4 ms·

They both provide non-dispatchable power. Renewables have a slight edge at moderate penetration with no storage because you can turn them off whenever you want

They both provide non-dispatchable power. Renewables have a slight edge at moderate penetration with no storage because you can turn them off whenever you want without incurring massive costs and solar output is biased towards peak time. Then there's hybrid PV-CSP which is available in about half of the world and is dispatchable. I guess you're probably right in that nuclear doesn't compete because hybrid CSP is vastly cheaper even in FOAK form and dispatchable power is superior.

HyperSane 4y ago
Nuclear is dispatchable.
- Schroedingersat 4y ago
  No it isn't. Ramping is slow and can't be done beyond 20% very often or you destroy your fuel and control rods Reducing output doesn't reduce costs, it increases them. This is the opposite of dispatchable. If you can only pay for your reactor by coercing people into buying daytime electricity for 20c/kWh rather than buying a solar panel that will pay for itself in 3 years then it's not dispatchable.
  - Manuel_D 4y ago
    You don't need to alter the thermal output of the reactor to modulate a nuclear plant's electrical output. You can more aggressively cool the reactor to reduce the energy delivered to the turbine. This isn't often done since it's essentially deliberately reducing the efficiency of the plant. > Ramping is slow and can't be done beyond 20% very often or you destroy your fuel and control rods 20% is all that's necessary to accommodate most load variations: https://www.eia.gov/todayinenergy/detail.php?id=42915 https://www.eia.gov/todayinenergy/detail.php?id=42915
    - Schroedingersat 4y ago
      That is also slow. Dispatchable generation ramps in tens of seconds and you don't pay $90-200/MWh for it when you're not using it.
      - Manuel_D 4y ago
        It's not slow: the turbine water is can be cooled more aggressively immediately, and will start reducing output with one circuit of the generation turbine. Also, modulation only needs to vary 20-30% over the span of entire days not of tens of seconds. And no, dispatchable generation does not ramp in 10s of seconds. Natural gas plants - the most popular peaking generation plant - still takes an hour to activate. But this isn't an issue because electricity use doesn't fluctuate by 20% in the matter of tens of seconds.
        Schroedingersat 4y ago
        Tell that to the power station engineers who have to watch for the ad breaks in British TV. And it's still not dispatchable if not using it costs you anyway.
        Manuel_D 4y ago
        > And it's still not dispatchable if not using it costs you anyway. No? This just plain wrong. A dispatchable source is a dispatchable source, regardless of any associated costs. And with nuclear there isn't even any direct cost with running the plant at a reduced capacity. There's only the opportunity cost of lost electricity sales, which would happen anyway because there isn't enough demand. If there's 100 GW of peak demand and 80 GW of minimum demand, building 100 GW of nuclear plants and reducing output during periods of non-consumption does not have any increase of costs.
        Schroedingersat 4y ago
        If there's noone to sell your $150/MWh electricity to because they took one look at the price and put a solar panel on their roof, then you're not selling $150/MWh electricity, you're selling $500/MWh electricity for the 20% of power they must buy. Then when they take a look at the new price, they go buy a battery. The only way to pay it off is a government enforced utility connection fee for a product nobody wants. The only way to sell it for $150/MWh is to underprovision or to build storage or to find dispatchable loads. Just like renewables.

HyperSane 4y ago

Nuclear is dispatchable.

Schroedingersat 4y ago
No it isn't. Ramping is slow and can't be done beyond 20% very often or you destroy your fuel and control rods Reducing output doesn't reduce costs, it increases them. This is the opposite of dispatchable. If you can only pay for your reactor by coercing people into buying daytime electricity for 20c/kWh rather than buying a solar panel that will pay for itself in 3 years then it's not dispatchable.
- Manuel_D 4y ago
  You don't need to alter the thermal output of the reactor to modulate a nuclear plant's electrical output. You can more aggressively cool the reactor to reduce the energy delivered to the turbine. This isn't often done since it's essentially deliberately reducing the efficiency of the plant. > Ramping is slow and can't be done beyond 20% very often or you destroy your fuel and control rods 20% is all that's necessary to accommodate most load variations: https://www.eia.gov/todayinenergy/detail.php?id=42915 https://www.eia.gov/todayinenergy/detail.php?id=42915
  - Schroedingersat 4y ago
    That is also slow. Dispatchable generation ramps in tens of seconds and you don't pay $90-200/MWh for it when you're not using it.
    - Manuel_D 4y ago
      It's not slow: the turbine water is can be cooled more aggressively immediately, and will start reducing output with one circuit of the generation turbine. Also, modulation only needs to vary 20-30% over the span of entire days not of tens of seconds. And no, dispatchable generation does not ramp in 10s of seconds. Natural gas plants - the most popular peaking generation plant - still takes an hour to activate. But this isn't an issue because electricity use doesn't fluctuate by 20% in the matter of tens of seconds.
      - Schroedingersat 4y ago
        Tell that to the power station engineers who have to watch for the ad breaks in British TV. And it's still not dispatchable if not using it costs you anyway.
        Manuel_D 4y ago
        > And it's still not dispatchable if not using it costs you anyway. No? This just plain wrong. A dispatchable source is a dispatchable source, regardless of any associated costs. And with nuclear there isn't even any direct cost with running the plant at a reduced capacity. There's only the opportunity cost of lost electricity sales, which would happen anyway because there isn't enough demand. If there's 100 GW of peak demand and 80 GW of minimum demand, building 100 GW of nuclear plants and reducing output during periods of non-consumption does not have any increase of costs.
        Schroedingersat 4y ago
        If there's noone to sell your $150/MWh electricity to because they took one look at the price and put a solar panel on their roof, then you're not selling $150/MWh electricity, you're selling $500/MWh electricity for the 20% of power they must buy. Then when they take a look at the new price, they go buy a battery. The only way to pay it off is a government enforced utility connection fee for a product nobody wants. The only way to sell it for $150/MWh is to underprovision or to build storage or to find dispatchable loads. Just like renewables.