5 ms·

> 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 arou

by 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.
- surfaceofthesun 3y ago
  Using Solar Star as another datapoint [1]. 579 MWac x 32.8% capacity factor ≈ 190. I found mention of a bond issuance and someone purchasing the project here [2]. If it’s $1b, then it’s $5.26. If $2b then $10.53. So they’re in the same ballpark. But one type of plant runs 20-30 years and the other for 50-80 years @ 90% capacity factor. The CANDU reactors are especially cool in that they can use natural uranium and refueled without a shutdown [3]. —- [1] - https://en.m.wikipedia.org/wiki/Solar_Star https://en.m.wikipedia.org/wiki/Solar_Star [2] - https://www.sustainablebusiness.com/2013/06/1-billion-bond-offering-completed-for-world39s-largest-solar-project-51678/ https://www.sustainablebusiness.com/2013/06/1-billion-bond-o... [3] - https://energyeducation.ca/encyclopedia/On-line_refueling_of_nuclear_power_plants https://energyeducation.ca/encyclopedia/On-line_refueling_of...
- hef19898 3y ago
  One thing you didn't include: Opex, a solar farm is pretty low maintenance and requires zero fuel. A NPP is the opposite.
  - apatheticonion 3y ago
    That's fair, I wonder if there are numbers on running costs. I'm certain nuclear running costs would dwarf solar - I think solar just needs fresh water, cleaning and hardware maintenance (replacing inverters, and such). Would be interesting to work the running costs into the "$ per realized W" calculation. I'd also like to see how battery-backed solar compares. I assume the objective would be to solve the intermittency issue, but I am hopeful it would increase the capacity factor as well. Another thing that's interesting to consider is multi-purpose energy utilization you get with nuclear - like desalination and hydrogen generation - though the latter is uneconomical because hydrogen produced from fossil fuels is much cheaper.
    - hef19898 3y ago
      Had to dig in my comments, but there you go: https://news.ycombinator.com/item?id=38303819 https://news.ycombinator.com/item?id=38303819 Self citing: Better not use biased opinion pieces, when there numbers from government sources (US, but eho cares): LCOE (total, incl. CAPEX, in USD per MWh): coal 82.6, combined cycle 39.9, advanced nuclear 81.7, geothermal 37.6, biomass 90.1, onshore wind 40, offshore wind (that one was a surprise, since offshore wind should be quite cheap, mainly driven by capital cost of 104 USD per MWh) 105, solar 33.8, solar hybrid 49 and hydro 64. Variable cost (same as above): coal 23.7, combined cycle 27.7, adv. nuclear 10.3, geothermal 1.2, biomass 30, onshore wind 0, offshore wind 0, solar 0, solar hybrid 0, hydro 4.1 All number from here: https://www.eia.gov/outlooks/aeo/pdf/electricity_generation https://www.eia.gov/outlooks/aeo/pdf/electricity_generation...., page 9.
deleted 3y ago
[deleted]
mixdup 3y ago
>That's missing the huge and expensive nuclear power plant around that kilogram of uranium. Whereas I think you are missing the huge and expensive battery array for solar to be useful outside of peak times? And the fact that the best sites for solar are far away from the transmission network?
pfdietz 3y ago
You dropped a decimal point. The 1 kg of sunlight at 15% efficiency produces 13.5 petajoules of electricity.

by est31 3y ago

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.

surfaceofthesun 3y ago
Using Solar Star as another datapoint [1]. 579 MWac x 32.8% capacity factor ≈ 190. I found mention of a bond issuance and someone purchasing the project here [2]. If it’s $1b, then it’s $5.26. If $2b then $10.53. So they’re in the same ballpark. But one type of plant runs 20-30 years and the other for 50-80 years @ 90% capacity factor. The CANDU reactors are especially cool in that they can use natural uranium and refueled without a shutdown [3]. —- [1] - https://en.m.wikipedia.org/wiki/Solar_Star https://en.m.wikipedia.org/wiki/Solar_Star [2] - https://www.sustainablebusiness.com/2013/06/1-billion-bond-offering-completed-for-world39s-largest-solar-project-51678/ https://www.sustainablebusiness.com/2013/06/1-billion-bond-o... [3] - https://energyeducation.ca/encyclopedia/On-line_refueling_of_nuclear_power_plants https://energyeducation.ca/encyclopedia/On-line_refueling_of...
hef19898 3y ago
One thing you didn't include: Opex, a solar farm is pretty low maintenance and requires zero fuel. A NPP is the opposite.
- apatheticonion 3y ago
  That's fair, I wonder if there are numbers on running costs. I'm certain nuclear running costs would dwarf solar - I think solar just needs fresh water, cleaning and hardware maintenance (replacing inverters, and such). Would be interesting to work the running costs into the "$ per realized W" calculation. I'd also like to see how battery-backed solar compares. I assume the objective would be to solve the intermittency issue, but I am hopeful it would increase the capacity factor as well. Another thing that's interesting to consider is multi-purpose energy utilization you get with nuclear - like desalination and hydrogen generation - though the latter is uneconomical because hydrogen produced from fossil fuels is much cheaper.
  - hef19898 3y ago
    Had to dig in my comments, but there you go: https://news.ycombinator.com/item?id=38303819 https://news.ycombinator.com/item?id=38303819 Self citing: Better not use biased opinion pieces, when there numbers from government sources (US, but eho cares): LCOE (total, incl. CAPEX, in USD per MWh): coal 82.6, combined cycle 39.9, advanced nuclear 81.7, geothermal 37.6, biomass 90.1, onshore wind 40, offshore wind (that one was a surprise, since offshore wind should be quite cheap, mainly driven by capital cost of 104 USD per MWh) 105, solar 33.8, solar hybrid 49 and hydro 64. Variable cost (same as above): coal 23.7, combined cycle 27.7, adv. nuclear 10.3, geothermal 1.2, biomass 30, onshore wind 0, offshore wind 0, solar 0, solar hybrid 0, hydro 4.1 All number from here: https://www.eia.gov/outlooks/aeo/pdf/electricity_generation https://www.eia.gov/outlooks/aeo/pdf/electricity_generation...., page 9.

deleted 3y ago

[deleted]

mixdup 3y ago

>That's missing the huge and expensive nuclear power plant around that kilogram of uranium. Whereas I think you are missing the huge and expensive battery array for solar to be useful outside of peak times? And the fact that the best sites for solar are far away from the transmission network?

pfdietz 3y ago

You dropped a decimal point. The 1 kg of sunlight at 15% efficiency produces 13.5 petajoules of electricity.