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> Developers and power plant owners plan to significantly increase utility-scale battery storage capacity in the United States over the next three years, reachi

by crmd 4y ago

> Developers and power plant owners plan to significantly increase utility-scale battery storage capacity in the United States over the next three years, reaching 30.0 gigawatts (GW) by the end of 2025 Can someone explain how/why they are measuring storage capacity in watts?

jupp0r 4y ago
I came here to complain about the same thing. Don't they have anybody who can proofread these diagrams and texts? For some reason, electric power related articles are super prone to people getting units wrong.
digitalscribe 4y ago
Because this is for utility companies where the value of the rate of discharge might be even more important than the energy capacity? A quick look at their site shows "battery power capacity" is measured in watts, whereas "battery energy capacity" is measured in watt-hours. https://www.eia.gov/todayinenergy/detail.php?id=51798 https://www.eia.gov/todayinenergy/detail.php?id=51798
bamboozled 4y ago
What should it be measured in?
- jdsully 4y ago
  watt/hours is the typical measurement. Raw wattage is insufficient without a time component.
  - rightbyte 4y ago
    Wh, not W/h. W/h is a change in power. "Scotty, increase engine power by 1 gigawatt per hour!"
    - epistasis 4y ago
      And for a lot the initial lithium ion storage on the grid, which was used for frequency regulation, the W/h or ability to respond to powe change, was a far far more important characteristic of the batteries than the Wh.
kevinventullo 4y ago
This doc has more information: https://www.nrel.gov/docs/fy19osti/74426.pdf https://www.nrel.gov/docs/fy19osti/74426.pdf They’re talking about the power capacity, which is the maximum instantaneous rate of discharge as measured in kW, as opposed to the energy capacity which is measured in kWh. From what I can glean, it appears that for many applications, the power capacity is actually the more important number.
- lazide 4y ago
  It is a bit weird, and seems to come from a history of fossil fuel, nuclear, and/or hydropower where the total capacity is always some (very large) multiple of the instantaneous power level. With storage currently just supplementing other power sources as renewables aren’t the majority (or all) of available capacity to provide grid stability, it makes sense I guess. None of these battery storage systems need to provide meaningful load beyond a few hours now. Hard to imagine that won’t change at some point though, probably soonish?
  - epistasis 4y ago
    "Long duration" storage doesn't have many economic use cases right now, unless the cost is a tiny tiny fraction of current storage costs. There are many startups developing tech for this, and one with the most hype (and the one I'm most excited about) is Form Energy, which is using iron-air chemistry. Nonetheless, I do not expect to see a significant market demand for such batteries until into the 2030s; it takes a really high level of renewables penetration before it makes sense to start having long duration storage at the moment. If there is a large need for it, I would expect that a lot of existing installations will be upgraded with longer duration, so that the same inverters and grid connection can be reused. New connections to the grid are becoming quite difficult to build on a reasonable time scale, and there's starting to be significant economic rent from just the permitting and connection stages.
    - lazide 4y ago
      I agree, thanks for writing that up. Do you think it will require the phase out of things like Natural Gas peaker plants to make longer term storage more worthwhile? Off grid, the most economic setup right now in California is essentially solar + batteries with battery storage sized up to about a day/24 hrs of load, with a propane fueled generator + propane backup heaters for ‘emergencies’ like long winter storms. Generators get exercised regularly to ensure functionality, but otherwise don’t get run unless needed, which is rare. Maybe 16-24 hrs a season. They also charge the batteries when their full load isn’t needed elsewhere, which cuts run time. Natural Gas would of course be the replacement for propane in a grid situation, where it was available. The paperwork and permitting in general is a sign of the future for sure. sigh
bee_rider 4y ago
I believe they mean: (Battery storage) capacity not Battery (storage capacity). That is, they are talking about power capacity (power is probably implied by default), which is provided by a type of device. The type of device is “battery storage.”

by crmd 4y ago

jupp0r 4y ago

I came here to complain about the same thing. Don't they have anybody who can proofread these diagrams and texts? For some reason, electric power related articles are super prone to people getting units wrong.

digitalscribe 4y ago

Because this is for utility companies where the value of the rate of discharge might be even more important than the energy capacity? A quick look at their site shows "battery power capacity" is measured in watts, whereas "battery energy capacity" is measured in watt-hours. https://www.eia.gov/todayinenergy/detail.php?id=51798 https://www.eia.gov/todayinenergy/detail.php?id=51798

bamboozled 4y ago

What should it be measured in?

jdsully 4y ago
watt/hours is the typical measurement. Raw wattage is insufficient without a time component.
- rightbyte 4y ago
  Wh, not W/h. W/h is a change in power. "Scotty, increase engine power by 1 gigawatt per hour!"
  - epistasis 4y ago
    And for a lot the initial lithium ion storage on the grid, which was used for frequency regulation, the W/h or ability to respond to powe change, was a far far more important characteristic of the batteries than the Wh.

kevinventullo 4y ago

This doc has more information: https://www.nrel.gov/docs/fy19osti/74426.pdf https://www.nrel.gov/docs/fy19osti/74426.pdf They’re talking about the power capacity, which is the maximum instantaneous rate of discharge as measured in kW, as opposed to the energy capacity which is measured in kWh. From what I can glean, it appears that for many applications, the power capacity is actually the more important number.

lazide 4y ago
It is a bit weird, and seems to come from a history of fossil fuel, nuclear, and/or hydropower where the total capacity is always some (very large) multiple of the instantaneous power level. With storage currently just supplementing other power sources as renewables aren’t the majority (or all) of available capacity to provide grid stability, it makes sense I guess. None of these battery storage systems need to provide meaningful load beyond a few hours now. Hard to imagine that won’t change at some point though, probably soonish?
- epistasis 4y ago
  "Long duration" storage doesn't have many economic use cases right now, unless the cost is a tiny tiny fraction of current storage costs. There are many startups developing tech for this, and one with the most hype (and the one I'm most excited about) is Form Energy, which is using iron-air chemistry. Nonetheless, I do not expect to see a significant market demand for such batteries until into the 2030s; it takes a really high level of renewables penetration before it makes sense to start having long duration storage at the moment. If there is a large need for it, I would expect that a lot of existing installations will be upgraded with longer duration, so that the same inverters and grid connection can be reused. New connections to the grid are becoming quite difficult to build on a reasonable time scale, and there's starting to be significant economic rent from just the permitting and connection stages.
  - lazide 4y ago
    I agree, thanks for writing that up. Do you think it will require the phase out of things like Natural Gas peaker plants to make longer term storage more worthwhile? Off grid, the most economic setup right now in California is essentially solar + batteries with battery storage sized up to about a day/24 hrs of load, with a propane fueled generator + propane backup heaters for ‘emergencies’ like long winter storms. Generators get exercised regularly to ensure functionality, but otherwise don’t get run unless needed, which is rare. Maybe 16-24 hrs a season. They also charge the batteries when their full load isn’t needed elsewhere, which cuts run time. Natural Gas would of course be the replacement for propane in a grid situation, where it was available. The paperwork and permitting in general is a sign of the future for sure. sigh

bee_rider 4y ago

I believe they mean: (Battery storage) capacity not Battery (storage capacity). That is, they are talking about power capacity (power is probably implied by default), which is provided by a type of device. The type of device is “battery storage.”