sethoflagos
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Posts posted by sethoflagos
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9 hours ago, Linkey said: Ok, I have more arguments:
https://en.wikipedia.org/wiki/Anti-nuclear_movement_in_Switzerland
For those who just can't get enough of this thread, tune into BBC Brit - Channel 120 on African Dstv - and watch endless repeats of 'Pointless'
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19 hours ago, MigL said: The main discriminator for the pumped/reservoir approach, as compared to the large flywheel approach, seems to be the efficiency of the pumps compared to the efficiency of the flywheel bearings.
The main practical discriminator is scale.
Given an amenable geography, hydro comfortably works with GW. Flywheels work with MW.
Ditto weight-lifting.
20 hours ago, MigL said: Does anyone have relevant 'ballpark' figures, and how they scale ?
The efficiency figures for pumped hydro are clear enough. Large water pumps have a hydraulic efficiency ~85%, and Francis turbines (typical design for large units) can reach ~95% efficiency. Pipe and distribution losses add a couple of per cent each giving the overall round trip efficiency of ~75% I quoted earlier. I don't believe solar evaporation losses are a thing in Wales.
But bear in mind that the context is trading up low cost wind energy on a stormy night in November to high value peak load GW at very short notice on Christmas Eve with perhaps a ten-fold increase in billable revenue - and the efficiency only needs to be reasonable.
Availability at required scale is the ultimate measure.
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1 hour ago, exchemist said: I think, though, I would expect the losses to be lower than with pumped storage, as there won't be losses to turbulence and "slippage" through the turbine.
Don't forget that winching systems rely on belt friction for cables to grip pulleys etc. (capstan equation and all that good stuff), and high ratio gearboxes can have significant losses. I wouldn't contradict your expectation as such, but I'd prefer to check the data first. It may not be quite so clear cut.
Again... no free lunches.
Not to mention the capital costs involved...
(Apologies for delayed response - network went awol for 24 hrs)
23 hours ago, studiot said: China (Largest System): The Dinglun plant, completed in 2024, uses 120 units, each with high-speed magnetic bearings. It is capable of storing 30 MW of power, sufficient for grid-level frequency regulation.
Does anyone actually understand this?
Is that 30MW for a millisecond or a millennium? Surely the unit of interest is Joules.
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8 hours ago, Ken Fabian said: That sounds like a long established technology called Synchronous Condensers and Australia is currently adding them to cover the withdrawal of thermal (spinning) power plants.
Not quite the same thing, Ken.
Granted, much of the physical hardware is the same, but syncons are specifically designed for power factor correction, and therefore have excitation circuitry designed for the production of reactive power, either lead or lag, as an alternative to (typically) thyristor switched static VAR compensators (SVCs).
What they don't do is generate torque to any large degree and are thus unable (in standard form) to replace active power generation shortfalls beyond a few cycles.
The flywheel version provides the necessary large energy storage capacity to fulfill that role.
It's interesting to consider whether these various functionalities could be combined in a single machine, though I suspect that idea would run into significant degrees of freedom issues.
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11 hours ago, sethoflagos said: I've had similar thoughts.
However, the units couldn't be 'unpowered' otherwise there would be no electrical coupling. What I'm not clear on is whether rotational KE on the demand side (power consuming units) is as useful as that of power generating units. Both tend to flatten the rate of frequency change, but act in opposite directions which might be an issue.
... Not an issue apparently, see Flywheel Storage Power System
A flywheel-storage power system uses a flywheel for grid energy storage, (see Flywheel energy storage) and can be a comparatively small storage facility with a peak power of up to 20 MW. It typically is used to stabilize to some degree power grids, to help them stay on the grid frequency, and to serve as a short-term compensation storage. Unlike common storage power plants, such as the pumped storage power plants with capacities up to 1000 MWh, the benefits from flywheel storage power plants can be obtained with a facility in the range of a few kWh to several tens of MWh.[1] They are comparable in this application with battery storage power plants.
Reading between the lines, the limited current scale of such installations seems due to a lack of perceived urgency rather than any significant technological limit. And the UK always has Dinorwig - it would take one monster of a flywheel to compete with that.
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14 hours ago, exchemist said: I've only just read this. Would it be a silly idea to run a couple of vast flywheels, just to add "ballast" to the system? One could even simply retain a couple of these big turbo-alternator sets, unpowered, and spun up and maintained to 50Hz off the grid.
I've had similar thoughts.
However, the units couldn't be 'unpowered' otherwise there would be no electrical coupling. What I'm not clear on is whether rotational KE on the demand side (power consuming units) is as useful as that of power generating units. Both tend to flatten the rate of frequency change, but act in opposite directions which might be an issue.
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5 hours ago, MigL said: I assure you no 'slagging' was intended on my part; String Junky, on the other hand, can be awfully mean 😄..
Just intended as a gentle reminder of something I'm sure you already know 🙂.Absolutely no offence taken 🙂
Though I will continue to discriminate between those artists who sacrificed the full 10,000 hours of childhood to their vocation, and those who chose an easier path 😜
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Having been slagged off somewhat by @MigL and @StringJunky for making somewhat disparaging remarks about one-fingered Casio playing, I had to remind myself that my favourite small brass ensemble occasionally indulge in one-fingered trumpet playing.
While I''m at it, couldn''t resist posting this faulous p***take too
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12 hours ago, MigL said: Music is not an instrument; it is a composition.
... or an interpretive performance of that composition, maybe?
My comment was directed at a pretty abysmal pedagogical method - akin to how I was taught to play the recorder at age 5 by having the edge of a ruler crack my knuckles whenever I played a wrong note. Your reply seems non sequitur. A misunderstanding perhaps?
12 hours ago, MigL said: You would be surprised what a former member of Depeche Mode could do with a Casio in 1982, along with Alison Moyet.
I was thinking more of this minimalist masterpiece
12 hours ago, StringJunky said: Music is the art and can be expressed in any form. You don't have to be an artisan/craftsman with some instrument to make music. A person that can create perfect copies is not an artist, even though their skill may be immense; s/he is a technician. Skill alone does not make an artist.
Ditto, really.
Though if the performer lacks the basic technique a piece demands, it's really difficult to make it a musical experience for the audience.
Florence Foster Jenkins springs to mind.
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1 hour ago, Linkey said: In particular, these laws are always aimed at suppressing the small businesses, because small businessmen are less dependent on the power and can overthrow it.
This is untrue. Parliamentary representatives are unlikely to be elected in the first place unless their manifesto policies can convince a majority of the electorate that they will benefit financially - ie that there will be an acceptable degree of wealth distribution in their favour.
All things being equal, large producers have an intrinsic economic advantage over smaller producers due to economies of scale. Costs are not a linear function of output. The actual degree of proportionality varies a little with with context, but a common rule of thumb is that capital costs scale with output^0.6 for example. Conspiracy is not a prerequisite for this to happen.
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1 hour ago, Sensei said: I imagine that nowadays it can be done much better and easier than several decades ago. As long as you want to make it easier. I would use a touchscreen that displays hints about which piano keys to press in a given song.
That's how to get a noise out of a Casio with one finger. Not how to become a musician.
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Edited by sethoflagos
Dear Mein Drumpf,
Thank-you for alerting us to our 'GREAT STUPIDITY' in agreeing with Mauritius a 99 year lease on Diego Garcia at considerable cost to ourselves while allowing your military personnel to squat on the island FOC.
After due deliberation, we have decided to give you the option of continuing to make reasonable use of our facilities at the fair market rate (as determined by our diplomatic research team in Beijing) of $100 billion pa.
If you choose not to take advantage of these terms, please accept this message as a notice of eviction effective immediately, as we have an alternative tenant who is very keen to do business with us.
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54 minutes ago, exchemist said: How about Brandenburg 6? My favourite of the set, I think, though 3 runs it close.
You ask that of a trumpet player?
For us, the 2nd is of such stratospheric significance, the others barely register.
So my favourite Brandenburg is the performance by Friedemann Immer
https://youtu.be/3HSRIDtwsfM?si=9SL0Fo-Y1v9-0c9a
I imagine the ripieno viola scoring is exemplary, as one would expect of JSB.
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11 hours ago, TheVat said: UHT goat milk might also be good if there are any digestive issues not resolved by the fermentation. It has the A2 casein, which some find easier to handle. (A2 beta-casein is what is found in human milk)
Useful to know. Beginning to suspect my 'inconvenience' may be down to brief fever and course of strong antibiotics over Marxmas. I've never really done allergies and the like (touch wood).
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On 1/14/2026 at 4:12 PM, StringJunky said: No, I didn't, using pasteurised, it was fine. I think the culture soon overwhelms any other strains in there. I wouldn't bother heating with uht.
Tried a one litre UHT batch without heating and got 100% conversion to homogenous yoghurt. Negligible whey separation. Not that I can't find a use for the whey, but it's good to have the flexibility of a choice.
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[Chem-Applied] Vapour pressure of Pure Liquids A & B are 450 & 700mmHg respect. @350 K . Find comp. of liquid mix, total Vapour pressure is 600mmHg and Vapour phase composition
in Homework Help
Since xA+xB = 1 for a binary mixture, your equation
simplifies to xA = xA which is true but of no use to anyone.
Your terminology
is nowhere explained, so again, that is no use to anyone.
Perhaps you should start with the fundamental definition of xA and xB in terms of molar quantities nA and nB in the liquid phase. That might help get us all on the same page.
Since xA+xB = 1 for a binary mixture, your equation
simplifies to xA = xA which is true but of no use to anyone.
Your terminology
is nowhere explained, so again, that is no use to anyone.
Perhaps you should start with the fundamental definition of xA and xB in terms of molar quantities nA and nB in the liquid phase. That might help get us all on the same page.