3 ms·

I think this is an interesting development for smaller generating needs, maybe even personal, but: > Ammonia can also be burned in modified gas turbines, which

by R0b0t1 5y ago

I think this is an interesting development for smaller generating needs, maybe even personal, but: > Ammonia can also be burned in modified gas turbines, which IMO would be a great way to quickly displace natural gas in peaker plants, to enable higher renewables penetration w/o relying on fossil fuels to take up the slack. Nukes can operate as peaker plants. The feedback from the control rods is nearly instantaneous. It's just in some markets they must telegraph their moves and get approval, which can take ~4 hours or more. I bring up nukes because how are we going to make the ammonia? Nitrogen fixing reactions take loads of power. You could get it from nukes until we figure out higher capacity solar collection, but I don't know of anything else that would work well.

djsbs 5y ago
“ Nukes can operate as peaker plants. The feedback from the control rods is nearly instantaneous.” But the physical thermal stress from throttling it significantly shorten its lifespan. Throttling nukes is not a trivial task; I know one plant (Bruce?) doesn't even bother changing the reactor power, they just inject steam into the bay instead of putto g it through a turbine
- R0b0t1 5y ago
  Sounds like red tape or other stupidity. Ramping up very hot yes, but matching loads like you would with a gas plant no.
  - djsbs 5y ago
    Its a bit complicated. Disclaimer: Im not a nuke engineer, I just took some nuke classes and was surrounded by then for a while. New reactor designs promise to throttle, but I don’t know if any have been deployed. This is a bit more complicated than a gas turbine. With a gas turbine, you just inject more gas as needed to keep the turbine turning at a constant speed. The combustion chamber is a violently small part of the whole. The heat producing part of a reactor, by contrast, is massive. As a result you have thermal gradients, and these gradients are different at different power. They’re also larger at larger power. A large thermal gradient isn’t a huge problem by itself (engineers have been accounting for this since the steam engine). The problem is the change of gradient itself. As the gradient changes, the materials inside change shape and this causes large mechanical stresses. The situation is pretty much the same as when you turn off an ICE car: ever hear those ringing or popping sounds it makes? That is the various hot parts cooling and changing shape abruptly. The problem for a reactor is made worse because material selection is very difficult: you cant just pick any alloy that has good thermal expansion, or good fatigue characteristics. Every alloy must be from a very narrow set of isotopes (not elements!!) that are compatible with the reactor’s neutron environment (balance, distribution, energy spectrum, etc).
    - R0b0t1 5y ago
      I know all of the basic science behind this, but there exist old test reactors that can respond to loads quickly enough to act as peaker plants. Your information is either absolutely ancient or propaganda.
      - djsbs 5y ago
        A throttle-able test reactor can be as simple as a pool with no pressure vessel. There’s maybe 100 of those in univeristies throughout the US. Now commercialize it.
- inter_netuser 5y ago
  Does this vary with nuke's design? I'd expect some do better than others.
  - djsbs 5y ago
    See answer to other comment.
- WalterBright 5y ago
  Should put a bitcoin mine in the power plant to use the excess power.
lambdatronics 5y ago
>Nukes can operate as peaker plants. Not in an economical fashion, though. Because the fixed costs dominate the variable costs, the less often the plant operates, the more it needs to charge for electricity when it is running. Gas peaker plants work the opposite way: low capital cost, significant variable cost (price of gas). That's more suited to the role. >how are we going to make the ammonia? From surplus renewables at other times of the year. Part of the solution is going to be overbuilding renewables by some factor, maybe 1.5x, compared to the total annual electrical energy demand. Ammonia is basically a way to store that surplus on a seasonal timescale for backup generation, in a more cost-effective way than batteries. Plus, we also need ammonia for fertilizer, and maybe it will be used for transportation (shipping especially).
- R0b0t1 5y ago
  You're not getting it. You keep the plant on all the time. When you need to reduce power you insert the control rods. You lose some efficiency, but you do burn the fuel less fast as well; you're getting so much energy out of the nuclear fuel it's irrelevant. This is established science and reactor design, it's not new. What I learned from a friend who works in power is there's red tape constrains on doing power variation which is why they don't do it.

by R0b0t1 5y ago

djsbs 5y ago

“ Nukes can operate as peaker plants. The feedback from the control rods is nearly instantaneous.” But the physical thermal stress from throttling it significantly shorten its lifespan. Throttling nukes is not a trivial task; I know one plant (Bruce?) doesn't even bother changing the reactor power, they just inject steam into the bay instead of putto g it through a turbine

R0b0t1 5y ago
Sounds like red tape or other stupidity. Ramping up very hot yes, but matching loads like you would with a gas plant no.
- djsbs 5y ago
  Its a bit complicated. Disclaimer: Im not a nuke engineer, I just took some nuke classes and was surrounded by then for a while. New reactor designs promise to throttle, but I don’t know if any have been deployed. This is a bit more complicated than a gas turbine. With a gas turbine, you just inject more gas as needed to keep the turbine turning at a constant speed. The combustion chamber is a violently small part of the whole. The heat producing part of a reactor, by contrast, is massive. As a result you have thermal gradients, and these gradients are different at different power. They’re also larger at larger power. A large thermal gradient isn’t a huge problem by itself (engineers have been accounting for this since the steam engine). The problem is the change of gradient itself. As the gradient changes, the materials inside change shape and this causes large mechanical stresses. The situation is pretty much the same as when you turn off an ICE car: ever hear those ringing or popping sounds it makes? That is the various hot parts cooling and changing shape abruptly. The problem for a reactor is made worse because material selection is very difficult: you cant just pick any alloy that has good thermal expansion, or good fatigue characteristics. Every alloy must be from a very narrow set of isotopes (not elements!!) that are compatible with the reactor’s neutron environment (balance, distribution, energy spectrum, etc).
  - R0b0t1 5y ago
    I know all of the basic science behind this, but there exist old test reactors that can respond to loads quickly enough to act as peaker plants. Your information is either absolutely ancient or propaganda.
    - djsbs 5y ago
      A throttle-able test reactor can be as simple as a pool with no pressure vessel. There’s maybe 100 of those in univeristies throughout the US. Now commercialize it.
inter_netuser 5y ago
Does this vary with nuke's design? I'd expect some do better than others.
- djsbs 5y ago
  See answer to other comment.
WalterBright 5y ago
Should put a bitcoin mine in the power plant to use the excess power.

lambdatronics 5y ago

>Nukes can operate as peaker plants. Not in an economical fashion, though. Because the fixed costs dominate the variable costs, the less often the plant operates, the more it needs to charge for electricity when it is running. Gas peaker plants work the opposite way: low capital cost, significant variable cost (price of gas). That's more suited to the role. >how are we going to make the ammonia? From surplus renewables at other times of the year. Part of the solution is going to be overbuilding renewables by some factor, maybe 1.5x, compared to the total annual electrical energy demand. Ammonia is basically a way to store that surplus on a seasonal timescale for backup generation, in a more cost-effective way than batteries. Plus, we also need ammonia for fertilizer, and maybe it will be used for transportation (shipping especially).

R0b0t1 5y ago
You're not getting it. You keep the plant on all the time. When you need to reduce power you insert the control rods. You lose some efficiency, but you do burn the fuel less fast as well; you're getting so much energy out of the nuclear fuel it's irrelevant. This is established science and reactor design, it's not new. What I learned from a friend who works in power is there's red tape constrains on doing power variation which is why they don't do it.