https://www.thetimes.co.uk/edition/scotland/disused-mineshafts-could-get-new-lease-of-life-as-green-energy-power-stores-877jphrcv

There's loads of smelly old shafts in Middleton (Youlgreve, Derbyshire) which they can have, horrid bad air!

if you search for Gravitricity then there are many other websites which don't require you to sign up to read their twaddle!

"require you to sign up to read their twaddle!"

Whoops sorry, I copied the link from the logged in side of my college Times account without realising it has a paywall.  :spank:

Great I idea I think.  Much like Dinorwig pumped storage hydro station in Wales. Only runs at times of peak demand and helps enormously with National Grid demand management.

I imagine the very deep coal mining shafts are more suited to this kind of application.

Hmm...  How much energy could be generated in this way by dropping cavers down Gaping Gill on a winch meet?

I suppose you'd need it all for pulling 'em back up again afterwards, though.

Most disused mineshafts would carry heavy hydraulic damping.....

SamT said:

Great I idea I think.  Much like Dinorwig pumped storage hydro station in Wales. Only runs at times of peak demand and helps enormously with National Grid demand management.

I imagine the very deep coal mining shafts are more suited to this kind of application.

Click to expand...

Almost certainly going to be the very deep shafts.

For the weight on their website they are talking about 3,000 tonnes - which even if you got a 2 metre wide cylinder of lead would still have to be more than 80m long - so definitely looks suited to a v. deep coal mine, rather than a traditional Derbyshire lead shaft, where it would bottom out before it got going - or you'd have to substantially reduce the size of the mass and hence the generating power.

If you dropped 3,000 tonnes down a mile-long shaft with enough resistance to take 1 hour to reach the bottom, that could generate about 13MW in theory, which is good, but you'd need quite a few of them to match the Dinorwig plant, which can produce 1800MW for up to 6 hours.

Good job there are lots of deep unused shafts about, though I'm guessing a large proportion are now flooded.

Ah Yes, Long shaft Depths

Gravitricity said:

Shaft depths can be from 150m for new shafts down to 1500m for existing mines.

Click to expand...

I would like to know how much power they're going to use to keep (pump) the Shaft(s) dry to a depth of 1.5km...

Why pump the shaft dry?
If steel is used for the weight then buoyancy would only reduce it by about 13%.
Viscous damping would be greater of course, but the thing would be moving quite slowly and I imagine it would not be a close fit.
Come to that, why not have several (on guide wires fixed to the sea bed) dangling below a vessel in a nice deep Norwegian fjord, or even the deepest part of the N sea (up to 600m I think). I believe nowadays they can keep vessels very accurately in the desired place using satellites and thrusters?
The supply cable would need looking after of course.

On a more practical level, I struggle to understand how the generation side would be controlled:
with the mass falling at a steady speed and generating electrical power, if the electrical load is increased (say by switching another street onto it) then the mass would need to fall faster to meet demand, but in fact the reverse would happen.
Somebody please tell me where I am going wrong.

Chocolate fireguard said:

On a more practical level, I struggle to understand how the generation side would be controlled:
with the mass falling at a steady speed and generating electrical power, if the electrical load is increased (say by switching another street onto it) then the mass would need to fall faster to meet demand, but in fact the reverse would happen.
Somebody please tell me where I am going wrong.

Click to expand...

The obvious way would be to have lots of these and switch them on or off as desired to balance supply. Small fluctuations in supply vs demand are balanced by the grid in small frequency fluctuations.

why not just use the " off peak power surpluss " - to convert scotlands traditional hydro electric plants to " pumped power systems ???????????????

refilling reservoirs - also allows the water to be used for drinking // agriculture // industry - instead of just run-off to the sea

this shafts and falling masses idea sounds - complex and costly