C. IT works at hight temperature and pressure can use super critical steam generation to drive the turbines, that is, I believe, 50% efficient? Perhaps the experts here will know more? At my level of understanding, it requires water and steam to be raised to a temperature and pressure where the transition become lossless, beyond the critical point.
https://naeye.net/15503/science/triple-point-of-water-the-temperature-where-all-three-phases-coexist/
It’s already used in the most advanced, clean/scrubbed coal fired plants in China, and it is planned to replace the coal boilers with TRISO pebble bed nuclear boilers in some of these plants. Which will reduce all emissions to zero, except the 50% waste heat. Perhaps a serious power engineer /physicist can describe it properly. But you will need to read up on how that happens and why that is a good thing. CEng,CPhys.
JUst visited to point out the error in the physics of his claim. Rahmstorf does not allow replies to his claims, many of which are demonstrably false on the facts and physics he should know.
Nick Stokes is right, for once. But Rahmstorf is still wrong. Not on the thermodynamics, but on the understanding of the consequences.
Stefan, and Nick, are right that nuclear power would yield an addition of heat to our atmosphere through its use. The second law of thermodynamics formulates why this is so, that whatever we do the end state of our energy use is eventually heat.
We as humans cannot affect the total heat released by radioactive decay on this planet. What we can affect is the time it takes for that decay, and thus we can affect the power at whch it happens. But the total heat added is the same.
According to relevant statistics (OurWorldInData, IEA, etc.) the human world produces on the order of 200.000 TWh per year. With 8760 hours available to us this averages at 22.8 TW average power. Keep that in mind.
The main energy source for our planet is our sun. Our planet receives about 340 W /m2 on average throughout the year. This is an average for the entire global surface, 24/7. With 510.100.000 km2 of avilable surface this means our world receives 173.000 TW. All day, every day.
Stefan Rahmstorf is thus worried that our addition of a potential 23 TW will lead to warming. It probably will, that is true. But consider that a change of 0.01% of solar irradiation will do the same. Or a change of -0.01% will negate our potential nuclear addition.
And consider that our ability to measure the solar irradiation at the surface has a +/- 2% uncertainty. Or 200 times the change Stefan is worried about.
Yep, Stefan is right. And it has no consequence whatsoever in the real world.
There is plenty of rationale to conclude that the climate sensifity of CO2 is effectively zero. It is all a matter of science.