4 ms·

I see a lot of solar+storage quotes that don't bother saying how much storage. Usually it's four hours of storage at most. That's enough to smooth out the duck

I see a lot of solar+storage quotes that don't bother saying how much storage. Usually it's four hours of storage at most. That's enough to smooth out the duck curve and get your daytime demand covered, but not enough to get through a windless night. Building enough nuclear for baseload demand, and enough solar+storage for the extra daytime demand, seems ideal to me until we get much cheaper scalable storage.

seiferteric 4y ago
It's a great point. Even in my spot in northern California this winter, it's been so cloudy this year, I can't imaging an all solar+storage grid would have worked out well this year. In this case having electricity that costs 45% more when it's cloudy is a lot better than none at all. Actually this gave me an idea, it would be really neat to have an comprehensive simulator of power grids that incorporated weather, demand spikes etc. to play around with different energy source mix to get an idea of what actually works and when it fails as well as total cost, environmental impact etc.
- mikeyouse 4y ago
  > Even in my spot in northern California this winter, it's been so cloudy this year, I can't imaging an all solar+storage grid would have worked out well this year. The electricity demand in the winter is much lower than the summer demand, especially in California due to residential AC. > Actually this gave me an idea, it would be really neat to have an comprehensive simulator of power grids that incorporated weather, demand spikes etc. to play around with different energy source mix to get an idea of what actually works and when it fails as well as total cost, environmental impact etc. There's a gentleman in Australia who does ~this for their market -- 5 hours of storage is enough to get to a 99% renewable grid there; https://twitter.com/DavidOsmond8/status/1640959088887730176 https://twitter.com/DavidOsmond8/status/1640959088887730176
  - seiferteric 4y ago
    With heat pumps coming online and gas being phased out that might not be true for very long. Also is 99% even close to good enough? That would be like 4 days a year without power right?
    - Godel_unicode 4y ago
      And induction cooktops, and home charging BEVs overnight…
      - seiferteric 4y ago
        my back of the envelope calculation based on current human energy usage and battery production, it would take more than 150 years to manufacture 5 hours storage capacity. Of course manufacturing capacity is increasing and efficiency improves with electrification, but so is energy consumption, plus you have to factor in battery replacements during that time... Ya its going be tough to do that.
        syntheweave 4y ago
        It's a more complex calculation than that because not all the energy storage is going to use battery electric. Pumped storage hydro is often pointed to as one option for mass quantities over a long durations, and somewhat more esoteric stuff like low-friction flywheels comes up for "capacitor" type loads where what's needed is a cycle of a few minutes. The advantage of the batteries is specifically in power density, which makes them suited for mobility and consumer convenience. But the more you get into seriously optimizing electrical storage for scale, the less it's going to be about one specific mode.
        mikeyouse 4y ago
        No offense to your envelope, but that feels like a silly assumption. We produced ~15GWH of batteries in 2010 and now that takes us something like 3 weeks? Planned capacity additions will make that a daily production amount by 2030, and each subsequent cell is cheaper than the one before. This also assumes Li Ion as the only game in town. Plenty of other more likely options (flow batteries, hydro, etc) are feasible on a 15-year horizon. 5 Hours of electricity is something like 13 TWh, so if we get to 5,500 GWh annual production by 2030, it would take ~2.5 years to provide 5 hours of global electricity storage. Handicap it all and double the electricity requirement and halve the annual production figures and it's still only 10 years' capacity to go to a 99% carbon-free grid.
  - TaylorAlexander 4y ago
    > The electricity demand in the winter is much lower than the summer demand, especially in California due to residential AC. My mom's house doesn't need A/C but it does need a lot of heat in the winter. We looked at moving her to solar/battery and an electric heat pump instead of her gas furnace. With even a tiny bit of trees nearby and otherwise pretty good exposure we were told it was going to be hard to make it worth it. Her demand in the winter would be pretty high.
    - PaulDavisThe1st 4y ago
      We generate 3x our needs in summer; 1/3 of our needs in winter, when we are running electric air source heat pumps at 6000' in northern NM. If we had a passivhaus-level home, I think it could be possible to satisfy the winter heat requirements with the solar we have, but not with anything less (and even then, it would be challenging).
      - TaylorAlexander 4y ago
        Interesting, I appreciate the information. What is the nominal capacity of your solar array?
        PaulDavisThe1st 4y ago
        6.7kW We typically generate 800kW - 1300kW per month (more in the summer). Our panels are angled at 30 degrees to slightly preference winter generation.
        TaylorAlexander 4y ago
        Great, thanks!
tcfhgj 4y ago
there aren't windless night's when you increase the area you are looking at
- DennisP 4y ago
  Sure, but there are windless nights over fairly large areas sometimes, and the US is pretty bad at building long-distance transmission. Some projects have languished for decades.
  - Tade0 4y ago
    There also really aren't windless nights 220m above ground level, or where the hub of a Haliade-X 14MW turbine sits - especially offshore.
cagenut 4y ago
you misunderstand how the "+4" storage design works for solar. a 1MW solar plant nameplate capacity will only produce 1M for an hour or two a day, the hours before and after that peak will be some fraction, the sum total off the area under the curve works out to between 3 and 5 hours depending on latitude and weather[1]. so when you design a utility solar system with "+4" storage, what you're really doing is creating a "one days worth of full production" buffer. that can be used to run the output at a fixed rate while the buffer builds and empties every day (its never that simple but thats the basic principle). for example a 100MW farm with 400MWH of storage can in the simplest sense produce 16MW constantly (all through the day and night). in practice there's plenty of other stuff on most grids so they don't do a full battery cycle every night, but rather use the buffer to be able to meet day ahead and dispatchability contracts for a very cloudy day or a lightly cloudy week. now don't get me wrong, obviously that still doesn't put it in the same reliability category as nuclear, but it closes like 80% of the gap in practice. its not better, but it is clearly on track to be 'good enough'. [1] https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018-usa-scale-01.jpg https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018...
Ekaros 4y ago
Anyone who don't include cost of seasonal storage in renewable pricing is malicious or stupid. That is what really matters, not the spot price. We use power in winters and nights. Then again people freezing to death is certainly effective way to lower co2 emissions, maybe this is their hidden agenda.
tomatocracy 4y ago
Most battery storage being built (at least in the UK, which is the market I'm most aware of) isn't even 4 hours - it's generally 1 hour, moving towards 2. A lot was built to target the "dynamic containment" (frequency response) market primarily and not the daily peak/off-peak cycle.

seiferteric 4y ago

It's a great point. Even in my spot in northern California this winter, it's been so cloudy this year, I can't imaging an all solar+storage grid would have worked out well this year. In this case having electricity that costs 45% more when it's cloudy is a lot better than none at all. Actually this gave me an idea, it would be really neat to have an comprehensive simulator of power grids that incorporated weather, demand spikes etc. to play around with different energy source mix to get an idea of what actually works and when it fails as well as total cost, environmental impact etc.

mikeyouse 4y ago
> Even in my spot in northern California this winter, it's been so cloudy this year, I can't imaging an all solar+storage grid would have worked out well this year. The electricity demand in the winter is much lower than the summer demand, especially in California due to residential AC. > Actually this gave me an idea, it would be really neat to have an comprehensive simulator of power grids that incorporated weather, demand spikes etc. to play around with different energy source mix to get an idea of what actually works and when it fails as well as total cost, environmental impact etc. There's a gentleman in Australia who does ~this for their market -- 5 hours of storage is enough to get to a 99% renewable grid there; https://twitter.com/DavidOsmond8/status/1640959088887730176 https://twitter.com/DavidOsmond8/status/1640959088887730176
- seiferteric 4y ago
  With heat pumps coming online and gas being phased out that might not be true for very long. Also is 99% even close to good enough? That would be like 4 days a year without power right?
  - Godel_unicode 4y ago
    And induction cooktops, and home charging BEVs overnight…
    - seiferteric 4y ago
      my back of the envelope calculation based on current human energy usage and battery production, it would take more than 150 years to manufacture 5 hours storage capacity. Of course manufacturing capacity is increasing and efficiency improves with electrification, but so is energy consumption, plus you have to factor in battery replacements during that time... Ya its going be tough to do that.
      - syntheweave 4y ago
        It's a more complex calculation than that because not all the energy storage is going to use battery electric. Pumped storage hydro is often pointed to as one option for mass quantities over a long durations, and somewhat more esoteric stuff like low-friction flywheels comes up for "capacitor" type loads where what's needed is a cycle of a few minutes. The advantage of the batteries is specifically in power density, which makes them suited for mobility and consumer convenience. But the more you get into seriously optimizing electrical storage for scale, the less it's going to be about one specific mode.
      - mikeyouse 4y ago
        No offense to your envelope, but that feels like a silly assumption. We produced ~15GWH of batteries in 2010 and now that takes us something like 3 weeks? Planned capacity additions will make that a daily production amount by 2030, and each subsequent cell is cheaper than the one before. This also assumes Li Ion as the only game in town. Plenty of other more likely options (flow batteries, hydro, etc) are feasible on a 15-year horizon. 5 Hours of electricity is something like 13 TWh, so if we get to 5,500 GWh annual production by 2030, it would take ~2.5 years to provide 5 hours of global electricity storage. Handicap it all and double the electricity requirement and halve the annual production figures and it's still only 10 years' capacity to go to a 99% carbon-free grid.
- TaylorAlexander 4y ago
  > The electricity demand in the winter is much lower than the summer demand, especially in California due to residential AC. My mom's house doesn't need A/C but it does need a lot of heat in the winter. We looked at moving her to solar/battery and an electric heat pump instead of her gas furnace. With even a tiny bit of trees nearby and otherwise pretty good exposure we were told it was going to be hard to make it worth it. Her demand in the winter would be pretty high.
  - PaulDavisThe1st 4y ago
    We generate 3x our needs in summer; 1/3 of our needs in winter, when we are running electric air source heat pumps at 6000' in northern NM. If we had a passivhaus-level home, I think it could be possible to satisfy the winter heat requirements with the solar we have, but not with anything less (and even then, it would be challenging).
    - TaylorAlexander 4y ago
      Interesting, I appreciate the information. What is the nominal capacity of your solar array?
      - PaulDavisThe1st 4y ago
        6.7kW We typically generate 800kW - 1300kW per month (more in the summer). Our panels are angled at 30 degrees to slightly preference winter generation.
        TaylorAlexander 4y ago
        Great, thanks!

tcfhgj 4y ago

there aren't windless night's when you increase the area you are looking at

DennisP 4y ago
Sure, but there are windless nights over fairly large areas sometimes, and the US is pretty bad at building long-distance transmission. Some projects have languished for decades.
- Tade0 4y ago
  There also really aren't windless nights 220m above ground level, or where the hub of a Haliade-X 14MW turbine sits - especially offshore.

cagenut 4y ago

you misunderstand how the "+4" storage design works for solar. a 1MW solar plant nameplate capacity will only produce 1M for an hour or two a day, the hours before and after that peak will be some fraction, the sum total off the area under the curve works out to between 3 and 5 hours depending on latitude and weather[1]. so when you design a utility solar system with "+4" storage, what you're really doing is creating a "one days worth of full production" buffer. that can be used to run the output at a fixed rate while the buffer builds and empties every day (its never that simple but thats the basic principle). for example a 100MW farm with 400MWH of storage can in the simplest sense produce 16MW constantly (all through the day and night). in practice there's plenty of other stuff on most grids so they don't do a full battery cycle every night, but rather use the buffer to be able to meet day ahead and dispatchability contracts for a very cloudy day or a lightly cloudy week. now don't get me wrong, obviously that still doesn't put it in the same reliability category as nuclear, but it closes like 80% of the gap in practice. its not better, but it is clearly on track to be 'good enough'. [1] https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018-usa-scale-01.jpg https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018...

Ekaros 4y ago

Anyone who don't include cost of seasonal storage in renewable pricing is malicious or stupid. That is what really matters, not the spot price. We use power in winters and nights. Then again people freezing to death is certainly effective way to lower co2 emissions, maybe this is their hidden agenda.

tomatocracy 4y ago

Most battery storage being built (at least in the UK, which is the market I'm most aware of) isn't even 4 hours - it's generally 1 hour, moving towards 2. A lot was built to target the "dynamic containment" (frequency response) market primarily and not the daily peak/off-peak cycle.