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Giant flywheel project in Scotland could prevent UK blackouts

theguardian.com

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Re: Giant flywheel project in Scotland could prevent UK blackouts

#101

Post by generatorguy »

craftinator wrote: post #80
TremendousJudge wrote: post #68

Earlier quoted context omitted.

How much mass are we talking about here? I'm curious and the article doesn't give any numbers. Order of magnitude at least?

I'm curious about this is well. I imagine it must be huge to handle the scale of the grid!

Rotational energy goes up worth both the square or the radius and the speed, so it is much better bang for your buck to have a the mass centered on an outer rim connected to a hub by spokes and spinning really fast rather than just something uniformly heavy. The mass close to the centre doesn’t do anything for you.

The heavier it is also requires bigger more expensive bearings and accompanying system to get the thing spinning in the first place.

I looked at a flywheel that spun at 12,000 rpm. It was going to be located in an underground vault in case it ever got off its pedestal bearings it wouldn’t mow people down.

Like anything that stores energy but doesn’t generate the economics aren’t great.

Re: Giant flywheel project in Scotland could prevent UK blackouts

#103

Post by Johnythree »

msandford wrote: post #42
tpmx wrote: post #39

Earlier quoted context omitted.

What happens if the grid frequency disagrees too much with the rotation frequency of the flywheel, too quickly? The flywheel disintegrates and turns into a massive spherical weapon of mass distruction? Like this, but 20x worse? https://www.youtube.com/watch?v=bdcE3VyKv5U

The spinning flywheel doesn't just spin on its own. It gets spun up and kept spinning by an electric motor/generator I have to imagine. So you're limited as to how much power can go in or out by the size of that motor/generator. If it's a 100kw peak electrical machine then it can provide at most 100kw of instantaneous power to the grid while at the same time slowing down by however much is required to deliver that po…

No.

It's a synchronous motor which normally idles at the Mains frequency, but if the Mains frequency attempts to change, the rotor inputs massive amount of current (leading or lagging) into the mains which prevents the change.

There is no need for a drive motor.

In the industry they are known as a "Synchronous Condenser" or Syncom. They have been in use for a long time.

https://www.pv-magazine-australia.com/2019/04/06/long-read-b...

Re: Giant flywheel project in Scotland could prevent UK blackouts

#105

Post by Johnythree »

ladberg wrote: post #69
tpmx wrote: post #62

Earlier quoted context omitted.

Sorry, but this comment shows that you don't understand the physics that would be involved in something like this.

I think you're misunderstanding how this flywheel operates. It doesn't provide 50hz AC in the same way the grid operates, it just is attached to a DC motor that provides electricity which can then be converted into AC to power the grid. That means it can spin at any frequency and it doesn't really matter what state the grid is in.

Completely wrong.

It's a synchronous rotor which is spun by the mains. When the mains frequency tries to change, the momentum of the flywheel supplies massive leading or lagging current to prevent the change.

It behaves exactly as an un-powered generator idling on the mains.

There is no DC motor.

In the industry they are known as a "Synchronous Condenser" or Syncom. They have been in use for a long time.

https://www.pv-magazine-australia.com/2019/04/06/long-read-b...

Re: Giant flywheel project in Scotland could prevent UK blackouts

#106

Post by Johnythree »

jeffbee wrote: post #48

Does it make sense for a flywheel to have a horizontal axis of rotation, as shown in the concept image? Seems like that would be the hard way, from the standpoint of engineering.

It's axis must be parallel with the Earth's axis, otherwise the earth's rotation would generate enormous gyroscopic forces.

Re: Giant flywheel project in Scotland could prevent UK blackouts

#107

Post by Johnythree »

catalogia wrote: post #6

Framing a flywheel as a "simulation of a turbine" is really bizarre, unless there's something quite weird about this particular flywheel that the article fails to make clear.

It behaves exactly as an un-powered (but spinning) generator.

In the industry these are known as a "Synchronous Condenser" or Syncom. They have been in use for a long time.

https://www.pv-magazine-australia.com/2019/04/06/long-read-b...

One problem with the switch to renewable energy is that the mechanical momentum in steam turbines is lost.

This leaves the grid vulnerable to rapid changes in loading.

Re: Giant flywheel project in Scotland could prevent UK blackouts

#108

Post by jeffbee »

Johnythree wrote: post #106
jeffbee wrote: post #48

Does it make sense for a flywheel to have a horizontal axis of rotation, as shown in the concept image? Seems like that would be the hard way, from the standpoint of engineering.

It's axis must be parallel with the Earth's axis, otherwise the earth's rotation would generate enormous gyroscopic forces.

Interesting. Why does every other flywheel on the market have a vertical axis (that is, normal to the surface of the Earth, regardless of the place it is installed)?

I was thinking more about the fatigue of the shaft.

Re: Giant flywheel project in Scotland could prevent UK blackouts

#109

Post by rcxdude »

xhkkffbf wrote: post #32

Why do we care about keeping frequency stable when more and more products simply put the power through a rectifier to turn it to DC? The lamps all have LED "bulbs". The computers have power bricks. Do we really care if the compressors in the air conditioners and the refrigerators turn at a slightly different rate? Okay, maybe a rapid shift in frequency could be damaging, but a slight drift sounds okay mechanically. O…

The frequency of the grid is a strong indicator of the balance between supply and demand. If it has drifted off by even a small amount the system is close to a runaway collapse (modern switch-mode power supplies are actually quite bad from this point of view: when the voltage drops their effective power draw actually increases, in comparison to a lightbulb or traditional motor). And when the system collapses in an uncontrolled way it can quite easily cause severe damage to generating equipment which will take it offline for a long time. So there's a lot of stuff which goes into cutting out load and/or generators before bad stuff happens, and it tends to err on the side of caution, because a 1 hour blackout is far better than a significant amount of generation capacity being offline for months.

Re: Giant flywheel project in Scotland could prevent UK blackouts

#110

Post by epistasis »

ascorbic wrote: post #71
epistasis wrote: post #54

Earlier quoted context omitted.

Hydro storage and flywheel storage have very different use cases, typically. Flywheels contain tiny amount of energy, but can respond nearly instantaneously To provide frequency regulation on the grid. Hydro has massive amounts of energy storage (days+ worth of output), but takes a looot longer to respond than flywheels. I think we will see very little flywheel or dam construction in the coming decades; battery stora…

Hydro can be fast. The UK uses pumped hydro for frequency management among other things, and can spin up several GW in seconds.

Oh interesting! I had heard of some hydro in the US planning to instal batteries to help with faster response. But I guess there is great variety in design.
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