8 ms·

The point is not about future price evolution, but the marginal price of storing 1h more, if you just need another tank it will be cheaper than having the same

by hokkos 5y ago

The point is not about future price evolution, but the marginal price of storing 1h more, if you just need another tank it will be cheaper than having the same energy in a battery, with the same system to store and destore the liquid air. Li-ion is not a good fit for long term storage.

CydeWeys 5y ago
This system is already 500 MWh (that's huge). How much better scaling do you think it's going to get beyond that?
- ncmncm 5y ago
  The expensive part is the 50MW bits. They can build out storage capacity cheaply, because it is just tankage.
  - Retric 5y ago
    But if you’re only inputting and extracting at 50MW then having more than 600MWh of storage means it takes longer than 24h to fully charge and discharge. If anything 500MWh of storage is already well into diminishing returns as daily storage makes money every day but long term storage has less frequent returns.
    - ncmncm 5y ago
      If every (normal) day you discharge less than you charge, you can build up a reserve for unusual events. When you get close to your storage limit, you can sell power from out of that reserve during periods of peak usage/price, when your solar array is running at capacity. So, more storage is better.
      - Retric 5y ago
        Depends on the market price. Storing for say 1 month means you get 12 payouts per year, storing it for 12 hours means you get 365 payouts per year. If your on average getting say 1c/kWh from the distance in values prices every day then your monthly sale needs to be at 30c/kWh to be worth it. Prices simply don’t rise that high every month making long term storage less valuable than daily storage. On top of this these things aren’t 100% efficient. Buying at 7c/kWh and selling at 8c/kWh is losing money if these are say 80% efficient. Which means you’re never going to profitably buy and sell throughout the day. Thus the 500MWh capacity will mean some long term storage.
        ClumsyPilot 5y ago
        If we are going to go full-renewable we will need storage that works over night, storage for cloudy days and for days without wind. A low wind situation can last a week for example. So we do need long-term storage and we will have to finance it so that when we need it, we can count on it
        Retric 5y ago
        First Hydro is already effectively long term storage. It’s fixed across a year, but releasing 5x as much as normal is fine as long as releases are scaled back to account for the discharge. Next solar and wind don’t correlate and solar output never hits zero on cloudy days. So, excess capacity always directly reduces the need for storage. Working out the ideal amount of excess capacity isn’t trivial, but unless storage costs tank dramatically something like 85+% on worst case days is likely viable. Which could then easily be covered by hydro.
        ncmncm 5y ago
        Sometimes hydro is inconveniently on the other side of two national borders, as here, where Paraguay is on the other side of Argentina. There are good reasons to stay on pleasant terms with Argentina and Paraguay, but avoiding blackouts is among the less-good reasons.

by hokkos 5y ago

CydeWeys 5y ago

This system is already 500 MWh (that's huge). How much better scaling do you think it's going to get beyond that?

ncmncm 5y ago
The expensive part is the 50MW bits. They can build out storage capacity cheaply, because it is just tankage.
- Retric 5y ago
  But if you’re only inputting and extracting at 50MW then having more than 600MWh of storage means it takes longer than 24h to fully charge and discharge. If anything 500MWh of storage is already well into diminishing returns as daily storage makes money every day but long term storage has less frequent returns.
  - ncmncm 5y ago
    If every (normal) day you discharge less than you charge, you can build up a reserve for unusual events. When you get close to your storage limit, you can sell power from out of that reserve during periods of peak usage/price, when your solar array is running at capacity. So, more storage is better.
    - Retric 5y ago
      Depends on the market price. Storing for say 1 month means you get 12 payouts per year, storing it for 12 hours means you get 365 payouts per year. If your on average getting say 1c/kWh from the distance in values prices every day then your monthly sale needs to be at 30c/kWh to be worth it. Prices simply don’t rise that high every month making long term storage less valuable than daily storage. On top of this these things aren’t 100% efficient. Buying at 7c/kWh and selling at 8c/kWh is losing money if these are say 80% efficient. Which means you’re never going to profitably buy and sell throughout the day. Thus the 500MWh capacity will mean some long term storage.
      - ClumsyPilot 5y ago
        If we are going to go full-renewable we will need storage that works over night, storage for cloudy days and for days without wind. A low wind situation can last a week for example. So we do need long-term storage and we will have to finance it so that when we need it, we can count on it
        Retric 5y ago
        First Hydro is already effectively long term storage. It’s fixed across a year, but releasing 5x as much as normal is fine as long as releases are scaled back to account for the discharge. Next solar and wind don’t correlate and solar output never hits zero on cloudy days. So, excess capacity always directly reduces the need for storage. Working out the ideal amount of excess capacity isn’t trivial, but unless storage costs tank dramatically something like 85+% on worst case days is likely viable. Which could then easily be covered by hydro.
        ncmncm 5y ago
        Sometimes hydro is inconveniently on the other side of two national borders, as here, where Paraguay is on the other side of Argentina. There are good reasons to stay on pleasant terms with Argentina and Paraguay, but avoiding blackouts is among the less-good reasons.