
Giant flywheel project in Scotland could prevent UK blackouts - ewood
https://www.theguardian.com/business/2020/jul/06/giant-flywheel-project-in-scotland-could-prevent-uk-blackouts-energy
======
_whiteCaps_
> This is the first time a project of this kind will be used anywhere in the
> world and ESO believes it could be a “huge step forward” in running a zero-
> carbon electricity grid.

I'm trying to find some stats on this, because flywheel UPS aren't a new idea:

[https://www.finning.com/en_IE/products/new/power-
systems/ele...](https://www.finning.com/en_IE/products/new/power-
systems/electric-power-generation/ups-flywheel/18499752.html)

[https://en.wikipedia.org/wiki/Flywheel_storage_power_system#...](https://en.wikipedia.org/wiki/Flywheel_storage_power_system#Power_grid_frequency_control)

~~~
Ballas
What is different in this case is it is not really an energy storage system
(at least that is not the main intended purpose), but only to provide
stability to the grid frequency. A huge flywheel in a vacuum to provide a
reference to millions of distributed PLLs. I don't think the idea is to always
have it spin at a fixed rate with minimal losses.

In the case where a flywheel is used as a UPS, the rate at which it is
spinning will vary in accordance with the stored energy.

~~~
tankenmate
You can get constant spin rate but variable energy storage / release by
adjusting the moment of inertia, e.g. if you have movable weights within the
rotor you can move these inboard or outboard, moving it inboard uses energy
while increasing the spin rate, and moving it outboard releases energy while
slowing the rate. Using this in combination with "conventional" direct axle
energy input / release means you can store or release energy from the system
as a whole while also keeping a constant rate (within the bounds of the total
energy storage capacity of the system).

~~~
neltnerb
Is this used in practice? It sounds like a rather substantial engineering
challenging considering how much energy the wheel is storing. I remember MIT
had one of these for sparking the old tokomak, they had to plan for it to fall
off, destroy several buildings without killing anyone, and then land in the
river... and that was a solid wheel that did nothing but spin.

But isn't the point that it provides inertia towards stabilizing the
frequency? I don't think it matters whether you can vary the energy stored if
it's just acting as a, well, wheel... if the goal is to give you a bit more
time to bring more generation online or take it offline then it seems like a
simple system would be fine. It's not storing power, so it can only ever slow
the drift to give more flexibility.

~~~
tankenmate
As you say, I suspect it probably isn't used much in grid scale applications.
The device image in the article would imply that it is just a simple damper,
i.e. the angular momentum acts to reduce any frequency change, up or down. It
doesn't look like it does any storage, but then the article is somewhat
content free.

~~~
mrow84
What you are describing is essentially a centrifugal governor:
[https://en.wikipedia.org/wiki/Centrifugal_governor](https://en.wikipedia.org/wiki/Centrifugal_governor),
I think?

------
MrBuddyCasino
Those things have interesting failure modes. Will they have to be buried
underground, or is this somehow a solved problem?

~~~
tpmx
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](https://www.youtube.com/watch?v=bdcE3VyKv5U)

~~~
msandford
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 power.

If I understand correctly the idea is a lot like capacitors for DC voltage.
The DC voltage has to go down in order for the capacitor to supply current,
but the capacitor ensures that the voltage can't go down as quickly as it
would otherwise.

~~~
MrBuddyCasino
Thats not the theoretical limit though. This is a physical device with moving
parts. What if the bearing fails? What if the weight disintegrates due to a
manufacturing fault?

Suddenly all that stored energy wants to go somewhere.

~~~
opwieurposiu
The flywheel will have breakers to prevent excessive inflow or outflow of
power.

In a conventional plant, the spinning machinery is monitored by vibration
sensors. If the vibration exceeds some threshold, a "Turbine Trip" occurs and
the offending generator is disconnected from the grid. It then slowly spins
down, dissipating energy via it's own friction.

[https://en.wikipedia.org/wiki/Turbine_trip](https://en.wikipedia.org/wiki/Turbine_trip)

------
kwhitefoot
Does anyone have any real information about this project? The Guardian article
is essentially the same as the press releases on both GE's and Statkraft's web
sites and says nothing about the scale of the project.

~~~
yummypaint
They say it's a 25M pound budget, and show a model about 2x the height of a
person, so it looks like it may just be that single unit. The moment of
inertia looks comparable to that of a large steam turbine.

------
jeffbee
This discussion of a test flywheel installation in California seems a lot more
interesting than this article.

[https://ww2.energy.ca.gov/2019publications/CEC-500-2019-012/...](https://ww2.energy.ca.gov/2019publications/CEC-500-2019-012/CEC-500-2019-012.pdf)

~~~
ansible
Thanks for the link. It is heartening to see utility-scale storage for a
reasonable cost being developed.

20 years ago, there were a couple companies working on flywheel energy storage
for mobile applications. They were using carbon-fiber flywheels, which could
spin up to 100K RPM, but were expensive to manufacture. I would have predicted
(back then) that carbon-fiber would have won out eventually for infrastructure
applications as well, but I guess they were not able to get the costs down
sufficiently.

------
jeffbee
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.

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

~~~
jeffbee
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.

------
DrBazza
This is a consequence of the UK having little capacity for pumped-storage,
i.e. hydro-electric. We don't really have the height, and we have "areas of
outstanding natural beauty" that cannot be built in easily, so we need
alternatives to store the energy.

The rest of the world just builds a dam, creates a new lake, and moves on.

~~~
frobozz
Cofiwch Dryweryn!

~~~
rbanffy
And people say Hungarian is hard...

~~~
_sbrk
Lol. Reminds me of The Crown where Price Charles is learning Welsh.

However, at least all the letters are familiar. Asian languages are at least
an order of magnitude harder for westerners.

~~~
rbanffy
In Irish, at least, the letters being familiar doesn't help when they sound
totally different.

When I moved here, I arrogantly stated I was going to learn Irish. I'm humbled
now.

------
ggm
This sounds like a fancy syncon. They have been a thing in power network
engineering for a long time.

I can believe it has "new features" but the underlying mechanics of a Syncon
are not new. This may just be something good, being over sold by a company
with an interest in boosting.

~~~
sova
This looks like the electrical equivalent of a weir

------
verytrivial
[https://www.goodnewsfinland.com/teraloop-secures-
eur-2-4-mil...](https://www.goodnewsfinland.com/teraloop-secures-
eur-2-4-million-grant/) \- There's a Finnish company called Teraloop who've
been chipping away at a more Sci-Fi version involving maglev and evacuated
loops.

Life gets difficult for this model because the heat induced due to current
'turbulence' and maybe skin effect gets 'stuck' inside the chamber. Fun
engineering problems.

~~~
Someone
Even more Sci-Fi (I think; I couldn’t find definitive figures as to the size
Teraloop aims for): [https://www.ecn.nl/news/item/floating-train-at-2000-kmh-
set-...](https://www.ecn.nl/news/item/floating-train-at-2000-kmh-set-to-
store-10-of-dutch-electricity/). I don’t know whether that idea died on the
drawing table since 2015, but I guess it could have.

------
xhkkffbf
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.

Or am I wrong?

~~~
URSpider94
In the electrical grid, frequency is proportional to voltage. When the
frequency drops, it means that the supplied voltage is also falling. Likewise,
if you go over-frequency, then the voltage will rise.

Traditionally, the inertia of thousands of tons of spinning generator turbines
across the system provided this inertia, but with more and more nonlinear
sources (and also nonlinear loads), that balance is disappearing.

~~~
jillesvangurp
Batteries are also becoming popular for the same reason. The more batteries
you have the easier it is to deal with fluctuations in supply and demand as
you can switch them on and off in milliseconds and they can serve to both
supply GW to the grid or absorb it from the grid.

Flywheels are useful because they store a lot of energy and don't require a
lot of energy to keep them spinning (i.e. topped up with energy). Simply
connecting them to a generator can be done (relatively) quickly and allows
them to supply power for a relatively long period of time. It's basically a
mechanical battery.

Both have the advantage that they are cheaper to operate than a typical peaker
plant, which is increasingly the role of remaining coal plants that are
otherwise too expensive by orders of magnitudes to operate continuously.
Switching those on is a last resort for energy companies. The more battery
they have, the less need they have for those. And the less they get utilized,
the more expensive they are to keep around. Gas plants are better but they
take a long time to turn off and on again and doing that is also not cheap.

Prices have actually turned negative a couple of times in e.g. the UK in cases
where the power companies were literally paying people to use their excess
power just so they could avoid having to turn off plants that are expensive to
turn back on. Basically, grid storage capacity allows electricity companies to
smooth out peaks in demand and supply and respond extremely rapidly by either
soaking up or supplying many GW.

~~~
M2Ys4U
Also worth noting:

We haven't even burned coal for the purposes of providing power[0] since the
11th of May. That's the longest period without coal being burned since 1882.

[0] Sort of. A couple of coal plants underwent maintenance and had to be fired
up and provide power to fully test them. We had a total of around 21 hours of
coal plants supplying energy and we're now at day 18 of a coal-free run, and
prior to the test we had almost 68 days!

------
sixhobbits
I don't really know a lot about energy. Is this similar to something like
Energy Vault[0] or is stabilizing the frequency different to storing power for
later use.

[0]
[https://www.youtube.com/watch?v=gn5AM75AGvw](https://www.youtube.com/watch?v=gn5AM75AGvw)

~~~
LordHeini
This energy vault device will not work for a couple of reasons. Like the
astonishingly low energy density of such a structure or the difficulty in
running and maintaining the cranes to pull the weights. It is basically a
mechanical version of pumped hydroelectric energy storage; just clunky and
inefficient.

Flywheels store orders of magnitude more power per ton and have very low
reaction times (in the order of milliseconds).

This makes them great for frequency control which just means really short term
energy storage.

The power grids frequency is directly co-related with the power throughput. If
there is too much demand the frequency will drop.

A flywheel can quite easily buffer very short term demands and flatten the
somewhat erratic output of wind turbines or solar.

------
cordite
How big and how fast must a flywheel be to perturb Earth's rotation, in a
similar method of
[https://en.wikipedia.org/wiki/Control_moment_gyroscope](https://en.wikipedia.org/wiki/Control_moment_gyroscope)

~~~
ricardobeat
The rotational energy of the planet is absolutely massive. I don't remember
the numbers but you'd need _millions_ of atomic bombs fired at once just to
make a dent - and it would still not affect the orbit of this now radioactive
fireball at all.

------
BTinfinity
Wasn't aware blackouts were a significant problem in the UK. Great device for
moving away from fossil fuels though

~~~
rcxdude
They aren't particularly, but there was a fairly large one last year, and grid
stability is become harder as more and more of its energy comes from
renewables (as the article mentions, the grid is favoring fossil fuel power
sometimes in order to keep things stable).

~~~
DrBazza
This might interest you:

[https://www.ianvisits.co.uk/blog/2019/12/10/watch-a-power-
st...](https://www.ianvisits.co.uk/blog/2019/12/10/watch-a-power-station-
demolition-2/)

"The power plant was notable for being one of the few that could restart
generating electricity without an external power to restart its generators in
case of a wide-scale power-outage. This was partly due to cold-war concerns
that an attack could take out London power supplies.

To be able to restart the plant, it made use of versions of jet engines based
on those used on Concorde to jump start the main generators — and they were
used to keep the lights on following the October 1987 storms."

------
geogra4
well, assuming scotland doesn't leave...

~~~
rbanffy
The United Celtic Republic of Scotland and Ireland (and Wales?) will be more
than happy to export angular momentum to its less enlightened neighbors.

------
yboris
Feels like friction would eat away a lot of electricity, no?

~~~
lolc
Flywheels (no matter their size) can be operated in near vacuum with magnetic
bearings[0]. Friction can be really low. A funny aside is that they have to be
aligned with earth's rotation so they don't resist it.

[0]
[https://en.wikipedia.org/wiki/Magnetic_bearing](https://en.wikipedia.org/wiki/Magnetic_bearing)

~~~
yboris
Thank you for the response.

My thought is that the weight of the flywheel matters. To be able to absorb /
release a tremendous amount of power, I imagine this flywheel would need to be
very heavy. If so, wouldn't it non-linearly differ in efficiency from the near
vacuum & magnetic bearing designs we've built before?

Perhaps the proposal is to build a large array of smaller flywheels that don't
have to deal with the problem I imagine?

I'm not familiar with any part of engineering here -- just a curious soul --
sincerely asking!

~~~
lolc
Not that I know much about flywheel engineering. But machines tend to become
more efficient the bigger you build them.

With flywheels, I don't see the bearings as difficult. I mean it's sure a
challenge to keep a few tons afloat, but nothing unsolved. I'd assume (but
don't know) that you can scale magnetic bearings a few orders of magnitude
with their properties staying the same.

On the other hand, the faster you spin flywheels, the more energy they store.
And here comes the limitation: The material they're made of has to sustain all
tearing force. So at some point you'll add mass instead of spinning faster.

------
bArray
> will not generate electricity or produce carbon emissions

There is still a tonne of carbon used in creation...

~~~
epx
Certainly less than 1/100 second of daily global emissions?

------
hindsightbias
Haven't these been around forever? I went on a tour of a university tokomak in
the 80's and they had some giant flywheel for short-burst electrical energy.

------
catalogia
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.

~~~
Ballas
It is to mimic the spinning turbine generators, which themselves act as
flywheels, but in this case without the turbine part. The rotational inertia
gives stability in that the frequency cannot suddenly change. I thought that
was quite clear from the article?

~~~
catalogia
The article isn't unclear, it's just weird. Smoothing out the input power is
doubtlessly the most common purpose of a flywheel, second to power storage,
and both of those is what this flywheel is for too. Describing a flywheel in
terms of a turbine due to turbines acting as flywheels is the part that's
weird.

~~~
happytoexplain
As somebody without the domain knowledge, I thought the article did a great
job of making it clear what the flywheel is doing (though of course it could
be misleading in some way and I wouldn't know). I'm honestly a little confused
as to the nature of your objection about which object is described in the
context of the other.

~~~
catalogia
I'm not 'objecting' to anything and I don't think it's misleading. I just
think it's weird to describe a simple machine in terms of a more complex
machine by pointing out that in one aspect the more complex machine is doing
what the simpler machine does.

It's like describing a light-switch in terms of relays. Not wrong, not even
misleading, but normally you'd expect the comparison to be made the other way
around; describing relays in terms of light-switches or the rotational inertia
of turbines in terms of flywheels.

------
geocrasher
Same article, no registration required. This site touts "Powered by The
Guardian" and does not appear to be a scraper:

[http://www.execreview.com/2020/07/giant-flywheel-project-
in-...](http://www.execreview.com/2020/07/giant-flywheel-project-in-scotland-
could-prevent-uk-blackouts/)

~~~
netsharc
Looks like a content-stealing site thinking adding a PNG that credits the
original source is enough to keep them away from trouble...

The Guardian's registration nag keeps getting worse and worse, but there is
still a button labelled "Not now" to bypass it.

~~~
empyrical
It's from the Guardian Open Platform[1], which has a clause in the TOS[2]
requiring that that the "Powered By The Guardian" logo be displayed where you
display Guardian content

> Include a "Powered by The Guardian" logo (or such other Guardian logo as we
> may require from time to time) on the same webpage as any republished OP
> Content, or any tool or function that is based on OP Content. Such logo must
> be a reproduction of the "Powered By" file found at
> [http://www.theguardian.com/open-
> platform/logos](http://www.theguardian.com/open-platform/logos), and comply
> with any special terms set out by us. The "Powered by The Guardian" logo
> must not be used in conjunction with any content other than the OP Content.

[1] [https://open-platform.theguardian.com/](https://open-
platform.theguardian.com/)

[2] [https://www.theguardian.com/open-platform/terms-and-
conditio...](https://www.theguardian.com/open-platform/terms-and-conditions)

