jargo3 t1_jee109k wrote
Reply to comment by Kaz_55 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
​
>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.
​
​
>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.
Viewing a single comment thread. View all comments