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'No-water' hydropower turns England's hills into green and pleasant batteries
(www.rechargenews.com)
this post was submitted on 17 Aug 2023
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This is logically efficient from a technical standpoint, but from a practical perspective is a terrible idea. You're only getting 2-2.5x th energy storage out of the process, but in return you're effectively requiring that the entire fluid system be isolated from the environment. Toxicity aside, you can't do anything with the fluid outside of the system. It's probably not something you want local fauna drinking, nor do you want even the slightest chance of this leaking into the local aquifers. I presume that, if it's not fully isolated, the fluid mix balance would have to be adjusted to offset evaporation of the water. And if the plant turns out not to be as great at you hoped hat do you do with the fluid?
Some numbers - a quick google says "According to Ofgem, the typical household in Britain uses approximately 2,900 kWh of electricity annually." I'm going to round that up to 8kWh/day. For a small village of, say, 1250 homes and a three day storage capacity, that's 30MWh. 1MJ (MWs) is 1000kg (one metric ton) stored at 100m - the upper end of this project. Since 3600 seconds per hour x 1MWs = 1 MWh, and we want 30, that's 1MT x 3600 x 30 = 108,000 Metric Tons of this high density liquid needed for a small project to put a 3 power day buffer in place for a town of 1250 houses. WTF are you going to do with 108,000 metric tons of high-density fluid if you decide is isn't working? Your reservoir would only need to be 25% bigger (wider, longer, and deeper/taller) to just do the whole thing with water and you wouldn't need to figure out how to get 3500 full size tanker trucks to transport it all away somewhere for a different project for for de-slurry processing.
If the fluid is what I'm thinking it is (calcium carbonate in water with a stabilizer), fluid loss would just be water loss and they wouldn't go to great pains to isolate it. They'd just add more water, since most of the weight they're pumping is the calcium carbonate.
Hydro is used to smooth out peaks and troughs in the power supply. You're not even close to getting a useful estimate.
The fifth largest hydroelectric power station in the UK is 160MW
100MW by 2030 is a pretty big deal.
I agree you need much less capacity because you'd usually just want to even out fluctuations, but I think the general gist of the comment is still true: you need just 2,5x the amount of water to produce the same amount of energy. The article says very little about the liquid, and very little about why this would enable them to build this capacity much quicker. A little more data would be nice.
More information is alway s useful. But it's pretty obviously quicker to build because it only needs to handle 40% of the liquid and it's not on a mountain.
The article in this post is written by yet another dunce who doesn't know the difference between energy and power. That single generating station would fill 100 MWh of capacity in 37.5 minutes.
I mean, we actually could use that damn water, for things, it's a perfect reservoir for drinking and/or irrigation.
Who in their right mind looked at this and said "You know, mercury has a higher specific gravity than water, it might even work better!!"
It's 2.5x heavier than water so can produce 2.5x the power for any given volume.
We have a lot of hydroelectric. But we don't have the mountains to build much of it.
Again, we can use the water for things, and water is something we can get more of one way or another.
A 2.5x multiplier doesn't seem as worth it to me, especially when we can do stuff like add hydrothermal storage to that number easily, among other things.
We can get plenty of water. We can't get plenty of suitable sites.
If the water leaks we can shrug our shoulders.
If the calcium carbonate slurry leaks we will feel more awkward.
Entirely true, but since we're talking volume, this is only a 25% increase in linear dimensions (for the advertised 2x increase) or 35% (for the 2.5X maximum slurry density). If we are limited to a specific height of retention, that's 40% and 60% (rounded). Note: for structural capacity, like a tank, retaining a g=2.5 liquid requires substantially higher strength than a g=1 liquid (for a given retention height). Since this is the internet and should source my knowledge: I know this because I happen to be an engineer who designs retaining structures. Anyway...
For the effective cost of creating and maintaining the slurry, maintaining the integrity of the system (and keeping out wildlife), and the cost of decommissioning the otherwise unusable fluid, you're likely talking about a reduction in area of 20-38% (1/8) to switch from using plain water to this engineered material. I don't disagree that there may be some edge cases where the increased risk and expense is justifiable, but it's hard to see this being viable except as some kind of tech demo.
I guess we'll just have to wait and see. They're doing it and there's an outside chance that they've thought it through properly (and a good chance that they have not, of course).
What's 108,000 tons in volume?
It's designed to go underground. I see it like water towers, every town has one to get mains water pressure and a store of water.
Wouldn't these be similar for energy? 3 days emergency backup power sounds great, plus it smoothes peaky renewables.
Edit. It's about 40x swimming pools
https://www.themeasureofthings.com/results.php?comp=volume&unit=cm&amt=100000