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One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. One square kilometer of solar panels can theoretically produce th

One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. One square kilometer of solar panels can theoretically produce the same amount (as 50cm^3 U235) in a day. I'll take this bet. Edit: Tried to edit the edit but somehow deleted the rest of the edit. It was something to the tune of how a big problem with renewables is the fact that peak solar production does not match peak energy consumption, and storage is very difficult, so realistically we'll need a wide variety of energy options to fully transition to renewables. Nuclear is reliable and to some degree adjustable, helping to alleviate the storage issue. Basically, it's my opinion that nuclear works well with other renewable sources, and a full renewable transition will certainly involve more of it.

echelon 3y ago
We need two things: - More energy - Energy diversification That includes nuclear, solar, and even more fossil fuels as we wean ourselves off of them. Writing off any form of energy is ideological, not practical.
- internetter 3y ago
  Agreed minus the fossil fuels bit. It's my belief we should not further scale that infrastructure.
adonovan 3y ago
Perhaps I fail to understand, but doesn't this comparison depend on a number of parameters such as the total reactor fuel load and enrichment, the burn rate, the cost of nuclear fuel, the cost of solar PV, the lifetimes of each system, and the relative process efficiencies (notably the cost of decommissioning nuclear)? Otherwise you might as well say a teaspoon (or whatever) of water has as much potential fusion energy as 1 Kg U235 at a fraction of the price. ;-)
- internetter 3y ago
  Yes, the amount of estimations I made to get to that number is absurd, and very much "best case" with no regard for inefficiencies (both nuclear and solar systems are currently leaving lots on the table).
- credit_guy 3y ago
  Small nitpick: one teaspoon of water has much less potential fusion energy than 1 kg of U235, and actually much much less than 1g of U235, even allowing for fusion technology that does not exist and will not exist in 50 years. Here's why. The Sun transforms hydrogen into helium. But that's a fairly complex chain and nobody in the industry or academia is trying to replicate that. When people talk about fusion, here's [1] the reactions they are considering. The best yielding fusion reaction is deuterium-tritium and deuterium-helium3 [1]. Tritium and helium-3 virtually don't occur naturally on Earth, and deuterium is very rare, at about 0.02% of the hydrogen. A teaspoon of water contains about 0.5 grams of hydrogen, and out of that about 0.0001 grams of deuterium. Let's say that someone magically brings the necessary tritium or helium-3. How does that compare with 1 gram of U235? The fission of 1 nucleus of U235 yields about 190 MeV of energy. 1 MeV is one megaelectronvolt, and is a unit of energy. It does not matter how it translates into joules or watt-hours. It is the unit used when talking about fission and fusion. So, 235 nucleons produce 190 MeV, which is about 0.8 MeV per nucleon. The two reactions mentioned involve 5 nucleons and yield about 18 MeV, which means 3.6 MeV per nucleon or 4.5 times more per nucleon than U235. So, even if all the hydrogen in the one teaspoon of water was Deuterium and Tritium, in the correct ratios to do the fusion, we'd get only 4.5 times more energy than from one gram of U235. In reality, from one teaspoon of water we'd extract a very tiny amount of deuterium that's usable, and we'd need to breed Tritium or Helium-3 separately. By the way, separating deuterium from water is a very expensive process. The Nazis tried to do it during WW2, and they were doing it in Norway. Once the British special forces destroyed the plant, the Nazis could not restart the heavy water production, and their atomic project basically stopped then and there. [1] https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_ca...
wongarsu 3y ago
The US doesn't lack space. But investors like a quick return on investment; meanwhile nuclear reactors only make sense if you bet on high electricity prices for the next ~70 years. The time a nuclear plant spends on construction and decommissioning is about the same as the total lifetime of a solar installation.
- smegger001 3y ago
  How about recognizing that externalities of letting corporations do whats best for their own short term profits are costly to society, and that having safe cheap constant power is a social good that makes having government run nuclear power be a good idea. how about we not let the same people that have spent the last 50 years knowingly destroy the environment and hide their culpability be the ones to make the decision. how about we as a society finally fulfill the promise of power to cheap to meter that we were told back in nuclears golden age before the carbon industry start the smear campaign against nuclear.
  - RcouF1uZ4gsC 3y ago
    > before the carbon industry start the smear campaign against nuclear. The environmental Greens had a lot to do with the smear. Even recently, they were the ones who pushed for the shutdown of German nuclear power which ended up increasing German CO2 output.
    - ikt 3y ago
      > which ended up increasing German CO2 output. That's temporary, soon that will go back down again
    - _ph_ 3y ago
      No need for pushing as the coalition of CDU/CSU and FDP had decided to shut down the reactors in Germany and had set the date.
      - hef19898 3y ago
tiffanyg 3y ago
Not unreasonable, but I would point out two options (not the only): 1) "Water batteries" - highly efficient (far more than the 'chemical' you are apparently referring to) & responsive 2) Methods for using 'renewables' to produce &/ support production of chemical fuels - with the added draw / potential goal of 'closing' the 'carbon cycle' As to #2, one of the ideals that has been kicked around for decades is to do something like: use 'renewables' to sequester CO2 from the atmosphere and convert it into something like butanol, for example. Now, last I was up-to-date on any of this sort of work (~10+ years ago), the economics were not favorable. Certain types of commodity chemical production with 'biological basis' (another type of renewable, typically) had much more favorable properties economically. And, indeed, you do see, for example, (thermo)plastic products made from chemicals like "PLA" increasingly. But, the "biofuels" concept is / was much more challenging, especially as "fracking" technology made great leaps etc. Nuclear has its pros and cons - blanket disavowal is fatuous. Nevertheless, there are substantially more options, systems, technologies, etc. in development and production than are often discussed in too many of the pro-nuke(s) / no nuke(s) 'sniping' chains that have been prevalent in society & on the internet since I was a wee tyke myself.
- internetter 3y ago
  > use 'renewables' to sequester CO2 from the atmosphere and convert it into something like butanol, for example. are you referring to P2X? I think P2X is an awesome solution for existing infrastructure, but it's obviously not particularly efficient. I am excited about pumped storage as well, but my fear there is we'll run out of sites, and obviously the 80% efficiency is still not ideal. By no means am I arguing nuclear is a one size fits all solution.
- concordDance 3y ago
  > 1) "Water batteries" - highly efficient (far more than the 'chemical' you are apparently referring to) & responsive "Highly efficient" is very vague. What matters here are the numbers: W/$ J/$ % round trip losses % losses per hour Number of cycles before replacement needed Response time Do you have them?
cool_dude85 3y ago
Nuclear is baseload and is the exact opposite of "instantly fired up". Best tech for that is gas or battery.
- tonyhb 3y ago
  Cant control rods can be lifted or inserted to meet demand?
  - cool_dude85 3y ago
    There's typically a range of operation, so you can adjust a hundred MW but you can't drop to 0 or spin up from standstill without a time consuming process. Edit: also, the economics are such that you rarely want to drop load from a nuclear plant unless it's offline or for system reasons. The fuel cost is negligible so you'd rather turn off your gas plant or lower the coal plant and save on those fuels.
    - belorn 3y ago
      That assume we still allow coal, oil or gas power plant to exist in the power grid. We should probably not assume that to be the case, especially after the temperatures rises to a break point and some of the major climate change crisis occurs.
      - xorcist 3y ago
        None of the commercially available (Western) reactor designs today are fast load followers, so you are dependent on having gas or hydro when you project for new nuclear power plants. That's one part of the reason why this stuff is politically charged. From what I understand it's not a theoretical constraint, but mostly a lack of enough commercial interest for any other design. But it is what it is.
  - throw0101b 3y ago
    > Cant control rods can be lifted or inserted to meet demand? Thermally it is difficult to dial a reactor up and down. Generally the way nuclear power is modified is by not-sending the steam to generators through a by-pass and quenching their heat in some fashion. So thermal generation stays at 100% (or whatever), but electrical generation output can be dropped.
margalabargala 3y ago
> One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. One square kilometer of solar panels can theoretically produce the same amount (as 50cm^3 U235) in a day. Does the US have more 50cm^3 sized blocks of U235, or more square kilometers of land with low land values and high annual insolation? There's an estimated 6 million tonnes of mineable uranium reserves in the world [0]. Of which 0.72% is U-235, so we have a worldwide reserve of 43200 tonnes, or 43.2 million Kg U-235. Arizona is about 300k square kilometers. If we covered an area 10% the size of Arizona in solar panels, then they would have produced more energy than all the world's known U-235 in just four years. And would continue producing after those four years are up. [0] https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/world-uranium-mining-production.aspx https://world-nuclear.org/information-library/nuclear-fuel-c...
- Turing_Machine 3y ago
  > If we covered an area 10% the size of Arizona in solar panels And what are the various Friends of Rare Bugs and Small Furry Animals groups doing in the meantime? I joke, but even I would balk at the environmental impact of that. Certainly it's going to be greater than any equivalent nuclear installation. > Of which 0.72% is U-235 Fortunately we're not limited to U-235. With breeder reactors, there's enough nuclear fuel to run human civilization for billions-with-a-b of years.
  - jodrellblank 3y ago
    Cover 4,000 square miles of the USA in surface car parks[1] and that's freedom. Suggest covering 11,000 square miles of desert in solar panels which don't stop land being used for grazing or crop growing or insects or wildlife, and that's environmental distruction that "even" you would balk at. [1] https://www.archdaily.com/976069/when-5-percent-of-the-united-states-is-covered-by-parking-lots-how-do-we-redesign-our-cities https://www.archdaily.com/976069/when-5-percent-of-the-unite...
    - internetter 3y ago
duped 3y ago
The uranium can produce power when it's dark outside, unlike the solar panels. I wouldn't bet against clean energy that can produce on demand. We'll always need it from somewhere.
est31 3y ago
> One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. That's missing the huge and expensive nuclear power plant around that kilogram of uranium. If you don't account for the conversion device (for which solar is cheaper per GJ than nuclear power plants), then light is a much better medium: assuming 15% efficiency, which is a conservative estimate, solar panels can convert one kilogram of solar light (remember e=mc^2) into 13.5 terajoules of electricity. https://www.wolframalpha.com/input?i=1+kg+*+c%5E2+*+15%25+in+TJ https://www.wolframalpha.com/input?i=1+kg+*+c%5E2+*+15%25+in... The sun bombards our planet with around 61 metric tons of light per day: https://www.wolframalpha.com/input?i=2+*+pi+*+radius+of+earth%5E2+*+6+kwh+%2F+m%5E2+%2F+c%5E2 https://www.wolframalpha.com/input?i=2+*+pi+*+radius+of+eart... Where the 6 kwh/m^2 come from: https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on_Earth's_surface https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on...
- datameta 3y ago
  Hey thanks for adding links to formulas. Great use of wolfram alpha imo.
- apatheticonion 3y ago
  I'm curious how the numbers stack up of completed plants - but I am not very good at math and don't have a great understanding of electricity units, especially at the grid scale and big numbers. Any chance you could help compare the construction cost of this nuclear plant to another recently constructed solar or wind farm measured against... I guess capacity? Given the intermittent nature of solar/wind, does capacity even make sense to compare in a context without supporting batteries? I'll give it a shot but I am probably super wrong. ** Nuclear: I'll use the plant from the article https://en.wikipedia.org/wiki/Vogtle_Electric_Generating_Plant https://en.wikipedia.org/wiki/Vogtle_Electric_Generating_Pla... Construction costs 18b USD (does that include loans?) Nameplate capacity of 2302MW Used capacity is 91% so 2094MW $18b / nameplate capacity = $7.8 USD per rated W $18b / used capacity = $8.60 per realized W ** Solar (excluding batteries): I picked a relatively large, recent, US based solar farm from the list of plants in wikipedia Agua Caliente Solar Project (2016) https://en.wikipedia.org/wiki/Agua_Caliente_Solar_Project https://en.wikipedia.org/wiki/Agua_Caliente_Solar_Project Construction costs 1.8b USD Nameplate capacity of 290 MW Used capacity is 28% so 81 MW $1.8b / nameplate capacity = $6.2 USD per rated W $1.8b / used capacity = $22 USD per realized W (that can't be right?) ** Note: I don't know if my math is right, I don't know if the costs factor in loans, also the nameplate capacity for the nuclear plant is MWe and the solar plant is MWac so I am unsure how that works out.
sandworm101 3y ago
But remember that a square kilometer of solar panels needs maybe ten square kilometers of actual land. Anywhere other than at the equator, the panels need to be spaced far enough apart not to shadow each other. On a north-facing slop they would be even more spaced out. Do that in two dimensions, so they can track the sun, and keeping one square meter of panels perpendicular to the sun requires a suprisingly large footprint. And trees. Clearcutting forests to make room for a solar panels just seems wrong, a Captain Planet style of evil. There are all sorts of places where the terrain just isnt suited.
- ceejayoz 3y ago
  Good thing that cube of uranium doesn’t need any extra space around it! We can just line them all up next to each other. Criticality accident? What’s that? Clear cutting forest to put in solar isn’t likely to be cost-efficient. There’s plenty of shitty desert and mountainside land available.
- mminer237 3y ago
  It's not 10x. The optimal ground coverage ratio in the South even for tracking panels is like 30%: https://www.sciencedirect.com/science/article/pii/S0038092X23002682 https://www.sciencedirect.com/science/article/pii/S0038092X2... Most of the US isn't wooded. I don't think a significant number of projects propose clear-cutting to build solar farms. I don't know where that came from.
  - sandworm101 3y ago
    Try where i am, the pacific northwest. Its all mountains and trees. Large solar farms are always tricky, even residential rooftop solar often runs into issues with trees.
    - hn_throwaway_99 3y ago
      If only it were possible to transmit electricity from one place to another... Seriously, while a lot has been written about the need to update the grid and install more long distance transmission lines to support renewables, even with the current grid it makes much more sense to install wind and solar in locations where it is more efficient and then transmit the electricity elsewhere. In Texas, most of the wind farms are in West Texas hundreds of miles away from Houston, for example.
shwouchk 3y ago
One interesting point that I think is often missed, is that solar and wind produce energy roughly at an anticadence to each other and so storage is of significantly less of a requirement than one might imagine.
deleted 3y ago
[deleted]
ericd 3y ago
Can we not overbuild solar and wind such that the troughs are nearly good enough, combined with high voltage cross-regional transmission lines, and limited storage for buffer? Solar panels are absurdly cheap, and the world has a lot of equatorial desert.
- angiosperm 3y ago
  Yes, we can, and will do. Solar is so cheap that 4x overbuild is still cheaper than nukes, and cost is still plummeting.
asylteltine 3y ago
Nuclear is the way forward. It’s a damn shame hippies stopped us from leveraging it. We literally wouldn’t have climate change if we kept increasing nuclear power plants in the 70s. It’s just a no brainer. Solar and wind are great but the amount of power they generate may as well be 0 compared to nuclear.
- Faaak 3y ago
  > We literally wouldn’t have climate change if we kept increasing nuclear power plants in the 70s I highly doubt this
  - asylteltine 3y ago
    Methane and coal is the largest driver of climate change
- simplyluke 3y ago
  > Solar and wind are great but the amount of power they generate may as well be 0 compared to nuclear. This is very untrue both measured in absolute numbers, and in cost/kwh. Nuclear is 2x solar and wind, both of which are decreasing in cost rapidly YoY. https://www.statista.com/statistics/194327/estimated-levelized-capital-cost-of-energy-generation-in-the-us/ https://www.statista.com/statistics/194327/estimated-leveliz...
ken47 3y ago
You're comparing a one-time-use resource in U235 vs. the land required for a solar plant, which will last indefinitely for all intents and purposes. Adding the "in a day" constraint is quite misleading in your comment when that is not the long-term limiting factor. Let's not forget that the externalities of nuclear power are generally much more costly than solar / wind.
nojvek 3y ago
We need to move away from coal as soon as we can. Coal is worst CO2 pollutant and not that energy dense. Move to a mixture of wind, solar, geothermal, hydro, nuclear - whatever makes sense. When the last coal powered plant is shut off in US, we should celebrate that as a day off for everyone.
AtlasBarfed 3y ago
Have you seen the Lazard lcoe numbers? Nukes are 6x more expensive than wind solar. And wind and especially solar have more economies of scale and materials research to make them even cheaper. This comes from a LFTR fanboy. Boy howdy do I wish economical nuclear existed. But 6x as expensive? That ain't all red tape. I think of course that LFTR has a path to cheaper nuclear with breeding and near waste elimination, full fuel use, safety, and scalability. But I don't think it will ever beat solar, especially once mature multifunction silicon perovskite cells or something like that and salt water batteries develop. I hope to be proven wrong.nyclest power is so cool.

echelon 3y ago

We need two things: - More energy - Energy diversification That includes nuclear, solar, and even more fossil fuels as we wean ourselves off of them. Writing off any form of energy is ideological, not practical.

internetter 3y ago
Agreed minus the fossil fuels bit. It's my belief we should not further scale that infrastructure.

adonovan 3y ago

Perhaps I fail to understand, but doesn't this comparison depend on a number of parameters such as the total reactor fuel load and enrichment, the burn rate, the cost of nuclear fuel, the cost of solar PV, the lifetimes of each system, and the relative process efficiencies (notably the cost of decommissioning nuclear)? Otherwise you might as well say a teaspoon (or whatever) of water has as much potential fusion energy as 1 Kg U235 at a fraction of the price. ;-)

internetter 3y ago
Yes, the amount of estimations I made to get to that number is absurd, and very much "best case" with no regard for inefficiencies (both nuclear and solar systems are currently leaving lots on the table).
credit_guy 3y ago
Small nitpick: one teaspoon of water has much less potential fusion energy than 1 kg of U235, and actually much much less than 1g of U235, even allowing for fusion technology that does not exist and will not exist in 50 years. Here's why. The Sun transforms hydrogen into helium. But that's a fairly complex chain and nobody in the industry or academia is trying to replicate that. When people talk about fusion, here's [1] the reactions they are considering. The best yielding fusion reaction is deuterium-tritium and deuterium-helium3 [1]. Tritium and helium-3 virtually don't occur naturally on Earth, and deuterium is very rare, at about 0.02% of the hydrogen. A teaspoon of water contains about 0.5 grams of hydrogen, and out of that about 0.0001 grams of deuterium. Let's say that someone magically brings the necessary tritium or helium-3. How does that compare with 1 gram of U235? The fission of 1 nucleus of U235 yields about 190 MeV of energy. 1 MeV is one megaelectronvolt, and is a unit of energy. It does not matter how it translates into joules or watt-hours. It is the unit used when talking about fission and fusion. So, 235 nucleons produce 190 MeV, which is about 0.8 MeV per nucleon. The two reactions mentioned involve 5 nucleons and yield about 18 MeV, which means 3.6 MeV per nucleon or 4.5 times more per nucleon than U235. So, even if all the hydrogen in the one teaspoon of water was Deuterium and Tritium, in the correct ratios to do the fusion, we'd get only 4.5 times more energy than from one gram of U235. In reality, from one teaspoon of water we'd extract a very tiny amount of deuterium that's usable, and we'd need to breed Tritium or Helium-3 separately. By the way, separating deuterium from water is a very expensive process. The Nazis tried to do it during WW2, and they were doing it in Norway. Once the British special forces destroyed the plant, the Nazis could not restart the heavy water production, and their atomic project basically stopped then and there. [1] https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_ca...

wongarsu 3y ago

The US doesn't lack space. But investors like a quick return on investment; meanwhile nuclear reactors only make sense if you bet on high electricity prices for the next ~70 years. The time a nuclear plant spends on construction and decommissioning is about the same as the total lifetime of a solar installation.

smegger001 3y ago
How about recognizing that externalities of letting corporations do whats best for their own short term profits are costly to society, and that having safe cheap constant power is a social good that makes having government run nuclear power be a good idea. how about we not let the same people that have spent the last 50 years knowingly destroy the environment and hide their culpability be the ones to make the decision. how about we as a society finally fulfill the promise of power to cheap to meter that we were told back in nuclears golden age before the carbon industry start the smear campaign against nuclear.
- RcouF1uZ4gsC 3y ago
  > before the carbon industry start the smear campaign against nuclear. The environmental Greens had a lot to do with the smear. Even recently, they were the ones who pushed for the shutdown of German nuclear power which ended up increasing German CO2 output.
  - ikt 3y ago
    > which ended up increasing German CO2 output. That's temporary, soon that will go back down again
  - _ph_ 3y ago
    No need for pushing as the coalition of CDU/CSU and FDP had decided to shut down the reactors in Germany and had set the date.
    - hef19898 3y ago

tiffanyg 3y ago

Not unreasonable, but I would point out two options (not the only): 1) "Water batteries" - highly efficient (far more than the 'chemical' you are apparently referring to) & responsive 2) Methods for using 'renewables' to produce &/ support production of chemical fuels - with the added draw / potential goal of 'closing' the 'carbon cycle' As to #2, one of the ideals that has been kicked around for decades is to do something like: use 'renewables' to sequester CO2 from the atmosphere and convert it into something like butanol, for example. Now, last I was up-to-date on any of this sort of work (~10+ years ago), the economics were not favorable. Certain types of commodity chemical production with 'biological basis' (another type of renewable, typically) had much more favorable properties economically. And, indeed, you do see, for example, (thermo)plastic products made from chemicals like "PLA" increasingly. But, the "biofuels" concept is / was much more challenging, especially as "fracking" technology made great leaps etc. Nuclear has its pros and cons - blanket disavowal is fatuous. Nevertheless, there are substantially more options, systems, technologies, etc. in development and production than are often discussed in too many of the pro-nuke(s) / no nuke(s) 'sniping' chains that have been prevalent in society & on the internet since I was a wee tyke myself.

internetter 3y ago
> use 'renewables' to sequester CO2 from the atmosphere and convert it into something like butanol, for example. are you referring to P2X? I think P2X is an awesome solution for existing infrastructure, but it's obviously not particularly efficient. I am excited about pumped storage as well, but my fear there is we'll run out of sites, and obviously the 80% efficiency is still not ideal. By no means am I arguing nuclear is a one size fits all solution.
concordDance 3y ago
> 1) "Water batteries" - highly efficient (far more than the 'chemical' you are apparently referring to) & responsive "Highly efficient" is very vague. What matters here are the numbers: W/$ J/$ % round trip losses % losses per hour Number of cycles before replacement needed Response time Do you have them?

cool_dude85 3y ago

Nuclear is baseload and is the exact opposite of "instantly fired up". Best tech for that is gas or battery.

tonyhb 3y ago
Cant control rods can be lifted or inserted to meet demand?
- cool_dude85 3y ago
  There's typically a range of operation, so you can adjust a hundred MW but you can't drop to 0 or spin up from standstill without a time consuming process. Edit: also, the economics are such that you rarely want to drop load from a nuclear plant unless it's offline or for system reasons. The fuel cost is negligible so you'd rather turn off your gas plant or lower the coal plant and save on those fuels.
  - belorn 3y ago
    That assume we still allow coal, oil or gas power plant to exist in the power grid. We should probably not assume that to be the case, especially after the temperatures rises to a break point and some of the major climate change crisis occurs.
    - xorcist 3y ago
      None of the commercially available (Western) reactor designs today are fast load followers, so you are dependent on having gas or hydro when you project for new nuclear power plants. That's one part of the reason why this stuff is politically charged. From what I understand it's not a theoretical constraint, but mostly a lack of enough commercial interest for any other design. But it is what it is.
- throw0101b 3y ago
  > Cant control rods can be lifted or inserted to meet demand? Thermally it is difficult to dial a reactor up and down. Generally the way nuclear power is modified is by not-sending the steam to generators through a by-pass and quenching their heat in some fashion. So thermal generation stays at 100% (or whatever), but electrical generation output can be dropped.

margalabargala 3y ago

> One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. One square kilometer of solar panels can theoretically produce the same amount (as 50cm^3 U235) in a day. Does the US have more 50cm^3 sized blocks of U235, or more square kilometers of land with low land values and high annual insolation? There's an estimated 6 million tonnes of mineable uranium reserves in the world [0]. Of which 0.72% is U-235, so we have a worldwide reserve of 43200 tonnes, or 43.2 million Kg U-235. Arizona is about 300k square kilometers. If we covered an area 10% the size of Arizona in solar panels, then they would have produced more energy than all the world's known U-235 in just four years. And would continue producing after those four years are up. [0] https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/world-uranium-mining-production.aspx https://world-nuclear.org/information-library/nuclear-fuel-c...

Turing_Machine 3y ago
> If we covered an area 10% the size of Arizona in solar panels And what are the various Friends of Rare Bugs and Small Furry Animals groups doing in the meantime? I joke, but even I would balk at the environmental impact of that. Certainly it's going to be greater than any equivalent nuclear installation. > Of which 0.72% is U-235 Fortunately we're not limited to U-235. With breeder reactors, there's enough nuclear fuel to run human civilization for billions-with-a-b of years.
- jodrellblank 3y ago
  Cover 4,000 square miles of the USA in surface car parks[1] and that's freedom. Suggest covering 11,000 square miles of desert in solar panels which don't stop land being used for grazing or crop growing or insects or wildlife, and that's environmental distruction that "even" you would balk at. [1] https://www.archdaily.com/976069/when-5-percent-of-the-united-states-is-covered-by-parking-lots-how-do-we-redesign-our-cities https://www.archdaily.com/976069/when-5-percent-of-the-unite...
  - internetter 3y ago

duped 3y ago

The uranium can produce power when it's dark outside, unlike the solar panels. I wouldn't bet against clean energy that can produce on demand. We'll always need it from somewhere.

est31 3y ago

> One kilogram of uranium-235 (50 cm^3) can theoretically produce about 20 terajoules of energy. That's missing the huge and expensive nuclear power plant around that kilogram of uranium. If you don't account for the conversion device (for which solar is cheaper per GJ than nuclear power plants), then light is a much better medium: assuming 15% efficiency, which is a conservative estimate, solar panels can convert one kilogram of solar light (remember e=mc^2) into 13.5 terajoules of electricity. https://www.wolframalpha.com/input?i=1+kg+*+c%5E2+*+15%25+in+TJ https://www.wolframalpha.com/input?i=1+kg+*+c%5E2+*+15%25+in... The sun bombards our planet with around 61 metric tons of light per day: https://www.wolframalpha.com/input?i=2+*+pi+*+radius+of+earth%5E2+*+6+kwh+%2F+m%5E2+%2F+c%5E2 https://www.wolframalpha.com/input?i=2+*+pi+*+radius+of+eart... Where the 6 kwh/m^2 come from: https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on_Earth's_surface https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on...

datameta 3y ago
Hey thanks for adding links to formulas. Great use of wolfram alpha imo.
apatheticonion 3y ago
I'm curious how the numbers stack up of completed plants - but I am not very good at math and don't have a great understanding of electricity units, especially at the grid scale and big numbers. Any chance you could help compare the construction cost of this nuclear plant to another recently constructed solar or wind farm measured against... I guess capacity? Given the intermittent nature of solar/wind, does capacity even make sense to compare in a context without supporting batteries? I'll give it a shot but I am probably super wrong. ** Nuclear: I'll use the plant from the article https://en.wikipedia.org/wiki/Vogtle_Electric_Generating_Plant https://en.wikipedia.org/wiki/Vogtle_Electric_Generating_Pla... Construction costs 18b USD (does that include loans?) Nameplate capacity of 2302MW Used capacity is 91% so 2094MW $18b / nameplate capacity = $7.8 USD per rated W $18b / used capacity = $8.60 per realized W ** Solar (excluding batteries): I picked a relatively large, recent, US based solar farm from the list of plants in wikipedia Agua Caliente Solar Project (2016) https://en.wikipedia.org/wiki/Agua_Caliente_Solar_Project https://en.wikipedia.org/wiki/Agua_Caliente_Solar_Project Construction costs 1.8b USD Nameplate capacity of 290 MW Used capacity is 28% so 81 MW $1.8b / nameplate capacity = $6.2 USD per rated W $1.8b / used capacity = $22 USD per realized W (that can't be right?) ** Note: I don't know if my math is right, I don't know if the costs factor in loans, also the nameplate capacity for the nuclear plant is MWe and the solar plant is MWac so I am unsure how that works out.

sandworm101 3y ago

But remember that a square kilometer of solar panels needs maybe ten square kilometers of actual land. Anywhere other than at the equator, the panels need to be spaced far enough apart not to shadow each other. On a north-facing slop they would be even more spaced out. Do that in two dimensions, so they can track the sun, and keeping one square meter of panels perpendicular to the sun requires a suprisingly large footprint. And trees. Clearcutting forests to make room for a solar panels just seems wrong, a Captain Planet style of evil. There are all sorts of places where the terrain just isnt suited.

ceejayoz 3y ago
Good thing that cube of uranium doesn’t need any extra space around it! We can just line them all up next to each other. Criticality accident? What’s that? Clear cutting forest to put in solar isn’t likely to be cost-efficient. There’s plenty of shitty desert and mountainside land available.
mminer237 3y ago
It's not 10x. The optimal ground coverage ratio in the South even for tracking panels is like 30%: https://www.sciencedirect.com/science/article/pii/S0038092X23002682 https://www.sciencedirect.com/science/article/pii/S0038092X2... Most of the US isn't wooded. I don't think a significant number of projects propose clear-cutting to build solar farms. I don't know where that came from.
- sandworm101 3y ago
  Try where i am, the pacific northwest. Its all mountains and trees. Large solar farms are always tricky, even residential rooftop solar often runs into issues with trees.
  - hn_throwaway_99 3y ago
    If only it were possible to transmit electricity from one place to another... Seriously, while a lot has been written about the need to update the grid and install more long distance transmission lines to support renewables, even with the current grid it makes much more sense to install wind and solar in locations where it is more efficient and then transmit the electricity elsewhere. In Texas, most of the wind farms are in West Texas hundreds of miles away from Houston, for example.

shwouchk 3y ago

One interesting point that I think is often missed, is that solar and wind produce energy roughly at an anticadence to each other and so storage is of significantly less of a requirement than one might imagine.

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ericd 3y ago

Can we not overbuild solar and wind such that the troughs are nearly good enough, combined with high voltage cross-regional transmission lines, and limited storage for buffer? Solar panels are absurdly cheap, and the world has a lot of equatorial desert.

angiosperm 3y ago
Yes, we can, and will do. Solar is so cheap that 4x overbuild is still cheaper than nukes, and cost is still plummeting.

asylteltine 3y ago

Nuclear is the way forward. It’s a damn shame hippies stopped us from leveraging it. We literally wouldn’t have climate change if we kept increasing nuclear power plants in the 70s. It’s just a no brainer. Solar and wind are great but the amount of power they generate may as well be 0 compared to nuclear.

Faaak 3y ago
> We literally wouldn’t have climate change if we kept increasing nuclear power plants in the 70s I highly doubt this
- asylteltine 3y ago
  Methane and coal is the largest driver of climate change
simplyluke 3y ago
> Solar and wind are great but the amount of power they generate may as well be 0 compared to nuclear. This is very untrue both measured in absolute numbers, and in cost/kwh. Nuclear is 2x solar and wind, both of which are decreasing in cost rapidly YoY. https://www.statista.com/statistics/194327/estimated-levelized-capital-cost-of-energy-generation-in-the-us/ https://www.statista.com/statistics/194327/estimated-leveliz...

ken47 3y ago

You're comparing a one-time-use resource in U235 vs. the land required for a solar plant, which will last indefinitely for all intents and purposes. Adding the "in a day" constraint is quite misleading in your comment when that is not the long-term limiting factor. Let's not forget that the externalities of nuclear power are generally much more costly than solar / wind.

nojvek 3y ago

We need to move away from coal as soon as we can. Coal is worst CO2 pollutant and not that energy dense. Move to a mixture of wind, solar, geothermal, hydro, nuclear - whatever makes sense. When the last coal powered plant is shut off in US, we should celebrate that as a day off for everyone.

AtlasBarfed 3y ago

Have you seen the Lazard lcoe numbers? Nukes are 6x more expensive than wind solar. And wind and especially solar have more economies of scale and materials research to make them even cheaper. This comes from a LFTR fanboy. Boy howdy do I wish economical nuclear existed. But 6x as expensive? That ain't all red tape. I think of course that LFTR has a path to cheaper nuclear with breeding and near waste elimination, full fuel use, safety, and scalability. But I don't think it will ever beat solar, especially once mature multifunction silicon perovskite cells or something like that and salt water batteries develop. I hope to be proven wrong.nyclest power is so cool.