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Interesting. There's a good video describing the operation here: https://www.youtube.com/watch?v=cOWjwwKSR78 https://www.youtube.com/watch?v=cOWjwwKSR78 Afte
by nkurz 5y ago
Interesting. There's a good video describing the operation here: https://www.youtube.com/watch?v=cOWjwwKSR78 https://www.youtube.com/watch?v=cOWjwwKSR78
After watching it, I now understand that they aren't flooding the entire borehole, but rather are building a smaller high-pressure chamber at the bottom. The chamber is connected to pipes to a surface reservoir. When air is pumped into the chamber, it displaces water up toward the surface. When generating, the water flows back into the subsurface chambers, forcing out the high pressured air.
- mirekrusin 5y agoI wonder what is the loss/recovery %age.
- epistasis 5y agoI don't have specific numbers, but in other batteries of this type, the length of storage time before discharge affects the efficiency. Heat stored from compression is lost over time.
- ehnto 5y agoI was curious about that as well. I think it's best application would be to compensate for large amounts of rising and falling generation from solar grids, that way the cycle is daily. Being quick to come online and meet demand makes it good for maintaining grid stability at a much lower cost as well, like the Hornsdale Power Reserve facility https://hornsdalepowerreserve.com.au/ https://hornsdalepowerreserve.com.au/.
- keewee7 5y agoWhat goes into building and burying large scale underground structures like those air caverns?
- mschuster91 5y agoNot much, technologically this is a conventional mine project, only that you mine air volume instead of rock and have to take care of the cavern being reasonably airtight afterwards.
- jhallenworld 5y agoAlso you could do it underwater if you live near a coast. Basically an upside down cup with a pipe in it, sunk as deep as possible.
- fastball 5y agoThe same company has actually done this[1] with the city of Toronto. [1] https://www.youtube.com/watch?v=GicQwXbNnv0 https://www.youtube.com/watch?v=GicQwXbNnv0
- nkurz 5y agoThe video is from 2015, and says it was a 2 year pilot project. Do you know if there are there any updates on how the project went? Is it still operational? Did they build any more?
- fastball 5y agoNot sure, this is the page on the companies website: https://www.hydrostor.ca/toronto-a-caes-facility/ https://www.hydrostor.ca/toronto-a-caes-facility/
- buryat 5y agoyou don't have to build those caverns as they already exist and we have extracted gas and liquids from them, also the volume should be already known as we know how much we pumped out (unless it's an old site)
- srcmap 5y agoIsn't the complexities related to making those caverns air and water tight for long period of time for long term energy storage requirements?
- tikkabhuna 5y agoTotally out of my depth here, but does cooling the gas down have the added benefit that it'll be heated by the earth whilst stored?
- deleted 5y ago[deleted]
- notatoad 5y agowhat would be the benefit to it being heated by the earth during storage? all the temperature management here looks to just be counteracting the temperature changes that naturally occur when you compress or expand a gas. i imagine if you compressed it and then pumped hot air into water-filled caverns you'd get some negative effects of thermal shock.
- halpert 5y agoHot air should have higher pressure, so theoretically you could get more displacement. But your pumps also have to work harder to create a pressure differential. Hard to say which effect would be bigger.
- locuscoeruleus 5y agoWouldn't the cooled down gas expand when heated leading to higher pressure, so you need to pump gas down?
- JohnL4 5y agoI'm guessing not. Earth's heat is way lower down. Think of a cave: always cold. I think what's going on is they're taking the heat out and storing it more efficiently than just dumping it down the ground, where (1) it would leak away, representing energy loss, and (2) as it leaks away, the air would lose pressure. (It would leak away b/c it's harder to insulate an entire mine, basically.) So, they pull it out ahead of time and put it back in when they decompress the air (which I think would add pressure back in due to heating a gas and maybe reduce problems caused by super-chilling other plant hardware? Anyway, seems fitting to add back what you took out if you're shooting for a closed system.)
- laputan_machine 5y agoThe big question is how on earth are they digging out these caverns? That seems like a huge challenge, given that they're so far underground. Everything else seems relatively straightforward
- crunchyfrog 5y agoShaft mining is often used to reach underground deposits of iron, coal, etc. I believe they'd use the same process here.
- rplnt 5y agoIt says repurposing old mining operations. Not sure how feasible that is.
- ed_balls 5y agoI had a similar idea for repurposing an old mining operation. You take a closed gold, uranium or copper mine which is 1000-2000 meters deep. You create a nuclear rector at the bottom with "fire and forget" design. Only robots can do the maintenance. After 60 years you disable it, pour concrete into the shaft and move to the next location. If it melts, who cares? It's not gonna poison water supply. Why was this not built before? I have no idea. Maybe robots are essential, we didn't have deep enough mines that were abandoned, energy was cheaper, no push for no emissions, it's not economical, other risks.
- creato 5y agoYou need a hot and cold reservoir to generate power. Where is the heat going to go? This is why power plants are often built on rivers or near the ocean.
- ed_balls 5y agoyou need to pump water, probably flooding 80% of the mine. Since there are no humans involved 70+ celsius is not a problem.
- sauwan 5y agoIs the voice in that video AI generated?
- flyinghamster 5y agoA similar thing is done for natural gas storage. A well will be drilled into a rock dome that lies atop a layer of saltwater-saturated sandstone. Gas is then pumped into it, displacing the water, and then can be withdrawn later. A report from 1961: https://www.ideals.illinois.edu/bitstream/handle/2142/42910/undergroundstora318bell.pdf?sequence=2&isAllowed=y https://www.ideals.illinois.edu/bitstream/handle/2142/42910/...