4 ms·

> By 2025, the world’s base of cumulative installed storage capacity will reach 52 GW, IHS Markit says, up from around 4 GW today. Last year, 1.3 GW of grid-con

> By 2025, the world’s base of cumulative installed storage capacity will reach 52 GW, IHS Markit says, up from around 4 GW today. Last year, 1.3 GW of grid-connected storage was deployed globally, and this rate is poised to accelerate to 4.7 GW a year by 2020, and 8.8 GW annually by 2025. GW is not a unity of energy storage capacity. It's a unit of power.

epistasis 9y ago
GW is, however, a characteristic of an energy storage system, and just a valid and important measurement as the amount of energy it stores.
- Gracana 9y ago
  The maximum output is interesting to know, but if you asked how much my car's fuel tank held and I told you "100mph," you'd be understandably confused.
  - epistasis 9y ago
    But we're not talking about cars, we're talking about the electrical grid. In the current stage of the grid and storage, storage capacity is used not for long duration transmission of energy, but shorter term filling in of power gaps. In the past few years that's been frequency regulation, and now the replacement of peaker plants, or instantaneous response when waiting the 10-15 minutes for a peaker plant to come online.
  - deleted 9y ago
    [deleted]
  - mulmen 9y ago
    A watt is a measure of power, not distance. The equivalent unit for a car would be horsepower. You could express the capacity of your fuel tank in horsepower hours. Since both are measurements of power and horsepower is defined in terms of watts you could even measure the capacity of your fuel tank in kilowatt hours. Similarly, you can define the output of your engine in kilowatts.
- ptero 9y ago
  Maximum discharge speed (which is one of the very few storage characteristics I can think of to be measured in GW) is pretty much irrelevant for storage systems. Add a few quick discharge capacitors that cost almost nothing and boom -- your max discharge speed shoots through the roof (but speed goes down for a very short time). Maybe sustained charge speed is a (little bit) more meaningful thing you can express in GB. I am with the parent -- this is either a typo or a journalist quoting something he knows nothing about (what's that "h" in GWh? Strange capitalization; probably a typo; let me strike that).
  - epistasis 9y ago
    Your instincts would be wrong on this one. This is a technical article, that talks about all the right things for grid storage: value stacking, $/kWh (note the h), various install locations such as behind-the-meter, etc. They know what they are talking about. Currently, grid discussions happen mostly in the MW or GW space. Maximum instantaneous discharge speed is pretty much the most important characteristic for storage, up until very very recently, since it was mostly used for frequency regulation. Lately more and more articles are discussing total energy capacity instead, as this is discussed in wider circles than just those interested in the grid. Also note that the duration of discharge for a storage system is often implicit because it is deployed in an energy market where the bids are on fixed time periods (e.g. 4h). Ideally we'd know both the GWh and the GW, but the collated stats have been mostly GW so far. Guessing that they don't understand GWh vs. GW is pretty far off base. Though this may be a confusion of units that happens often in discussion with lay folk, it's not much of a concern when talking to people that are discussing the grid.
    - ptero 9y ago
      OK, thank you, good to know. I will re-read with this in mind to give this a fresh look.
    - ScottBurson 9y ago
      Well, it depends on who wrote the article. I see science journalists get this wrong frequently. And really, as you say, everybody talking about storage systems should be quoting both energy and power.
- Florin_Andrei 9y ago
  > GW is, however, a characteristic of an energy storage system, and just a valid and important measurement as the amount of energy it stores. Wrong. The watt is a measure of power, not of stored energy. These are different physical notions. So, yes, you could say that some storage facility can output up to so many GW, but that's actually a measure of how much energy per second can exit the system when it's being used. The proper unit for measuring an amount of energy that's stored in the system is the Wh (or its multiple the GWh), which has the same dimension as the joule, which is the standard unit of energy. GW is like how many liters of water per second can exit the storage tank when it's being emptied. GWh is like how many liters of water total are stored in the full tank. And yes, both are important when designing a battery system. But saying "GW is [...] a valid and important measurement as the amount of energy it stores" would fail you high school physics. GWh is static energy (or simply - energy). GW is energy moving from point A to point B, which is power. Here's a brief introduction to the basic meaning of these terms: https://cleantechnica.com/2015/02/02/power-vs-energy-explanation/ https://cleantechnica.com/2015/02/02/power-vs-energy-explana...
  - Zekio 9y ago
    for those of us too lazy to read about the difference between power and energy, there is EEVBLOGs recent video explaining it https://www.youtube.com/watch?v=YdbhnmA4M9g https://www.youtube.com/watch?v=YdbhnmA4M9g
  - epistasis 9y ago
    >Wrong. At no point do you actually say what was wrong about what you quoted. What do you feel is in error? >GWh is static energy (or simply - energy). GW is energy moving from point A to point B, which is power. Yes, obviously. This is HN. Generally it pays to assume that people know what they are talking about around here. It may be that you don't care about the power rating of the storage instance, but a utility does! They care about the power rating just as much as the total storage amount, as they are both essential design parameters. Particularly in the case of lithium ion, since many applications use discharges or charges less than an hour long (lithium ion batteries are typically designed with a W:Wh ratio of 1:1 - 1:4). The original article is citing a market report from IHS Markit. Now, I can't find the particular news release for this one, but IHS Markit uses both terms GWh and GW when talking about storage, and as market researchers if they were messing that up it would be a worthless report. So lets look at one of the recent reports: https://technology.ihs.com/590967/global-battery-energy-storage-pipeline-reaches-34-gw-in-q1-2017 https://technology.ihs.com/590967/global-battery-energy-stor... and one easier to check number: > This was largely a result of over 100 MW of projects being completed and commissioned in California in early 2017 as part of Southern California Edison and San Diego Gas and Electric’s response to the Aliso Canyon gas leak. Let's look at this other report on that 100 MW: https://www.greentechmedia.com/articles/read/aliso-canyon-emergency-batteries-officially-up-and-running-from-tesla-green https://www.greentechmedia.com/articles/read/aliso-canyon-em... >(CPUC) expedited the approval of around 100 megawatts of energy storage in Southern California Edison and San Diego Gas & Electric territories, in response to the Aliso Canyon blowout. >Tesla, Greensmith Energy and AES Energy Storage celebrated the completion on Monday of three large-scale lithium-ion battery projects totaling 70 megawatts -- consisting of 20 megawatts, 20 megawatts and 30 megawatts, respectively. Now, here all megawatts! And the mean it, because these the AES batteries were 37.5MW and 150MWh, and the Tesla battery is 30MW and 80MWh: http://www.utilitydive.com/news/inside-construction-of-the-worlds-largest-lithium-ion-battery-storage-faci/431765/ http://www.utilitydive.com/news/inside-construction-of-the-w... So yes, they mean GW and not GWh, and yes, that is a very meaningful statistic when talking about the grid. It's not the only one, and for bystanders, maybe they care about the Wh more than the W, but it's not like you can design a system without known both.
hwillis 9y ago
It's weird and not usually reported like that. Possibly it is a typo, but either way it's relatively closely coupled to storage capacity: li-ion is typically used around 1C, so ~1.3 GWh of capacity was deployed, within a factor of two or so.

epistasis 9y ago

GW is, however, a characteristic of an energy storage system, and just a valid and important measurement as the amount of energy it stores.

Gracana 9y ago
The maximum output is interesting to know, but if you asked how much my car's fuel tank held and I told you "100mph," you'd be understandably confused.
- epistasis 9y ago
  But we're not talking about cars, we're talking about the electrical grid. In the current stage of the grid and storage, storage capacity is used not for long duration transmission of energy, but shorter term filling in of power gaps. In the past few years that's been frequency regulation, and now the replacement of peaker plants, or instantaneous response when waiting the 10-15 minutes for a peaker plant to come online.
- deleted 9y ago
  [deleted]
- mulmen 9y ago
  A watt is a measure of power, not distance. The equivalent unit for a car would be horsepower. You could express the capacity of your fuel tank in horsepower hours. Since both are measurements of power and horsepower is defined in terms of watts you could even measure the capacity of your fuel tank in kilowatt hours. Similarly, you can define the output of your engine in kilowatts.
ptero 9y ago
Maximum discharge speed (which is one of the very few storage characteristics I can think of to be measured in GW) is pretty much irrelevant for storage systems. Add a few quick discharge capacitors that cost almost nothing and boom -- your max discharge speed shoots through the roof (but speed goes down for a very short time). Maybe sustained charge speed is a (little bit) more meaningful thing you can express in GB. I am with the parent -- this is either a typo or a journalist quoting something he knows nothing about (what's that "h" in GWh? Strange capitalization; probably a typo; let me strike that).
- epistasis 9y ago
  Your instincts would be wrong on this one. This is a technical article, that talks about all the right things for grid storage: value stacking, $/kWh (note the h), various install locations such as behind-the-meter, etc. They know what they are talking about. Currently, grid discussions happen mostly in the MW or GW space. Maximum instantaneous discharge speed is pretty much the most important characteristic for storage, up until very very recently, since it was mostly used for frequency regulation. Lately more and more articles are discussing total energy capacity instead, as this is discussed in wider circles than just those interested in the grid. Also note that the duration of discharge for a storage system is often implicit because it is deployed in an energy market where the bids are on fixed time periods (e.g. 4h). Ideally we'd know both the GWh and the GW, but the collated stats have been mostly GW so far. Guessing that they don't understand GWh vs. GW is pretty far off base. Though this may be a confusion of units that happens often in discussion with lay folk, it's not much of a concern when talking to people that are discussing the grid.
  - ptero 9y ago
    OK, thank you, good to know. I will re-read with this in mind to give this a fresh look.
  - ScottBurson 9y ago
    Well, it depends on who wrote the article. I see science journalists get this wrong frequently. And really, as you say, everybody talking about storage systems should be quoting both energy and power.
Florin_Andrei 9y ago
> GW is, however, a characteristic of an energy storage system, and just a valid and important measurement as the amount of energy it stores. Wrong. The watt is a measure of power, not of stored energy. These are different physical notions. So, yes, you could say that some storage facility can output up to so many GW, but that's actually a measure of how much energy per second can exit the system when it's being used. The proper unit for measuring an amount of energy that's stored in the system is the Wh (or its multiple the GWh), which has the same dimension as the joule, which is the standard unit of energy. GW is like how many liters of water per second can exit the storage tank when it's being emptied. GWh is like how many liters of water total are stored in the full tank. And yes, both are important when designing a battery system. But saying "GW is [...] a valid and important measurement as the amount of energy it stores" would fail you high school physics. GWh is static energy (or simply - energy). GW is energy moving from point A to point B, which is power. Here's a brief introduction to the basic meaning of these terms: https://cleantechnica.com/2015/02/02/power-vs-energy-explanation/ https://cleantechnica.com/2015/02/02/power-vs-energy-explana...
- Zekio 9y ago
  for those of us too lazy to read about the difference between power and energy, there is EEVBLOGs recent video explaining it https://www.youtube.com/watch?v=YdbhnmA4M9g https://www.youtube.com/watch?v=YdbhnmA4M9g
- epistasis 9y ago
  >Wrong. At no point do you actually say what was wrong about what you quoted. What do you feel is in error? >GWh is static energy (or simply - energy). GW is energy moving from point A to point B, which is power. Yes, obviously. This is HN. Generally it pays to assume that people know what they are talking about around here. It may be that you don't care about the power rating of the storage instance, but a utility does! They care about the power rating just as much as the total storage amount, as they are both essential design parameters. Particularly in the case of lithium ion, since many applications use discharges or charges less than an hour long (lithium ion batteries are typically designed with a W:Wh ratio of 1:1 - 1:4). The original article is citing a market report from IHS Markit. Now, I can't find the particular news release for this one, but IHS Markit uses both terms GWh and GW when talking about storage, and as market researchers if they were messing that up it would be a worthless report. So lets look at one of the recent reports: https://technology.ihs.com/590967/global-battery-energy-storage-pipeline-reaches-34-gw-in-q1-2017 https://technology.ihs.com/590967/global-battery-energy-stor... and one easier to check number: > This was largely a result of over 100 MW of projects being completed and commissioned in California in early 2017 as part of Southern California Edison and San Diego Gas and Electric’s response to the Aliso Canyon gas leak. Let's look at this other report on that 100 MW: https://www.greentechmedia.com/articles/read/aliso-canyon-emergency-batteries-officially-up-and-running-from-tesla-green https://www.greentechmedia.com/articles/read/aliso-canyon-em... >(CPUC) expedited the approval of around 100 megawatts of energy storage in Southern California Edison and San Diego Gas & Electric territories, in response to the Aliso Canyon blowout. >Tesla, Greensmith Energy and AES Energy Storage celebrated the completion on Monday of three large-scale lithium-ion battery projects totaling 70 megawatts -- consisting of 20 megawatts, 20 megawatts and 30 megawatts, respectively. Now, here all megawatts! And the mean it, because these the AES batteries were 37.5MW and 150MWh, and the Tesla battery is 30MW and 80MWh: http://www.utilitydive.com/news/inside-construction-of-the-worlds-largest-lithium-ion-battery-storage-faci/431765/ http://www.utilitydive.com/news/inside-construction-of-the-w... So yes, they mean GW and not GWh, and yes, that is a very meaningful statistic when talking about the grid. It's not the only one, and for bystanders, maybe they care about the Wh more than the W, but it's not like you can design a system without known both.

hwillis 9y ago

It's weird and not usually reported like that. Possibly it is a typo, but either way it's relatively closely coupled to storage capacity: li-ion is typically used around 1C, so ~1.3 GWh of capacity was deployed, within a factor of two or so.