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> The tried-and-true grid-scale storage option—pumped hydro [--> https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-country https://spectrum.ieee.org/a-bi
by nayuki 10mo ago
> The tried-and-true grid-scale storage option—pumped hydro [--> https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-country https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-cou... ], in which water is pumped between reservoirs at different elevations—lasts for decades and can store thousands of megawatts for days.
> Media reports show renderings of domes but give widely varying storage capacities [--> https://www.bloominglobal.com/media/detail/worlds-largest-compressed-carbon-dioxide-energy-storage-project-tops-out https://www.bloominglobal.com/media/detail/worlds-largest-co... ]—including 100 MW and 1,000 MW.
It looks like the article text is using the wrong unit for energy capacity in these contexts. I think it should be megawatt-hours, not megawatts. If this is true, this is a big yikes for something coming out of the Institute of Electrical and Electronics Engineers.
- B1FF_PSUVM 10mo ago> big yikes for something coming out of the Institute of Electrical and Electronics Engineers. Besides the unit flub, there's an unpleasant smell of sales flyer to the whole piece. Hard data spread all over, but couldn't find efficiency figures. Casual smears such as "even the best new grid-scale storage systems on the market—mainly lithium-ion batteries—provide only about 4 to 8 hours of storage" (huh, what, why?). I could also have used an explanation of why CO2, instead of nitrogen.
- hkt 10mo agoI'm sat here thinking: why not compressed or liquefied air?
- ted_dunning 10mo agoThe basic issue is that they need a phase change at a reasonable temperature. Liquifying air requires much lower temperatures than CO2.
- ycui1986 10mo agoi think it had something to do with CO2 can be made into supercritical state relatively easily, not for nitrogen or other common gases.
- raverbashing 10mo agoThis pretty much You can liquefy CO2 at a higher temperature than N2
- nine_k 10mo agoYou can do it easily with something like propane, or other larger molecules. But CO2 is non-flammable, largely non-toxic, and easily available.
- fragmede 10mo ago> only about 4 to 8 hours of storage" (huh, what, why?) Or it's just so obvious - to them! that it doesn't need to be mentioned, which then doesn't make it an ad. Lithium ion battery systems are expensive as shit, and not that big for how much they cost.
- gpm 10mo ago> provide only about 4 to 8 hours of storage" (huh, what, why?) Because the most efficient way to make money with a lithium ion battery (or rather the marginal opportunity after the higher return ones like putting it in a car are taken) is to charge it in the few hours of when electricity is cheapest and discharge it when it is most expensive, every single day, and those windows generally aren't more than 8 hours long... Once the early opportunities are taken lower value ones will be where you store more energy and charge and discharge at a lower margin or less frequently will be, but we aren't there yet. Advertising that your new technology doesn't do this is taking a drawback (it requires a huge amount of scale in one place to be cost competitive) and pretending it's an advantage. The actual advantage, if there is one, is just that at sufficient scale it's cheaper (a claim I'm not willing to argue either way).
- alextingle 10mo agoIt ought to be cheaper at scale. Batteries' cost scales linearly with storage capacity. Cost for a plant like this scales linearly with the storage rate - the compressor and turbine are the expensive part, while the pressure vessels and gas bags are relatively cheap. The bigger you build it, the less it costs per MWh of storage.
- jakewins 10mo ago> Energy Dome expects its LDES solution to be 30 percent cheaper than lithium-ion. Grid scale lithium is dropping in cost about 10-20% per year, so with a construction time of 2 years per the article lithium will be cheaper by the time the next plant is completed
- aaa_aaa 10mo agoBecause CO2 is a magic word. It can open free money doors. Or at least it used to.
- Waterluvian 10mo agoIf 1 watt is 1 joule per second then, honestly, what are we doing with watt-hours? Why can’t battery capacity be described in joules? And then charge and discharge being a function of voltage and current, could be represented in joules per unit time. Instead its watt-hours for capacity, watts for flow rate. Watt-hours… that’s joules / seconds * hours? This is cursed.
- B1FF_PSUVM 10mo agoIt's easier to figure out for people that measure power in watts and time in hours ... 1 kW for 1 hour is 1 kWh. That camel's nose was already in the tent with the mAh thing in phone/etc batteries, now with electric vehicles we're firmly in kWh land. Not to mention that's what the power utilities used all along ...
- SigmundA 10mo agoA watt of power multiplied by a second of time has an agreed upon name called joule, but a watt second is also a perfectly valid SI name. A watt is a joule of energy divided by a second of time, this is a rate, joule per second is also a valid name similar to nautical mile per hour and knot being the same unit. Multiplication vs division, quantity vs rate, see the relationship? Units may have different names but are equivalent, both the proper name and compound name are acceptable. A watt hour is 3600 joules, it’s more convenient to use and matches more closely with how electrical energy is typically consumed. Kilowatt hour is again more directly relatable than 3.6 megajoules. Newton meter and Coulomb volt are other names for the joule. In pure base units it is a kilogram-meter squared per second squared.
- thekoma 10mo agoPower plants are often described in terms of (max) power output, i.e., contribution to the grid. So, I can see how it might confuse a writer to then also talk about storage inadvertently. But also, the second paragraph already describes the 100 MWh vs MW nuance.
- heisenbit 10mo agoIt is not a nuance in an article that focuses on storage from the supposed premier professional association. As an engineer I would expect typical energy content (median/average) of the top 10 hydro pump projects and also some discussion about the availability of suitable sites. I think one should strive for at least high school level physics. There is no need to push out texts that can be easily surpassed by any current llm.
- calmbonsai 10mo agoI'm old enough to remember when IEEE Spectrum was a respected technical publication.
- while_true_ 10mo agoCalifornia found out pumped hydro isn't so "tried and true" when it was shut down during a drought due to lack of water behind the dam.
- hvb2 10mo agoNot every area is as messed up as the Colorado river watershed... All users (states) were given an allotment which, when it was set, was more than what would ever be the yearly supply. From the outset it was essentially a free for all. Everyone was happy, they kinda got what they asked. It's just that they were all living in a paper reality
- nayuki 10mo agoI should have explained in my original comment why I think those sentences are wrong. I'll do so now. > pumped hydro [...] can store thousands of megawatts for days. You can't "store" a megawatt – because you can only store energy, not power. But another interpretation is, if you actually store thousands of megawatts (i.e. gigawatts) for days, then at the very least, 1 GW × 1 day = 24 GW⋅h. If we take "a few" to mean 3, then 3 GW × 3 day = 216 GW⋅h. I'm not sure there exists a large enough pumped hydro plant in the world that stores 216 GW⋅h of energy. So I think the article meant to say, "store a few gigawatt-hours to be released over a period of a few days". > Media reports show renderings of domes but give widely varying storage capacities—including 100 MW and 1,000 MW. Once again, you can't store megawatts of power, full stop. You can store megawatt-hours of energy. The linked article at Bloomberg said that a project in China is building 600 MW of wind power, 400 MW of solar power, and 1 GW⋅h of energy storage – which is the correct unit.