tehrmuk t1_jeam7lr wrote
Reply to comment by holymurphy in The European Union to nearly double the share of renewables in the 27-nation bloc's energy consumption by 2030 amid efforts to become carbon neutral and ditch Russian fossil fuels. by chrisdh79
Nuclear power. So. Much. Nuclear.
And, FWIW, I applaud them for it.
netz_pirat t1_jeb3wk2 wrote
Yes, basically that. If you cover most of your energy needs with nuclear, switching to renewables isn't really a win in terms of co2.
If it's the best strategy going forward remains to be seen, replacing the aging fleet of reactors at an economical reasonable prices will be a monumental task, and the situation with the lack of cooling water in summer won't get easier either.
da2Pakaveli t1_jebc8jn wrote
Nuclear isn’t the one solves all solution either. You’re still looking at heat release as surplus thermal energy because a nuclear reactor isn’t better than a coal plant when it comes to degree of efficiency (around ~30%). Only with renewables that won’t happen because the energy in nature would end up as heat anyway because it’s already in the climate system, wether you use it or not.
This should be taken into account when scaling up.
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/49886
jargo3 t1_jebfatf wrote
The effect is absolutely miniscule and is a non-issue even if we would get all of our energy from nuclear. As the article you linked says it will be only be problem when we get to scifi-power source such as fusion.
Kaz_55 t1_jebinel wrote
That is not what the article actually claims though:
>Historical observations show a constant exponential growth of worldwide energy production. A continuation of this trend might be fueled or even amplified by the exploration of new carbon-free energy sources like fusion power.
The problem isn't "fusion", the problem is the exponential growth in energy production which leads to AHF. This is an inherent issue if you use heat engines to generate electricity - which both fission and fusion do. Nuclear power plants have a thermal efficiency ~33%:
while combined cycle gas powerplants can reach about twice of that.
This would be an issue with fission as well as with fusion. Seeing how you can scale neither fission nor fusion to even meet global base load demands that issue is mainly theoretical though. Basically all forms of nuclear power run into massive issues when you try to scale them beyond 1 TW globally.
https://phys.org/news/2011-05-nuclear-power-world-energy.html
jargo3 t1_jedlhry wrote
The effect of direct heat released from powerplants would be miniscule in the lifetime of any powerplants we are going to build in the near future, so making any decissions based on that doesn't make any sense.
The change of albedo caused by air pollution is more significant, but it isn't an issue with nuclear.
Also with those scales the change of earths average albedo with solar panels starts to have an effect, so I am not sure if renewables even are better in this context.
https://ui.adsabs.harvard.edu/abs/2020EGUGA..2218924S/abstract
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>This would be an issue with fission as well as with fusion. Seeing how you can scale neither fission nor fusion to even meet global base load demands that issue is mainly theoretical though. Basically all forms of nuclear power run into massive issues when you try to scale them beyond 1 TW globally.
https://phys.org/news/2011-05-nuclear-power-world-energy.html
If many of these points were true it would also make renewable energy transition impossible. New sources of uranium and minerals(such as rare earths needed by renewables) are made avalaible if the price increases.
Also this point just wrong.
>for 300,000 years. However, Abbott argues that these reactors’ complexity and cost makes them uncompetitive.) Moreover, as uranium is extracted, the uranium concentration of seawater decreases, so that greater and greater quantities of water are needed to be processed in order to extract the same amount of uranium. Abbott calculates that the volume of seawater that would need to be processed would become economically impractical in much less than 30 years
Extractring it from seawater isn't economically feasible, expect it is because it is because it can become economically unfeasible, after we exctract just 0.01% of the uranium from the seas, which in turn doesn't make any sense. How would such tiny a reduction in consetration would make process unfeasible? Not to mention that new uranium is dissolved in the seawater if concetration decreases.
I agree with you that going 100 % nuclear doesn't make sence, but quality of that study highly questionable.
Sol3dweller t1_jedukev wrote
I'd agree that the produced heat doesn't really play much of a role with respect to climate change.
> Also with those scales the change of earths average albedo with solar panels starts to have an effect, so I am not sure if renewables even are better in this context.
As your cited study points out. This heavily depends on where you place the solar panels. You can easily imagine that things like black-tiled rooftops or asphalted parking lots are actually improved in terms of absorbed heat by covering them with solar panels.
Kaz_55 t1_jedwpes wrote
>If many of these points were true it would also make renewable energy transition impossible. New sources of uranium and minerals(such as rare earths needed by renewables) are made avalaible if the price increases.
No it wouldn't, given the abundance of the elements involved and the impossibility of recycling irradiated materials on a viable timescale. Renewables ismply don't suffer from the inherent shortcomings nuclear has here. Extracting Uranium from other sources would make nuclear power even more unviable from an economic standpoint.
>How would such tiny a reduction in consetration would make process unfeasible?
Might I suggest reading the actual paper?
https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6021978
The issue is that the concentration in seawater is measured in ppb to begin with and the amount of water you need to filter to extract meaningful quantities of Uranium rises to infinity as the Uranium is extracted.
>This tells us that, for example, in as little as T = 30 years, a volume of seawater of 7x10^15 m3 would need to be processed - this is clearly impractical as it is over six times larger than the volume of total river outflow in the same time.
Nuclear is already the most expensive option out there. It simply isn't viable as a replacement for fossil fuels on a global scale, and given the growth in energy consumption it is bascially impossible to scale it to meet global base load demands.
jargo3 t1_jee109k wrote
​
>No it wouldn't, given the abundance of the elements involved and the impossibility of recycling irradiated materials on a viable timescale. Renewables ismply don't suffer from the inherent shortcomings nuclear has here. Extracting Uranium from other sources would make nuclear power even more unviable from an economic standpoint.
I didn't say anthing about nuclear waste. Renewable energy needs non-renewable minerals just like nuclear.
​
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>The issue is that the concentration in seawater is measured in ppb to begin with and the amount of water you need to filter to extract meaningful quantities of Uranium rises to infinity as the Uranium is extracted.
According to that paper 7.6 x 10^6 m3/s of sea water would need to processed to begin with. If you would reduce consentration by 0.01 % (30 years/ 300000 years) you would need to process 7,60076 x 10^6 m3/s of seawater after 30 years. Not 7x10^15 as the study claims. The calculations just doesn't make any sense. The equation doesn't take properly to account the total amount of seawater in the oceans.
​
>Nuclear is already the most expensive option out there. It simply isn't viable as a replacement for fossil fuels on a global scale, and given the growth in energy consumption it is bascially impossible to scale it to meet global base load demands.
I didn't say anything about the feasibility of using nuclear to replace all fossil fuels, so please do not argue against this strawman.
Kaz_55 t1_jefkxjn wrote
>I didn't say anthing about nuclear waste. Renewable energy needs non-renewable minerals just like nuclear.
But the article I brought up did. The claim being made isn't that nuclear needs non-renewable "minerals" while renewables don't. The issue is that "minerals" used in renewables are actually recoverable because they aren't irradiated.
>If you would reduce consentration by 0.01 % (30 years/ 300000 years) you would need to process 7,60076 x 10^6 m3/s of seawater after 30 years. Not 7x10^15 as the study claims.
Please actually read and at least try to comprehend the paper:
>This tells us that, for example, in as little as T ¼ 30 years, a volume of seawater of 7x10^15 m3 would need to be processed - this is clearly impractical as it is over six times larger than the volume of total river outflow in the same time.
This is the total volume of water that needs to be processed at that point, not volume per second. As stated, this would be six times the volume river global river input would be able to provide in the same timeframe, meaning this would be inherently unsustainable.
"Seawater" contains ~3 ppb Uranium, i.e. 3/1000000000, i.e. 0.0000003% of which 0.7% are actually fissile. Your initial concentration isn't 100%, it's 0.0000000021 %.
If we assume that 1 l of seawater has an approx mass of 1 kg (seawater is actually denser but let's ignore that) and assuming that the process was 100% efficient in recovering all the fissile Uranium (it wouldn't be, but let's also ignore that), filtering 7.6*10^6 m³/s of seawater would yield
7.6*10^9 kg/s * 0.0000000021% = 0.1596 kg
The energy contained in 1 kg of U235 (if the conversion was 100% efficient which is isn't but let's ignore that) is 83.15 TJ - ergo the energy you could extract from 0.1596 kg is 13.27074 TJ or ~1.33*10^13 J. Let's just ignore that the thermal efficiency of nuclear plants is ~33% to begin with.
Extraction probably requires pumping all that seawater through a filtration plant, chemical treatment, whatever. Let's assume that all we have is water and U235 - no additional impurities, no uranium compounds that need to be purified and extracted etc. Let's assume we could simply separate water and uranium via reverse osmosis and ignore all the additional steps and energy that would actually be required to use it in a nuclear reactor.
Filtration via reverse osmosis of 1 m³ of water requires 3 - 5.5 kWh. Let's be optimistic and go with 3 kWh/m³ - that's 10800000 J/m³.
Ergo we would need 8.21*10^13 J to filter all of that U235 from the 7600000 m³ we need to process.
Or in other words, extracting uranium from sea water has a negative energy yield, even if we assume that we could somehow seperate it via simple reverse osmosis and the energy conversion was 100% efficient. Which it is not.
>I didn't say anything about the feasibility of using nuclear to replace all fossil fuels, so please do not argue against this strawman.
Even providing global base load would not be feasible let alone economically viable or possible on any meaningful timescale. Given that nuclear isn't a solution for anything, not actually needed and provides no meaningful benefit, what exactely is the point of wasting money and resources on this?
There is a reason why nuclear has been stagnating for the last decades and will play an ever diminishing role in the coming decades:
Nuclear is a dead-end for terrestial utility scale power generation. Renewables are the only feasible way to decarbonize our energy sector.
da2Pakaveli t1_jebh1ej wrote
On a global scale, so far:
So far, the AHF has no relevant climate impact on a global scale. However, given continued growth in a decarbonised world, the AHF can become a relevant factor of post-greenhouse gas warming in the relatively near future within the next century. Also, on a local scale, even today the AHF is a non- negligible process. This holds not only for the direct AHF impact in urbanised areas, but also for remote, large-scale areas like the sea ice near Greenland due to the ice-albedo feedback and impacts on the ocean circulation. The analysis of CLIMBER-3α has shown that a forcing as small as the AHF in the current years (roughly 2% of the CO2 forcing) can influence ocean circulation in such a way that a temperature change of more than ±0.3 K can result in the Arctic region with significant changes in the sea ice cover.
jargo3 t1_jedmsam wrote
The effect of direct heat released from powerplants would be miniscule in the lifetime of any powerplants we are going to build in the near future(in the next 30 years), so making any decissions based on that doesn't make any sense.
The change of albedo caused by air pollution is more significant, but it isn't an issue with nuclear.
Also with those scales the change of earths average albedo with solar panels starts to have an effect, so I am not sure if renewables even are better in this context.
https://ui.adsabs.harvard.edu/abs/2020EGUGA..2218924S/abstract
Scytle t1_jebet1q wrote
Nuclear power will also stop working as the planet warms, because the temp difference in the water source you are using to cool the plant will not be enough to keep the plant running. This already happens in some southern nuclear power plants in the US.
Can't cool your reactor if your "coolant" water comes in too hot.
Blakut t1_jebf9hx wrote
uhm when the outside is hot enough to not cool your reactor anymore we'd all be dead.
Scytle t1_jebhiy1 wrote
the water doesn't have to be that warm before it fails to cool your nuclear reactor down effectively. This is already happening in france https://www.theguardian.com/business/2022/aug/03/edf-to-reduce-nuclear-power-output-as-french-river-temperatures-rise
IngloriousTom t1_jec0q6k wrote
Did you even read your own source...
> to ensure the water used to cool the plants will not harm wildlife when it is released back into the rivers.
This is a legal requirement, not a technical one.
The water won't ever be too hot to cool down the reactors. How hot do you think the nuclear reactors are, 40°?
Rondaru t1_jedpixw wrote
"Legal" requirement sounds like you don't really care if you'd kill thousands if not millions of fish by giving them a heat stroke.
Power plants need to cool down their hot cooling water to harmless levels before releasing it back into the lakes or rivers. That is what those giant cooling towers are for. But on hot summer days, their efficiency is greatly reduced and that limits the plant's thermal waste output and thus production capacity. And that is why they should be paired with solar energy to fill the gap on such hot days.
IngloriousTom t1_jedt7ew wrote
> "Legal" requirement sounds like you don't really care if you'd kill thousands if not millions of fish by giving them a heat stroke.
Given that this law has been repealed this summer during the worst drought of recent history without any consequences, it's fair to say this piece of legislation was unnecessarily cautious.
In any cases that's not related to what OP said about water being too hot to cool down the reactors, with a lot of confidence.
Scytle t1_jec4vwa wrote
you can't just boil a river...what are you talking about? You can't just destroy every river that a nuclear plant is on, the fact that the water is too hot to return to the river...means its too hot.
Inphearian t1_jec9xvh wrote
Really jumping around on points here
IngloriousTom t1_jedfmuq wrote
Dude, I won't let you move goalposts. You literally said that:
> the temp difference in the water source you are using to cool the plant will not be enough to keep the plant running.
> Can't cool your reactor if your "coolant" water comes in too hot.
Stop making excuses and be grateful you learnt basic thermodynamics today.
And stop parroting this shit anymore.
IngloriousTom t1_jec2xc3 wrote
> Can't cool your reactor if your "coolant" water comes in too hot.
How are people even upvoting you? Even at 80° the water would be cool enough for my freaking GPU...
da2Pakaveli t1_jebf4jt wrote
Also rivers increasingly drying up and water shortages are problematic for cooling.
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