190
'No-water' hydropower turns England's hills into green and pleasant batteries
(www.rechargenews.com)
this post was submitted on 17 Aug 2023
190 points (96.6% liked)
Technology
59483 readers
5306 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
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.
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.
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).