3 ms·

Grid Storage is very expensive and right now only has a few hours of capacity. We would need weeks to really replace nuclear.

epistasis 6mo ago
Saying that grid storage "only has a few hours of capacity" is like saying that a nuclear power reactor "only has 1GW of power." You solve both issues by deploying more. And if you want a longer lithium ion battery installation without the additional power capacity, you can save a bit on inverters. Grid storage is cheap enough that Texas, a purely profit-driven grid is now overtaking California in the amount of battery storage deployed. 58GWh of new grid storage was added in 2025 alone, and the growth is still exponentialhttps://seia.org/news/united-states-installs-58-gwh-of-new-energy-storage-in-2025/ https://seia.org/news/united-states-installs-58-gwh-of-new-e...
- UltraSane 6mo ago
  All current grid storage will fully discharge in less than 4 hours at max watts. It is designed to level daily demand variability. To make a 4 hour battery last for a week at the same wattage would make it cost 42 times as much.
  - epistasis 6mo ago
    Yes, this is how the basic arithmetic works. What's your point? I see now that your original post had a fantastical claim that we need weeks of battery storage, which is a fantastical claim. In reality we will need variable amounts of battery but a "week long" battery is not supported by a single detailed grid study I have ever seen. When I have asked Pell to justify claims of "weeks long battery" the only justifications have been "I heard it from someone else", or napkin math that contains many errors, and in places where there are not errors choices are made to estimate an upper bound rather than a lower bound, indicating that the calculator doesn't understand how napkins math can be useful. And for super cheap infrequently used storage, here's a recent purchase at $33/kWh of a 30GWh battery by Google: https://news.ycombinator.com/item?id=47176841 https://news.ycombinator.com/item?id=47176841 I don't expect such batteries to be used much, despite being a fraction of the cost of current LFP batteries, because we really won't need much storage with such a low power:energy ratio.
    - UltraSane 6mo ago
      My point is that no one is building 1 week batteries because they would be incredibly expensive. To make sure we are on the same page are you envisioning a grid powered 100% by wind + solar + batteries?
      - epistasis 6mo ago
        People are building 100 hour (5 day) batteries because they are incredibly cheap, but they're not doing many of them because they're not needed. Don't forget existing hydro, new advanced geothermal, existing nuclear (until they all reach end of life), etc. etc. etc.
        UltraSane 6mo ago
        "People are building 100 hour (5 day) batteries" Please provide links.
        epistasis 6mo ago
        I did already, here https://news.ycombinator.com/item?id=47176841 https://news.ycombinator.com/item?id=47176841 Also, 5 was a typo, it should have been 4 of course! Form energy has been making a major splash for years, having first modeled out the grid case for this type of battery, and ensuring that all materials and battery chemistry allowed a potential route to success. It's iron-air.
tstrimple 6mo ago
Incredibly disingenuous for nuclear power proponents to state that grid storage is expensive. Your entire argument centers around the most expensive power generation available and one of the slowest to build.
- UltraSane 6mo ago
  Grid storage is very expensive which is why all grid scale batteries discharge in 4 hours or less at full output.
  - epistasis 6mo ago
    Grid batteries are mostly four hours duration because that's the natural charging and discharging rate for current chemistries, and there's no financial case to store energy for longer right now, as in there's no demand for long term storage at all. Four hours of storage is super profitable, eight hours is just unnecessary and nobody pays for it. Plus, referring to this in terms of "hours" isn't exactly the most informative reference, the more underlying characteristic of storage is if it's meant for daily cycling, meaning that it makes mine every single day from arbitrage, or if it's multi day which is not a super profitable form of arbitrage at the moment. Daily cycling makes a ton of sense with solar. Longer term cycles make more sense paired with wind.

epistasis 6mo ago

Saying that grid storage "only has a few hours of capacity" is like saying that a nuclear power reactor "only has 1GW of power." You solve both issues by deploying more. And if you want a longer lithium ion battery installation without the additional power capacity, you can save a bit on inverters. Grid storage is cheap enough that Texas, a purely profit-driven grid is now overtaking California in the amount of battery storage deployed. 58GWh of new grid storage was added in 2025 alone, and the growth is still exponentialhttps://seia.org/news/united-states-installs-58-gwh-of-new-energy-storage-in-2025/ https://seia.org/news/united-states-installs-58-gwh-of-new-e...

UltraSane 6mo ago
All current grid storage will fully discharge in less than 4 hours at max watts. It is designed to level daily demand variability. To make a 4 hour battery last for a week at the same wattage would make it cost 42 times as much.
- epistasis 6mo ago
  Yes, this is how the basic arithmetic works. What's your point? I see now that your original post had a fantastical claim that we need weeks of battery storage, which is a fantastical claim. In reality we will need variable amounts of battery but a "week long" battery is not supported by a single detailed grid study I have ever seen. When I have asked Pell to justify claims of "weeks long battery" the only justifications have been "I heard it from someone else", or napkin math that contains many errors, and in places where there are not errors choices are made to estimate an upper bound rather than a lower bound, indicating that the calculator doesn't understand how napkins math can be useful. And for super cheap infrequently used storage, here's a recent purchase at $33/kWh of a 30GWh battery by Google: https://news.ycombinator.com/item?id=47176841 https://news.ycombinator.com/item?id=47176841 I don't expect such batteries to be used much, despite being a fraction of the cost of current LFP batteries, because we really won't need much storage with such a low power:energy ratio.
  - UltraSane 6mo ago
    My point is that no one is building 1 week batteries because they would be incredibly expensive. To make sure we are on the same page are you envisioning a grid powered 100% by wind + solar + batteries?
    - epistasis 6mo ago
      People are building 100 hour (5 day) batteries because they are incredibly cheap, but they're not doing many of them because they're not needed. Don't forget existing hydro, new advanced geothermal, existing nuclear (until they all reach end of life), etc. etc. etc.
      - UltraSane 6mo ago
        "People are building 100 hour (5 day) batteries" Please provide links.
        epistasis 6mo ago
        I did already, here https://news.ycombinator.com/item?id=47176841 https://news.ycombinator.com/item?id=47176841 Also, 5 was a typo, it should have been 4 of course! Form energy has been making a major splash for years, having first modeled out the grid case for this type of battery, and ensuring that all materials and battery chemistry allowed a potential route to success. It's iron-air.

tstrimple 6mo ago

Incredibly disingenuous for nuclear power proponents to state that grid storage is expensive. Your entire argument centers around the most expensive power generation available and one of the slowest to build.

UltraSane 6mo ago
Grid storage is very expensive which is why all grid scale batteries discharge in 4 hours or less at full output.
- epistasis 6mo ago
  Grid batteries are mostly four hours duration because that's the natural charging and discharging rate for current chemistries, and there's no financial case to store energy for longer right now, as in there's no demand for long term storage at all. Four hours of storage is super profitable, eight hours is just unnecessary and nobody pays for it. Plus, referring to this in terms of "hours" isn't exactly the most informative reference, the more underlying characteristic of storage is if it's meant for daily cycling, meaning that it makes mine every single day from arbitrage, or if it's multi day which is not a super profitable form of arbitrage at the moment. Daily cycling makes a ton of sense with solar. Longer term cycles make more sense paired with wind.