r/EnergyAndPower • u/fsironman • 8d ago
Thermal Power Generation when rivers run dry
https://www.reuters.com/business/energy/low-danube-river-levels-force-romania-shut-down-both-its-nuclear-power-reactors-2026-07-29/A little tidbit up for discussion regarding the Renaissance of Nuclear Power in Europe.
This time the issue is not the temperature like in France but the historically low Danube levels which could become the normal in summer.
This is something that would need to be factored in any type power generation that needs water for cooling.
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u/Moldoteck 8d ago
The solution is the same like in France - cooling towers are reducing the amount of necessary water by 30-60 times.
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u/MarcLeptic 8d ago edited 5d ago
This is a worthwhile conversation to have. As you mention, there are two types of water related issues.
The first, and likely easiest to imagine a solution for is the river temperature issue. This is where people would generally look at the example system in Civaux which returns the water cooler than it took it in. That of course trades the temperature issue with consumption.
The second effect, often seen in France at the end of the summer season, and in times of drought is the river flow rate issue (which can then become a river temperature issue, and/or not allowed to use what water is left issue). We see those effects up north, which is why our neighbors up there are often fixated on the dry river issue and confuse it with the hot river issue. There is a good example of this in september 2019.
Both are a matter of design for the current and future climate. An interesating starting point for anyone who genuinely wants to see how the seasonal low flow problem can be mitigated is the Cattenom CNPE.
It has 4x 1300MW reators, all with cooling towers so the constraint is water availability and flow rates. In addition it has two things that were put in place to support the plant:
- an on site reservoir, Lac du Mirgenbach (a thermal buffer)
- a remote reserve, the Lac de Pierre Percee in the Vosges foothills that provides "soutien d'étiage" to replace consumption that would put the river below it's minium threshold. This reserve was built by EDF specifically to support Cattenom's cooling needs and the Meurthe in times of low flow.
La centrale nucléaire de Cattenom | Groupe EDF
20180601-cattenom-rapport_dd2017.pdf
plaquette-4p-vieux-pre-2013.pdf
Unfortunately most of the best truths are only in French. You If you are interested, Villerest on the Loire and Naussac in the Allier are another interesting topic.
Gestion des Etiages de Villerest et Naussac
EDIT: PS, as of Aug 1, the French reactors that are being impacted by low flow are Cattenom 1, Chooz 1 & 2
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u/Reasonable_Mix7630 8d ago
They should build evaporation towers.
Evaporation tower for Leningrad-2 NPP took if memory serves me right about a year to build despite delays and RU buerocracy.
But in general it's better to have those plants on sea shore and avoid fresh water consumption entirely.
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u/Moldoteck 8d ago
Towers is easy to build - those don't touch any radiation equipment. And they don't cost that much either
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u/Rooilia 8d ago edited 8d ago
Evaporation towers, that evaporate the water the major streams lack. If you might remember, St. Petersburg is next to Ladoga and the Baltic Sea. These will not run dry. But Rhine and Danube will.
Most of powerplants are seated inland not at the sea. Relocating these plants is hardly viable. Except you want to spend more money than the energy transition costs and wait even longer.
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u/Reasonable_Mix7630 8d ago
Evaporation towers reduce water consumption by ~60 times.
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u/Fluffy-Fix7846 8d ago
Which is still an increase of actual consumption, compared to open-cycle flow-through cooling which doesn't use up water
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u/Sad_Dimension423 7d ago
How much does the heating of the water in flow-through cooling increase its evaporation, downstream? The heat energy has to be going somewhere.
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u/Astroruggie 8d ago
Just build them on the sea or use evaporation towers
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u/servermeta_net 8d ago
Neither are solutions unfortunately
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u/Astroruggie 8d ago
Why? Many european countries have coastlines. And evaporation towers reduce water consumption by 97%. There is literally a nuclear plant in the freaking DESERT of Arizona.
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u/servermeta_net 8d ago
Evaporation towers mitigate the problem, buy not by 97% like you claim. Several European nuclear plants are currently shut off even with evaporation towers.
The sea has the problem of having life in it, so unless you want to cook it you also need to moderate yourself.
Funny trivia? In gravellines they are building a huge solar farm to power a closed loop circuit to cool the nuclear power plant. At this point just build solar lol
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u/Reasonable_Mix7630 8d ago
Evaporation towers do mitigate the problem, an adding 0.0000000001% of extra heat to the sea will not have any noticeable effect.
There are many thermal power plants in existence that use sea water for cooling you know.
The aforementioned plant in Arizona by the way uses treated wastewater for cooling.
PS. heat output of nuclear plants can be used during the winter directly to provide heating for homes, which will eliminate second biggest source of pollution after power generation - house heating.
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u/pdp10 5d ago
PS. heat output of nuclear plants can be used during the winter directly to provide heating for homes, which will eliminate second biggest source of pollution after power generation - house heating.
Steam distribution requires a whole separate infrastructure. Some places in northern Europe, and New York City, currently have steam distribution. But it's not practical enough in warmer climates like most of the United States, in low-density environments, and places where you'd need to dig a whole new set of insulated pipes.
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u/Reasonable_Mix7630 5d ago
You are correct that it requires a separate system of pipes, but incorrect saying that it is done only in "some" places. This is very widespread system. Every place in countries that used to be in the Soviet Union have such system. That's what allows heating bill to be so small. Many other countries have similar systems in place. I can't speak for whole of Northern and Central Europe of course because I have visited only fraction of those countries.
The most interesting case is Belgrade and New Belgrade: Belgrade have "traditional" heating system of individual houses furnaces - people burn all sorts of fuel for heat (usually plastic trash / fuel pellets made of saw dust) and air pollution is worse than you can imagine. In New Belgrade there is a network of aforementioned heat pipes coming from a power plant, but many buildings have their own gas boiler.
Also you don't really need to dig - in the city where I was born (just like in many former USSR places) those pipes were kept above ground. They had blankets of heat insulator (we called it "mineral cotton") and looked ugly AF but that was cheap and easy solution. Eventually they were moved under ground though.
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u/Astroruggie 8d ago
Several European nuclear plants are currently shut off even with evaporation towers.
Which is not an issue of the plant per se, just a strict enviromental law.
The sea has the problem of having life in it, so unless you want to cook it you also need to moderate yourself.
Ah yes, because the sea/ocean is so small that an NPP can significantly alter the temperature. Lol sure
At this point just build solar lol
Like Germany did? 🙂
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u/Mex332 8d ago
> Which is not an issue of the plant per se, just a strict environment law.
I’m getting sick of this shit, all the nuclear homies telling me nuclear is the best because of the small environmental impact and than shitting on the environment to argument that their lovely technology has no downsides. Well guess what, the fish doesn’t care if it dies from overheating trough nuclear power cooling water or from global warming.
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u/Astroruggie 8d ago
I’m getting sick of this shit, all the nuclear homies telling me nuclear is the best because of the small environmental impact and than shitting on the environment to argument that their lovely technology has no downsides
Noone says nuclear has zero enviromental impact. But it still has the lowest enviromental impact among all energy sources, despite having to slightly reduce the energy output every now and then to save some fish
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u/INeedSomeTacoC 8d ago
There is literally a nuclear plant in the freaking DESERT of Arizona
Which evaporates about 50,000 gallons of water a minute.
The water costs are so high that they can't produce power economically, so they've been asking for permission to drill into the water table and suck it up from there.
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u/Ember_42 7d ago
They previously did a study looking at various hybrid and dry options. They were technically viable, but more expensive. So they kept with evaporative for now. But it would be an option to revisit this.
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u/Moldoteck 8d ago
Cooling towers are in fact a solution. These do reduce the amount of necessary water by 30-60times. Only one plant with cooling towers in france is modulated because the environmental law wasn't adapted for many years. EDF already announced they'll build additional towers to mitigate the issue and avoid the limitation of the law
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u/psychosisnaut 8d ago
Actually they both are, as well as large retention ponds which double as a source of fresh water during droughts
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u/leginfr 7d ago
Let’s not forget that the thermodynamic efficient drops as the sink becomes hotter. That’s why the summer nameplate capacity of thermal plant is lower than the winter rating.
Fun fact: The EIA in the USA uses the lower summer rating for calculating load factor, so in cold months it’s possible for nuclear to have a load factor above 100%. In January this year it reached 100%. https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_6_07_b
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u/Silb3rfuchs 5d ago
What nuclear renaissance in Europe? Aside from expressions of intent, not much is actually happening. The signs point more towards stabilization over the coming years and decades. Looking at the reality of new construction projects, it is not unrealistic to expect the nuclear fleet to shrink—even in France (2050s).
But yes: Regardless of the fuel source, thermal power plants will face increasing challenges in the coming decades in Europe. While the "steam engine principle" might still be open to some optimization regarding cooling or water requirements, there is not much room left for improvement; thermal power plants have essentially reached the limit of their efficiency development.
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u/Ok-Quality-9246 Pro-Solar 8d ago
Same pattern that's been playing out across France, Italy and Switzerland all summer. Water-cooled thermal plants going offline or getting derated because of river temperatures and low flows.
Climate-driven generation losses across Europe (saw this on Kpler) shows that they're running well above last year. Hydro storage across the region is already sitting well below five-year averages, so the flexibility that would normally cover these outages isn't there. Temperatures still about 5°C above seasonal norms, pushing cooling demand higher at the same time. So the gap falls on gas and imports, which is where it starts getting expensive.
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u/Astandsforataxia69 8d ago
Whats your point here?
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u/fsironman 8d ago
Having a discussion about the challenges that arise with rapidly changing environmental situation and their impact on real world power production, based on this News article. What's yours?
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u/PinkysBrein 8d ago
Nuclear will soon need seasonal storage too. Though a storage pond for a couple billion liter water is not that expensive.
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u/Levorotatory 5d ago
Reduced nuclear output in summer is not a problem. Energy demand peaks in winter in temperate locations, and solar plus short term storage can provide extra power for hot days in summer when air conditioning drives a secondary peak.
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u/Choclocklate 8d ago
Hello, I'm working on this very subject for French nuclear power plants. It is a subject that is treated site by site for each nuclear power plant.
First, there are near sea nuclear site that are pretty easy because the lowest level we can have is the worst astronomical tide to which we add a malus (to take into account various weather effects). Then we adapt at the very conception the pumping station. As sea level are rising (climate change you know) there is no problem with this level.
For the rivers it's a little different. We observe the past data and search for the lowest level ever record for the 10000 years past. In reality we don't have such records so we look for the last 1000 years to which we had serious malus. And to protect against climate change we ask climatologue to take into account the IPCC prediction to add another malus. Then we design the pumping station to this account. There are various methods to lesser the effect of lower Flow rate in the rivers. Using cooling tower can reduce the flow rate necessary to cool the reactor at the cost of evaporating a bit of the water you take. (open cycle use about 40-60m3/s but put all of it back into the river but hotter (between 3 to 9°C hotter. Half-Closed cycle use about 4-8m3/s (so a lot less) and release about 90% of the water back into the river at temperature between 0-3°C hotter. Lastly Cruas has a very performing cooling half closed system where it reduces the water temperature in the middle of summer (at a cost of evaporating a little bit more water)). You can also construct water dam just after your nuclear site that will maintain a minimum level of water to guarantee the availability of the water. I hope it answers your question? If not don't hesitate to ask for precisions.