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It is correct that batteries are the most expensive storage. One corrolary is that other storage is cheaper. Another is that other methods will be used instead.

by ncmncm 4y ago

It is correct that batteries are the most expensive storage. One corrolary is that other storage is cheaper. Another is that other methods will be used instead. Storage is an integral part of a renewable-powered grid. It is figured into all the cost analyses. Insisting otherwise is promoting known falsehoods. Lying is unwelcome here.

DennisP 4y ago
Hence my second paragraph. The only other major option is using pumped hydro for storage, but not every region has the geography for it.
- ncmncm 4y ago
  Pumped hydro is very far from the only alternative to batteries. But you have been told that before, too.
  - DennisP 4y ago
    "Hence my second paragraph" which was this: > At this point someone usually says "we don't need batteries for long-term storage, we can just make hydrogen and burn it later" but then oops, you're back to using a turbine. There are various experimental options too but I don't think any have deployed at scale, so their costs are uncertain. And some of them, like thermal storage, will still use a turbine.
    - ncmncm 4y ago
      Turbines cost less to operate part-time than full-time. One operated 4 hours / day, or one day / week, costs a lot less than one run continuously.
      - DennisP 4y ago
        I'm gonna need a source on that. It seems to me that turbine cost is mainly capital cost, and if you're not running it continuously then your cost per kWh is higher. After all, that's the argument you renewables folks make when you say nuclear plants can't load-follow economically. So tell me why a turbine run intermittently is cheaper, and prove it with a source.
        ncmncm 4y ago
        Allow me to invite you to look up steam turbine overhaul cost and frequency. Do mothballed turbines need frequent overhauls? Or will they need overhauls after N hours' use at intensity Y, or after M > N operated at intensity X < Y? Steam turbines are a substantial fraction of nuke operating cost, but far from the only substantial cost.
        DennisP 4y ago
        An idle turbine also isn't earning revenue. I haven't found specific numbers on steam turbines, but this pdf says a gas turbine's maintenance cost over 30 years is 3 to 4 times the capital cost: https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR.pdf https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR... So taking the worst case, capital plus maintenance for a continually-running turbine is 5X its capital cost, to get 30 years of power output. For each year of power, the total cost is 5/30 or 1/6 of the capital cost. Now lets take your 4 hours/day example. That's 1/6 as much running time, so only 5 total years of power output. It's also 1/6 as much maintenance cost, so maintenance is 4/6 of the capital cost, for a 30-year total cost of 1.66 times capital cost. Total cost per year of power is 1.66/5 = 1/3 of the capital cost. That puts the cost per kWh for energy storage at double the cost of the continuously-run turbine.
        Schroedingersat 4y ago
        That's tolerable compared to fission. You could model it roughly as adding the capex cost of half a turbine or so and x% of uptimes to your solar/wind capacity. Lifetime would also be longer but anything after 2060 or so is largely irrelevent for slowing climate change so we'll ignore it. IIRC O&M + Capex for a CCGT is about $20/MWh and fuel is around $30 which would put the capital around $5 and we don't expect to operate it for long as it's a backup. So the generator should cost us <$10 per MWh of solar + wind we use (with the majority being used directly or via batteries/hydro). Green fuel will cost about 2x the renewable energy with capex/O&M on the same order as the turbine or maybe a bit lower (ammonia electrolyzers are estimated about $1000/kw with current tech but you'd only need to put half or less of your peak capacity through it. Additionally they will run most of the time producing fuel if the target is using the fuel as the last resort backup). With projected solar + wind costs around $20/MWh using chemical storage for winter would then have a total cost of $60/MWh for energy that has been stored as ammonia and $40 for energy that has not in a somewhat pessimistic ballpark with price dominated by fuel generation. On par with some current full time gas, but at the upper end. Far less than fission if we use the same 'joules before 2060' constraint, but enough to cause difficulty building out new gas turbines if we don't presently have enough. Fusion isn't really in the running as a steam turbine is much more expensive than a gas one so we're getting close to parity with the renewable + battery + gas turbine just from the steam turbine step.

by ncmncm 4y ago

DennisP 4y ago

Hence my second paragraph. The only other major option is using pumped hydro for storage, but not every region has the geography for it.

ncmncm 4y ago
Pumped hydro is very far from the only alternative to batteries. But you have been told that before, too.
- DennisP 4y ago
  "Hence my second paragraph" which was this: > At this point someone usually says "we don't need batteries for long-term storage, we can just make hydrogen and burn it later" but then oops, you're back to using a turbine. There are various experimental options too but I don't think any have deployed at scale, so their costs are uncertain. And some of them, like thermal storage, will still use a turbine.
  - ncmncm 4y ago
    Turbines cost less to operate part-time than full-time. One operated 4 hours / day, or one day / week, costs a lot less than one run continuously.
    - DennisP 4y ago
      I'm gonna need a source on that. It seems to me that turbine cost is mainly capital cost, and if you're not running it continuously then your cost per kWh is higher. After all, that's the argument you renewables folks make when you say nuclear plants can't load-follow economically. So tell me why a turbine run intermittently is cheaper, and prove it with a source.
      - ncmncm 4y ago
        Allow me to invite you to look up steam turbine overhaul cost and frequency. Do mothballed turbines need frequent overhauls? Or will they need overhauls after N hours' use at intensity Y, or after M > N operated at intensity X < Y? Steam turbines are a substantial fraction of nuke operating cost, but far from the only substantial cost.
        DennisP 4y ago
        An idle turbine also isn't earning revenue. I haven't found specific numbers on steam turbines, but this pdf says a gas turbine's maintenance cost over 30 years is 3 to 4 times the capital cost: https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR.pdf https://www.gasturbine.org/papers/GTA%20Comments%20on%20RMRR... So taking the worst case, capital plus maintenance for a continually-running turbine is 5X its capital cost, to get 30 years of power output. For each year of power, the total cost is 5/30 or 1/6 of the capital cost. Now lets take your 4 hours/day example. That's 1/6 as much running time, so only 5 total years of power output. It's also 1/6 as much maintenance cost, so maintenance is 4/6 of the capital cost, for a 30-year total cost of 1.66 times capital cost. Total cost per year of power is 1.66/5 = 1/3 of the capital cost. That puts the cost per kWh for energy storage at double the cost of the continuously-run turbine.
        Schroedingersat 4y ago
        That's tolerable compared to fission. You could model it roughly as adding the capex cost of half a turbine or so and x% of uptimes to your solar/wind capacity. Lifetime would also be longer but anything after 2060 or so is largely irrelevent for slowing climate change so we'll ignore it. IIRC O&M + Capex for a CCGT is about $20/MWh and fuel is around $30 which would put the capital around $5 and we don't expect to operate it for long as it's a backup. So the generator should cost us <$10 per MWh of solar + wind we use (with the majority being used directly or via batteries/hydro). Green fuel will cost about 2x the renewable energy with capex/O&M on the same order as the turbine or maybe a bit lower (ammonia electrolyzers are estimated about $1000/kw with current tech but you'd only need to put half or less of your peak capacity through it. Additionally they will run most of the time producing fuel if the target is using the fuel as the last resort backup). With projected solar + wind costs around $20/MWh using chemical storage for winter would then have a total cost of $60/MWh for energy that has been stored as ammonia and $40 for energy that has not in a somewhat pessimistic ballpark with price dominated by fuel generation. On par with some current full time gas, but at the upper end. Far less than fission if we use the same 'joules before 2060' constraint, but enough to cause difficulty building out new gas turbines if we don't presently have enough. Fusion isn't really in the running as a steam turbine is much more expensive than a gas one so we're getting close to parity with the renewable + battery + gas turbine just from the steam turbine step.