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More sciencey bits I don’t understand

The hillside projects would mimic the UK’s traditional hydropower plants by using surplus electricity to pump water uphill, and later releasing the water back down the hill through turbines to generate electricity when needed.

But the “high-intensity” hydro projects use a mineral-rich fluid, which has more than two and a half times the density of water, to create the same amount of electricity from slopes which are less than half as high.

The company behind the plans, RheEnergise, said the project would pump the dense fluid up a hill with a height of 200 metres, at times of low electricity demand. It would be held in an underground storage tank larger than an Olympic-size swimming pool.

This high density fluid, there’s no formula for it revealed. But OK, so, something that’s 2.5 times the density, that should indeed mean you need a smaller drop to generate the same power, right?

Move 250 lbs through 100 yards, same as 100 lbs through 250 yards – right?

I’d probably start muttering to myself that density and – well what? viscosity? – are closely related and we might not expect a thicker liquid to turn a turbine in quite the same way. But, umm, the initial insight is valid or not? That initial insight by these developers that is?

That they’re flogging their stock online through their website is a different matter……

42 thoughts on “More sciencey bits I don’t understand”

  1. It would take at least as much energy to pump it up the hill as you would get from it coming down again. Is there no way of using capillary action to get it up there for nothing?

  2. In theory it should be – potential energy = mgh . I have no idea of the practicalities.

    But if they’re using a special mineral-rich fluid (instead of plain old water), surely something like iron ball bearings would be an even better choice?

  3. ” surely something like iron ball bearings would be an even better choice?”
    Or winch a wagon load of lead up the hill. 11 i/2 times density of water ( if there isn’t enough depleted uranium to go around) Easier to handle than liquids & a lot less friction losses. Only point of contact would be between the wheels & rails.
    But I’m guessing that’d be far too simple to screw a fortune out of gullible green politicians.

  4. Gravitational potential energy = mgh === mass * local g * height
    Double mass, halve height, same energy.

    An Olympic-sized swimming pool is 2.5M litres (2.5M kg using water) * 9.8 * 200m altitude = 4.9GJ = approx. 1.3MWh
    Even allowing for this new super slurry, that’s only 3.25 MWh which is a pissing-in-the-wind amount of energy — at 85% efficiency it’d provide backup for Sizewell B for just over 8 seconds

    Advantages of water over novel fluid:
    Well understood. We know what alloys to use and how existing ones are affected by high-pressure water; we don’t know what effects this new slurry might have on pipes and especially turbines, seals etc.
    When it inevitably escapes into the environment, it doesn’t matter.

  5. Come to think of it, winch environmentalists up the hill. You couldn’t find anything more dense. I’d recommend by the necks.

  6. Why not use mercury?

    13x denser than water, so much more energy potential.

    Risk of insanity if it leaks, but given how everyone is behaving with all this Covid nonsense, would we even be able to tell?

  7. Matt: +100. Same order of silliness as grid batteries with the added silliness of inertia that electrons don’t have. So it can’t even be used for second-by-second frequency control.

  8. I quite like this idea, big weight, deep hole.

    Sounds like another thing that will give a bit of power for a relatively short time. Indeed they say 8min – 15 hrs.

    I don’t get why they’re suspending the weight freely?
    Why not use some bearing rails and low friction sliders as a guide? The system proposed, using tensioned guide wires, just sounds overly complex and is just more to go wrong.
    Use bearing rails, Fill the hole with nitrogen to prevent corrosion and just have the ability to lock the weight at the top occasionally, in a room where there is oxygen to allow the bearings to be greaseed occasionally if necessary. Friction Losses would be minimal, and far more reliable. You only need oxygen at the top, and nitrogen sinks anyway so the hole wouldn’t need purging every time.

  9. @BiS

    I really liked that idea until I started thinking about how you could make it more efficient…

    The logical extension is to do away with the wagons and rails entirely, and use an old mine shaft or similar to raise/lower the lead/iron/unobtanium. Now, you could increase the capacity by using an endless chain and loading/unloading blocks at the top/bottom as required so that more mass can be raised/lowered without having to strengthen the chain, as the stronger the chain the more resistance there is going to be in it. Of course, there would be losses doing the loading/unloading at which point a fluid of some description becomes a great idea because it’s easier to marshal.

    Another problem here is that your drum or whatever that you’re using to haul the chain is going to be turning slowly, so would need to be geared to a motor/generator and gearing causes losses. A turbine can be tuned so that it’s turning at a suitable speed for the generator regardless of flow, so if you’re moving a fluid then… Oh, we seem to have invented pumped storage.

    The issue isn’t the technology, it’s the implementation. If you were somewhere where it was feasible to have a 2,000m drop instead of a 200m drop, you’ve immediately increased capacity tenfold for minimal additional cost. And if land is cheap enough, the storage tanks aren’t expensive either. A sq km “lake” top and bottom, 25m deep gives you 25M tonnes of water, so you’ve increased capacity a further 10,000x for ~130GWh which is actually a useful amount of energy.

  10. Not sure what this fluid actually is, but the basic physics is simple enough. However, and you don’t need any particular physics knowledge to understand, whatever power can be derived from this fluid, more energy will be needed to get it to the top of the hill. This is true whether it’s water or liquid unobtainium.

    More sensible than death star sized batteries though, but what isn’t?

  11. The illustration in The Guardian is wrong. It compares a large hill and large water tank with a small hill and small tank of “high density fluid”. The tanks should be the same size or the hills should be the same size. Their illustration is … deceptive?
    Maybe “deceptive” is the wrong word, but it’s all I can come up with, but this is The Guardian so maybe I shouldn’t expect accuracy.

  12. If you go to the trouble of getting the liquid to the top of a hill, why bury it in a tank underground?

  13. You need less of a denser liquid, more of a less dense liquid, all other things being equal. And/or you can pump it less high. Everything else stays pretty much the same regarding the energy management.

  14. It would be held in an underground storage tank larger than an Olympic-size swimming pool.

    Take a lot of building, for not very much volume. And all on top of a mountain!

    Still, nice to see Snowdonia National Park be put to some use, and become an industrial sized pump storage syste, instead of all that useless nature stuff (no business casde you know:)). And think of all those highly paid unionised jobs for welsh ex – coal&slate miners.!

  15. You need less volume of a denser liquid to get the same weight and the same power for a given height or the same volume and more weight to get same power for a lesser height *but* if it has higher viscosity then you lose some of th power on the way down and it takes more energy to pump up so the efficiency of the system is much lower.
    Do not invest in this project.

  16. So Much For Subtlety

    bloke in spain February 8, 2021 at 8:50 am – “Or winch a wagon load of lead up the hill.”

    Why bother with lead? Use rocks. The best thing is you can blow the top off Snowdonia and get the first trip for free!

    Also easy to store.

  17. There are solutions called ‘completion fluids’ used in oil drilling, typically with densities up to 2.3, which are aqueous mixtures of zinc/calcium bromides or formates & calcium chloride. You could easily get up to a density of 2.5 using more Zinc bromide or zinc iodide & still ensure they didn’t crystallise out in cold weather. Viscosity won’t be very significant, although there will be slightly more losses through enhanced friction/less efficient pumps. Many years ago I designed a silver nitrate crystalliser plant with similar densities- plant commissioning was delayed because the client couldn’t afford to fill the crystalliser (4′ diameter), due to the Hunt brothers (?) trying to corner the silver market at the time…

  18. @Matt

    I really liked that idea until I started thinking about how you could make it more efficient…”

    The trick is, to start with the problem & work out a solution to it. Not start with the solution, then look around for a problem it could solve.
    The simplest solution would do what they’re asking would use an old electric train & some spare railway line. Driven up the hill from electricity from a conductor rail. Returns the electricity to the rail via the regenerative breaking. Amount of energy it stores depends on how many bags of sand are in the wagon it pulls. Piece of piss, if you were stupid enough to think it was a solution to anything. All your infrastructure comes for free.

  19. “However, and you don’t need any particular physics knowledge to understand, whatever power can be derived from this fluid, more energy will be needed to get it to the top of the hill. This is true whether it’s water or liquid unobtainium.”

    True, but the idea is that sometimes, you might have a glut of wind or solar power. You don’t need it right now, and will go to waste. By pushing it up the hill, it’s sat ready for when you need the demand. You might only get part of the solar you collected, but that’s still of some value (how much, I don’t know).

    BTW Don’t we have some other dense things we could use instead? Bits of the Olympic stadium, stone from empty, disused listed buildings? Diane Abbott’s brain?

  20. RLJ: I did like your Gravitricity. It looks so nice and simple. Of course, if you said, ‘What do you know about mechanical engineering?’, I’d have to say SFA.

    However I think bilbaoboy got it right when he said ‘Use fossil fuel.’

  21. Is there any way to incorporate Guardian scribblers in the mechanism… if high density is required – surely that which bends light would be of some utility?

  22. @Patrick: dear old Ambrose is a sucker for sciencey stuff. Still, the idea of turning a liability into an asset is attractive.

  23. So Much For Subtlety

    Liquid metals can be pumped electro-magnetically. Don’t have a problem with turbine-wear.

    We have thousands of years of experience with water. We ain’t going to be using something else for the foreseeable future. It might make sense for engines to boil some other liquid – and high pressure steam is terriuble stuff – but it is just not going to happen.

  24. @bloke on M4

    Of course, but with a proper power grid, the surpluses – when spare capacity is available – are generally pretty predictable – at night.

    Solar at night?

    Wind? This is almost by definition gluts at unpredictable times.

    This scheme is just another form of back up (i.e. cover) for a “renewable” infrastructure that clearly is not fit for any sort of real world purpose (which fossil fuel back up currently manages to cover for).

    I wouldn’t touch it with a barge pole but have a sinking feeling that my pension funds and cuckolded governments will do so for me.

    Oh and lets not forget the millions of milk floats (blessed be our saviours!) that are going to be charging overnight for free.

  25. The electrical storage capacity of an Olympic swimming pool full of the gunk at 200m is the equivalent of 50 electric car batteries. It “might” be more efficient but it’s going to be a very expensive option. I won’t be buying shares in them.

    Another way of looking at the energy stored is about 320 cubic meters of gas i.e. roughly one eighth of an Olympic swimming pool.

  26. Some suggestions above have got me thinking. What if we melted down Diane Abbott ( and for good measure Richard Burgon) how long would that last us ?
    In Scotland they could use Iain Blackford.

  27. Mark,

    “This scheme is just another form of back up (i.e. cover) for a “renewable” infrastructure that clearly is not fit for any sort of real world purpose (which fossil fuel back up currently manages to cover for).”

    It’s rather fortifying the scam, isn’t it? “well, wind and solar aren’t predictable, but we can do this for those times”. And if you aren’t crunching the numbers, you might not ask how much of this we’re going to need for the ad break during Coronation St. The scam can keep rolling on.

    At some point, whether because the penny drops on the numbers, or just blackouts, people are going to get the scam and it’s going to be like the collapse of the housing market in 2008.

  28. The Guardian writer is either a scientific ignoramus, or easily-misled – or both. For me, the key is when they talk about “gentle gradients”, as though the slope of the hill has anything to do with it.

    Massive costs and bleeding-edge technology for truly-piddling amounts of energy storage. To have any serious utility, pumped-storage systems need to be very big, even using whatever super-secret magic liquid they are proposing. A ridiculously-complex solution to an already-easily-solved problem. File next to ‘200 mpg carburetor’.



  29. @Bloke on M4

    I have a feeling it going to be blackouts, but even then it’s not the green god that’s at fault (how can a god possibly be?)

    No, like all religions from Catholicism to communism you just need faith.

    The penny has dropped for so many, as reading comments on blogs like this reveals. They call us “deniers” and “heritics” while at the same time believing themselves to be rational and scientific.

    I often wonder how the human race managed to get as far as it has.

  30. Why piss about with any of I?

    Just build nukes/fossil fuel plants and crucify an eco-freak every 100 yards from here to Paris.

  31. Arthur: interesting. I looked in vain for CO2 until I realised they called it Carbonic Acid back in the day. It doesn’t feature something I’m sure I read about, which is super-critical CO2 as a working fluid in a closed cycle engine. Perhaps I was confusing it with decaffeinating coffee, which does use super-critical CO2 in some processes.

  32. David Mackay said that for the UK, a pumped storage backup for alternative energy would have to be five hundred foot deep and in area the extent of the Lake District.

    My rusty memory tells me that some Ancient Greek guy experimented with weights, ropes and pulleys. The idea has been around for a couple of thousand years and has never taken off, but that’s not the intention with this latest harebrained scheme anyway. The intention is to fund a luxurious dotcom lifestyle for the founders.

    A cheap source of weights would be the tons and tons of bird and bat carcasses that clutter up wind and solar projects.

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