Mine shaft storage on news

[SamT]

I concede there is nothing wrong with the 'numbers', just using the units in the wrong context (IMHO).

 

[RobinGriffiths]

Would it be better having a ginormous array of enormous flywheels? If the mass was concentrated around the circumference, they needn't necessarily be heavy. Unfortunately, I sold my Kreyszig a few years ago, so without going down various internet rabbit holes I can't give you any 'sums'.

I suppose the advantage of flywheels as opposed to mine shafts is that the energy isn't constrained by depth of your shaft (oo err missus..), but rather combination of mass and maximum rotational speed of your flywheel before it shakes itself apart, although precise manufacturing would ameliorate.

 

[PeteHall]

The trouble with a flywheel is that you are storing kinetic energy, which has intrinsic losses over time.

The beauty of storing gravitational potential energy is that it's just waiting for you when you need it and doesn't diminish over time.

 

[pwhole]

I think this idea is still my favourite of the non-mechanical ideas as it's more or less feasible now, though admittedly expensive to construct. But the science works, and it runs 24/7.

https://en.wikipedia.org/wiki/Solar_updraft_tower

 

[Speleofish]

It's a nice idea but, how efficient is it when compared to a latest generation solar farm?Without doing any maths, I would be concerned that the energy losses incurred in driving the turbine might be excessive. On the other hand, it could be built using relatively simple materials, which might make it viable in the right surroundings.

 

[Cantclimbtom]

I concede there is nothing wrong with the 'numbers', just using the units in the wrong context (IMHO).

Although I'm not defending jumbling units (and I've frequently been guilty of that myself), in this case we'd be wise to think about power output perhaps as equal importance to energy stored. If I could store petajoules of power somehow, but only produce it at 100W nobody would be interested (unless it was a deep space probe)

Another key factor for something like this to be useful to people, is if it can deliver very high power extremely quickly (i.e. go from zero generation to full power in shortest possible time). This is actually bloomin' difficult. I've worked somewhere that needed 2 of the 6 generators (1MW) to be kept spinning at full speed at all times so that they could start generating at the drop of a hat (in addition to 2 different grid connections).  From what I remember doing the Electric Mountain tour some years ago, they do something similar there keeping some turbines spinning, but a bit bigger scale than 1MW

What this bizarre weight on a string approach brings is the ability to let it drop and start generation at peak power

I'm still not convinced this is better than a large garden shed with a bunch of old forklift batteries in it, especially in their promotion waffle where they talk about sinking new shafts to provide storage anywhere (BS!)

 

[Roger W]

It does remind me of the question of how much useful energy cavers could generate when abseiling down potholes if they used the right sort of gear...

 

[royfellows]

Would it be better having a ginormous array of enormous flywheels? If the mass was concentrated around the circumference, they needn't necessarily be heavy. Unfortunately, I sold my Kreyszig a few years ago, so without going down various internet rabbit holes I can't give you any 'sums'.

I suppose the advantage of flywheels as opposed to mine shafts is that the energy isn't constrained by depth of your shaft (oo err missus..), but rather combination of mass and maximum rotational speed of your flywheel before it shakes itself apart, although precise manufacturing would ameliorate.

If the oil supply to a bearing fails, you in big trouble.

I believe that there was some disaster in Russia years ago when just this happened?

 

[nickwilliams]

If the oil supply to a bearing fails, you in big trouble.

That's also true of a gas turbine engine which is now the most common form of fossil fuel generation on the grid.

 

[ChrisJC]

Using power in kW which is a rate of energy use/generation is just nonsensical when talking about energy which is just a quantity.

How much energy can this mineshaft generate.. 27.8 kW

Here's another angle then.

The 10t weight when suspended at the top of the shaft has 100,000,000 Joules of potential energy.

To put that in context, it is about the same as 3 litres of Diesel. A good Diesel engine is 50% efficient, so a Diesel generator would consume 6litres of Diesel to generate the same amount of energy as lowering the weight in a mineshaft.

Chris.

 

[2xw]

It does remind me of the question of how much useful energy cavers could generate when abseiling down potholes if they used the right sort of gear...

You might be better off with engineers and their keyboards 

 

[alex17595]

I've always wondered how much electricity you could generate by digging a new adit and putting a turbine at the lowest level of a flooded slate mine. Some of them must rival purpose built reservoirs for volume of water.

 

[Carbide1]

A lot will depend on the refill rate of the site in question.

 

[Cantclimbtom]

And if you could also harness the energy released by the angry divers somehow, you'd double the generation

 

[sinker]

And if you could also harness the energy released by the angry divers somehow, you'd double the generation

The chest-puffing alone would turn a small wind turbine. Coupled with methane generated from all the bullsh!t. Free power!

 

[ChrisJC]

Coupled with methane generated from all the bullsh!t. Free power!

If methane from bullshit is required, the opinion columns in The Guardian will take some beating...

Chris.

 

[RobinGriffiths]

As indeed would the comments section of the Daily Mail  :tease:

 

[ChrisJC]

As indeed would the comments section of the Daily Mail  :tease:

touche!

Chris.

 

[andrewmcleod]

Ffs, 1 ton is 907.185 Kg!

Bit late to respond, but 1 ton = 1000 kg, unless you are a Yank and want to desperately keep the last dying vestiges of the 'British Empire' alive...

I think we could be a bit more ambitious in terms of weight. Let's assume a ~300m deep mineshaft with a square cross-section slightly larger than 2m x 2m (i.e. a big one? not an expert on mineshafts). If we get a 10m x 2m x 2m (40 cubic metre) concrete weight, it would weigh about 80 tons; if we used steel we could get about 300 tons. That's heavy, but there are plenty of portable cranes that can do that, so shouldn't be a major problem for fixed winching gear.

300 tons * 300m gives you (roughly) 883 x 10^6 J, or 245kWh. Ten such mineshafts would therefore store roughly 2.5 MWh - in other words, they could dump probably 2MW onto the grid for an hour (allowing for efficiency losses), or (probably more usefully) 20MW for six minutes. That's a lot less than Dinorwic (which can do its 2+GWhr for I think 8 hours or so?), but not entirely trivial either. It's probably not enough to absorb any significant amount of excess wind power or similar; it would only be useful for grid balancing. However, it would have the benefit that it would be one of the fastest responding parts of the power grid - even Dinorwic takes most of 20 seconds (I think) to fire up.

If you had a hundred of these mineshafts, you could within seconds have 200MW running for six minutes, which would be long enough to cover the unexpected disconnection of a small nuclear power plant until you can fire up a gas turbine or similar. This is obviously becoming increasingly ambitious for fairly minimal benefit...

Probably it's still a silly idea. But it depends on exactly what it's intended for. And in reality, all that really matters is whether the person building it will make a return on their investment by buying power when it's cheap and selling it when it's expensive.

 

[shotlighter]

Ffs, 1 ton is 907.185 Kg!

Bit late to respond, but 1 ton = 1000 kg, unless you are a Yank and want to desperately keep the last dying vestiges of the 'British Empire' alive...

Er, wrong 1 tonne is 1000kg.
1 ton is 907.185 kg.