Pumped-storage hydro dam schemes to store wind energy (Scotland)

[Peter Dow]

No Doubt the concept works , Otherwise SSC

SSE.

would not want to build their project in the first place . To make your project bigger , does not mean its better.

Doesn't mean it is worse either. You need to look at the details to decide, better or not?

But no doubt they have crunched all the numbers to come up with that project.

No doubt the SSE crunched their own, electricity supply business numbers.

The numbers I am crunching are for the country, for our economic future, with a goal to supply power from renewables alone. So those are different numbers and they crunch differently. I am not expecting the SSE to fork out £20 billion they don't have. This is a national project driven through by government I am proposing.

The key to the whole project is the "cheap off peak power " is the key to it .. If that power is not available in the quantity needed .You have a Giant White Elephant on your hands .

Well it looks like wind power will eventually provide all the cheap off peak power to top up a massive pumped-storage scheme. We need to look ahead, plan for the future, for the future wind turbines, not for the limited numbers we have today.

[Peter Dow]

Reservoir induced seismicity

That system is in wide spread use,

All of them use pumped-storage hydroelectricity when they put the kettle on after the TV soap finishes, yet some of them even deny it exists.

but like I said earlier it is a store of energy to allow for generation at peak times then uses cheaper off peak energy to replenish the upper loch.

Right. The difference in future is that there will be a lot more off peak energy available than there was in the days before wind farms.

the weight of water can cause earth quakes as has happened in China and south America.

This is an issue of wide concern so I think it is worth discussing for more reasons than just my scheme for Coire Glas.

Here in Canada and especially so in the provinces of Quebec and Manitoba we have lots of hydro electric power, some of the biggest dams in the world are the James Bay Project in northern Quebec where they have experienced small earthquakes because of the weight of the water on the land and this in an area of Canada with the least seismic activity.

It's an issue for deep reservoirs everywhere but we'll do better if we understand that the seismic effect comes from the water pressure rather than its weight. Those of you with experience in plant and construction will all know how hydraulic fluid moves the joints of construction machines. There it is the pressure of the hydraulic fluid, not really its weight which does the work.

This is why deep water can do much more seismic damage than the same weight of rocks. It is not really the weight of the water on the top of the reservoir bed that does it. It is more an effect of the pressure of the deep water that gets down into fractures in the bedrock, the cracks, or the fissures, to exert a splitting force inside the rock, to force those cracks open wider, to bring force against the rock where it is weak, in tension.

If it was just the weight of water then the same weight of rock would do the same seismic damage but it doesn't. The hydraulic pressure of water does the real damage. Sometimes this effect can be very useful such as in the oil and gas business as described here.

Wikipedia: Hydraulic fracturing

Also some geothermal power stations use the same effect.

So that's the science. So what do we do about the issue, engineering wise, for deep reservoirs, or is increased seismic activity unavoidable? Well here's my take on the issue.

Reservoir bed drain

The high pressure of water which is deeper than 100 metres has the potential to induce seismic activity or earthquakes in susceptible rock in which a new reservoir has been constructed.

Wikipedia: Induced seismicity - Causes - Reservoirs.

The mass of water in a reservoir alters the pressure in the rock below and through fissures in the rocks, lubricates the fault, which can trigger earthquakes.
...
Unfortunately, understanding of reservoir induced seismic activity is very limited. However, it has been noted that seismicity appears to occur on dams with heights larger than 100 meters. The extra water pressure created by vast reservoirs is the most accepted explanation for the seismic activity.

Coire Glas/SSE/92 m

Hopefully, reservoir induced seismicity was an issue considered by the SSE when selecting Coire Glas for their hydro dam project.

I am speculating that this issue may be why the SSE have limited their dam to a height and their reservoir to a depth of 92 metres?

I would note however that the pressure in the head race tunnels which supply water from the reservoir to the turbines would be proportional to their depth below the surface of the reservoir and this could be as much as 500 metres deep, so there would seem to be some potential for water to penetrate the bed rock from the high pressure water tunnels and induce seismic activity even in the SSE case.

This is an issue which ought to have been addressed in the many previous pumped-storage hydro scheme projects, most of which seem to have a difference in head of more than 100 metres.

Given that "understanding ... is very limited" according to Wikipedia, though, I do wonder if the reservoir induced seismicity issue has not always been properly addressed in all previous dam and reservoir construction schemes where the great depth of water and susceptible geology ought to make it a relevant concern?

Coire Glas/Dow/317+m

I am proposing measures to counter the reservoir induced seismicity effect in the case that the geology of Coire Glas is susceptible to it and in the general case.

I propose the construction of a large reservoir surface drain to cover the whole reservoir bed and the reservoir sides too to try to stop the penetration of water under high pressure into fractures in the bedrock and so thereby stop this high pressure water from widening and extending bedrock fractures.

To illustrate my "reservoir bed drain" concept, I have drawn a diagram comparing the usual no drain on the left, with my proposed reservoir bed drain and dam drain pipes on the right.





Image also hosted here.

So my idea is that the top layer of the bed drain is as impermeable as practical, using perhaps a layer of reinforced asphalt concrete.

In engineering practice I believe that impermeable reservoir bed layers have used clay or clay with asphalt or even rubberised asphalt mixed with sand.

My basic idea is to construct an impermeable layer and to use whatever material is best for that.

Then working downwards, the permeable bed drain layers are increasingly bigger loose particles, with sand at the 2nd top then beneath that grit, then gravel, then small stones and finally below all those a layer of large stones.

The higher layers support the top impermeable layer which is under high pressure from the reservoir water and the lower permeable layers provide many small channels for any (hopefully tiny amounts of) water which forces its way through the supposedly impermeable top layer to drain down the slope of the reservoir bed to the base of the dam and then out under the dam through drain-pipes built into the base of the dam.

The bottom layer of the bed drain is another impermeable layer to try to make doubly sure that the relatively low pressure water that gets into the bed drain will find its way out through the dam drain pipes by following the course of the drain.

These kinds of layers of different sized loose particles have previously been used to make simple narrow drains and impermeable layers have been added to reservoir beds before now but whether professional dam engineers have ever covered the entire reservoir bed and sides with one large drain I don't know. If not, this could be named the "Dow drain" solution to reservoir induced seismicity!

Why not add a simple impermeable layer to the reservoir bed?

I think the additional complexity and expense of a bed drain (and drains for the sides too) is better than simply adding an impermeable layer.

Consider the fault condition of the two possible solutions.

If a simple impermeable layer fails, if it cracks or ruptures or disintegrates under the pressure changes, how would anyone know? It may look fine but be leaking high pressure water into the bedrock and inducing seismicity which OK the engineers would notice any earthquakes but so would everyone else, the earthquakes could cause damage or loss of life and it could lead to a loss of confidence in the project and in the engineers who built it. They could go to jail!

If the top impermeable layer of the bed drain fails then there would be some water pouring out of the drainpipes through the base of the dam when at most it should only be a tiny trickle of water. So the engineers would know there was a problem with the bed drain and they'd know to drain the reservoir and fix or replace the top supposedly "impermeable" layer, fix the bed drain so that it operated as it should.

So failure with the bed drain is noticed right away and it is not a catastrophic failure. Whereas failure with the simple impermeable layer may not be noticed until a catastrophic earthquake happens.

So this is why I think the bed drain is worth the extra complexity and expense. It is a more fault tolerant engineering solution.

[Peter Dow]

So I should have expanded on my idea but I got interrupted last night

Ok this plan refers to Scotland as we are an Island (of sorts )

Well I like original plans, even daft ones, Muz and I'm not just saying that because you are the admin here.

What we need is a massive pipe that connects the west coast to the east coast,

From the Forth to the Clyde? Would it have to be a pipe, or could it be a canal and a underground tunnel?

and because of the tidal variance between the two coasts, you would have a constant difference in water levels of some 4 - 5 meters perhaps more,

Where's your evidence for those figures?

Oh I don't doubt there are tidal flows east <-> west because after all, the potential for tidal power in the Pentland Firth (that's between Orkney and the mainland) is well known.

Wikipedia: Pentland Firth - Tidal Power

But what makes you think the difference amounts to as much as 4 to 5 metres and is "constant". Surely there are times every six hours when the tides change direction when there is no difference and no flow east-west?

and this constant change would be able to drive some sort of turbines without any need for power recuperation. I'm sure you could select the most differentiate points to gain the biggest tidal surge advantage, but its an endless form of enery, day or night, rain , hail, wind or snow.

Do you have any idea how wide a bore of "pipe" you would need and how much water flow you would expect to get and how much energy you would expect to generate?

Why not exploit the Pentland Firth first before seeing if we need to build your "pipe"?

[B4D2USA]

Pumped-storage hydroelectricity is used now and no-one thinks it is a "perpetual motion machine" and only confused people like you think anyone does think it is such a thing. Please get yourself a basic education about it from Wikipedia: Pumped-storage hydroelectricity
and stop assuming if you don't know about it, it doesn't exist or it doesn't matter if it does exist. Many important facts about this world you have still to learn.



OK I see you did not watch this video, or if you did you were not paying attention. Watch it again.


Note how the pumped-storage hydro dam supplies power when the wind is becalmed.

Heh heh heh... Got you goat did I? No need to assume I have no education Peter. And no need to assume you are undeniably right. There are some wonderful ideas here, and not all of them are yours. You do seem to be spending quite a bit of effort trying to sway the local vote. Mine doesn't count, (I'm a Yank), but I still can comment. If my educated comments rile you, what will you do when you go before the powers that be? There will be many more skeptics there than here.

[Wee Jim]

No doubt the SSE crunched their own, electricity supply business numbers.

I think that SSE will have crunched there own numbers but also as part of the national grid they will have crunched numbers to see how much electricity they need for customers and how much theyn can sell to the national grid. I think you would be better trying to work with the SSE than trying to go against them as after all they have experiece in this type of project and you have none.

I truely belive that you really are a very clever man, but with no experience, qualifications in these areas no involvement in these areas and no money to invest then you really are pissing into the wind.

I also think that IF you go to present this 'vision' to the powers that be. The chances are they will already have had encounters with you in the past and shall pretty much have made up their minds and decided they will stamp rejected onto your proposal due to your history in politics. Your best bet would be finding someone to deliver your presantation by proxy or using a front man. I am sorry but i feel that would be your best chance.

Lastly let me congratulate you on your passion and devotuion to this. Maybe i am alone in thinking the following but I think that someone with your drive would be better off focusing your attention at a job or small business rather than wasting your time with your politics and 'visions' as you certainly have alot of drive!

[Stock]

http://en.wikipedia.org/wiki/Vajont_Dam

Mr Peter have a read of this and if you get a chance keep an eye out for it on National Geographic channel might give you a better understanding of why the geology is of such a dam is important, it makes your drainage plan a bit mute..............30 million tons of water travelling at 140 km...........does a lot damage.........

[Peter Dow]

Thanks to B4D2USA & Wee Jim for their comments.

http://en.wikipedia.org/wiki/Vajont_Dam

Mr Peter have a read of this and if you get a chance keep an eye out for it on National Geographic channel might give you a better understanding of why the geology is of such a dam is important,

I had actually read about the Vajont Dam disaster and many others recently as part of my research for my proposal.

The Vajont Dam was always a disaster waiting to happen because the dam was built at a location surrounded by steep unstable, landslide-prone slopes which were known about, warnings were given about, but the warnings were ignored.

My proposal is to have no unstable slopes with no possibility of a landslide occuring. As I wrote earlier

The shape of the perimeter of the excavated reservoir bed is not absolutely critical. So long as it ends up as a stable wall or slope, however it is shaped by the blasting, it will be fine.

What I mean by "stable" is not collapsing even if subject to a once in 10,000 years earthquake of magnitude 7.1 on the Richter scale. So there is just no reasonable possibility of a landslide in my scheme.

it makes your drainage plan a bit mute

No it doesn't. My reservoir bed drain plan is to prevent reservoir induced seismicity. It has nothing to do with steep unstable, landslide-prone slopes above the Vajont reservoir causing a disaster.

A stable slope does not collapse with heavy rain or with earthquakes.
An unstable slope can collapse with heavy rain or with earthquakes.

The difference is in the stablity of the slope. So you should ask - what is the slope made of, solid rock or loose stones? How much rock is above the reservoir when full which could fall into the dam - a lot, or not much? What degree is the slope - gentle or steep?

You are not asking those questions about the two sites and just assuming it is similar when it is nothing of the kind.

So you are confusing the two quite different sites and trying to draw a lesson from one to apply to, what, all deep dams, maybe? It is hard to work out what exactly you are saying because you are being so vague.

To be honest, you sound like Private Fraser in Dad's Army - "The dam is DOOOOMED!"

Note - not all deep-reservoir dams have been closed down and emptied - just the Vajont Dam because it was built at an unsuitable location.

If two situtations are very different you can't logically draw a conclusion from one about the other.

And here we are discussing different dams, different geologies. One, Vajont, with a steep unstable slope above the full reservoir and above the dam, and the other, Coire Glas, with no steep slope above the full reservoir or above the dam.

So it's different. Not the same.

If you want to shut down all deep dams in the world - on you go and see how far you get - but please don't bother us here with your daft plan to close down all deep dams in the world.

..............30 million tons of water travelling at 140 km...........does a lot damage.........

Yes it would but that has nothing to do with my proposed scheme for Coire Glas.

1. There would be more water in my reservoir when full - up to 400 million tonnes of water.
2. None of that water is going to over-top the dam. It's not going anywhere except through the tunnels to the turbines.

Now actually, nuclear weapons can do far more damage than water sitting in a reservoir created by a dam - but so long as both are under good control there's no need to panic.

[FnDaily]

http://en.wikipedia.org/wiki/Vajont_Dam

Mr Peter have a read of this and if you get a chance keep an eye out for it on National Geographic channel might give you a better understanding of why the geology is of such a dam is important, it makes your drainage plan a bit mute..............30 million tons of water travelling at 140 km...........does a lot damage.........

That wiki scares the bejesus out of a man ........... Mr Dow ..... I'm reading your thread with interest :o

[ianoz]

Just out of interest Peter , ,What engineering degrees do you have ? And how much practical experience do you have under your belt .
Have you actually been to the site to study the site first hand .

[Peter Dow]

Just out of interest Peter , ,What engineering degrees do you have ?

None. I'm not a professional engineer. I'm more of a scientist than an engineer. I have a Computer Science degree with some mathematics and physics in my educational background as well.

And how much practical experience do you have under your belt.

Of what? This is my first plan for a pumped storage hydro-dam scheme if that is what you mean. My only job after university was as a Computing & Mathematics lecturer at a college but that finished in 1986. Essentially I have been on welfare since then but keeping myself busy with one thing and another.

I didn't come here to discuss my life and work history. I don't invite comments about that. You asked a civil question so I am giving a civil answer. To be honest, I would rather we just kept to the topic in hand and never mind personal discussions or comments about me.

I don't come to this forum presenting a visionary plan and saying "My plan is right because some university or some professional body has given me accreditation so never mind looking at the details, don't question my plan, just trust me".

On the contrary, if there are any professional engineers or those with a lot of experience in construction here who look at my plan and can point out flaws in it, I would be delighted to read detailed criticism.

I do value people who know their stuff and who have knowledge to pass on. I welcome those types of replies.

What I won't be impressed with is a professional engineer who doesn't have anything more to say about my plan other than "I am a professional engineer and you are not and your plan is rubbish because I say so, nah, nah, na, nah nah!"

Either my ideas are of interest to somebody, on their own merits and they want to discuss them, or my ideas are of no interest and they don't want to discuss them. Either way it is fine my me.

Have you actually been to the site to study the site first hand .

No but I have had pretty good look around using google maps, earth & street view.

[Peter Dow]

Geological survey information for the Coire Glas site

I don't seem to have posted the geological survey information I used in this earlier post I am quoting to identify the bedrock as "psammite". So I will now provide that, after the quote.

Dam foundations and height of the dam above the bedrock
The top of the Dow-Dam has an elevation of 780 metres by design.




Image also hosted here

The lowest elevation of the current ground surface of Coire Glas along the line of the proposed dam is 463 metres and subtracting 463 from 780 is how the initial value of 317 metres for the nominal height of the dam above the existing surface used in previous diagrams was arrived at.

However, the glacial deposit of as yet unknown thickness is to be removed before building the foundations of the dam within and upon the bedrock.

Although the lowest surface elevation along the line of the dam of the bedrock too is unknown a formula relating the Height of the Dam Above the Bedrock (HDAB) to the Glacial Deposit Depth (GDD) can be easily stated.

HDAB = 317 + GDD

Examples.

If the GDD turns out to be 13 metres then the dam will be 330 metres tall.
If the GDD turns out ot be 83 metres then the dam will be 400 metres tall.




Image also hosted here

I propose that the height of the Dow-Dam be as tall above the bedrock as it needs to be to keep the top of the dam at an elevation of 780 metres no matter how deep the removed glacial deposit layer turns out to be.

My approach may well differ from the SSE's approach. The SSE have said that their dam will be "92 metres" high and they may stick to that without having any goal for the elevation of the top of their dam.

As the diagram indicates, I propose to secure the Dow-Dam to the bedrock by massive piles inserted and secured into shafts which would be drilled into the bedrock.

Geology of the Coire Glas site

I have been able to extract this information from the British Geological Survey (BGS) Geology of Britain viewer, from the 1:50 000 scale map.




Click to see larger image

According to this map, the bedrock at the site which would be used to build the dam on top of and to extract rock from to create the tunnels for the underground complex seems to be a rock geologists call "psammite" which I understand to mean here "a metamorphic rock whose protolith was a sandstone".

What neither the map nor the "psammite" name is telling us is how fractured the psammite rock there is and therefore how strong and also how impermeable or otherwise to water this rock is likely to prove to be, both of which would be interesting for any engineers building a pumped-storage hydro dam scheme there to know.

What does look fairly obvious to me is that the superficial deposit of what the map calls "hummocky (moundy) glacial deposits - diamicton, sand and gravel" would not be strong enough, nor impermeable enough to build any dam on top of and at least along the line of the dam, this glacial deposit ought to be removed to get down to the bedrock within which to establish the foundations of the dam, although I would think that this glacial deposit might be made into aggregate to make the concrete for the dam by the sounds of it.

[ianoz]

As you well know Peter , You have posted this on Many other forums ,. I have read a lot of the replies you have recieved , Most questioning a lot of the ideas you put forward ... I read you say on the Phisics Forum I beleive That you miscalulated the Area of capasity needed in Loch Lochie By 25% . In your diagram of Loch Lochie It appears that is a Big problem .When the Coire Glas reservoir is full, then the water level of Loch Lochy should be prevented, by new water works - drains, dams, flood barriers etc. - from rising due to rainfall and natural flow into the loch above a safe level which allows for the reservoir to empty into the loch without overflowing and flooding.

The safe "upper-reservoir-full" loch level will likely turn out to be around about 15 metres below the maximum loch level.

The next diagram showing the new loch drain and the reservoir pump inlets indicates how this might be achieved.




lem As there does not appear to be the freeboard required .

[Peter Dow]

As you well know Peter , You have posted this on Many other forums ,. I have read a lot of the replies you have recieved , Most questioning a lot of the ideas you put forward ... I read you say on the Phisics Forum I beleive That you miscalulated the Area of capasity needed in Loch Lochie By 25% . In your diagram of Loch Lochie It appears that is a Big problem .

lem As there does not appear to be the freeboard required .

I am not following you very well ianoz. You are not helping to make your point by not properly marking out what is a quote of my post and what is your post.

I suggest you stick to what I have posted in this forum. If you can point to a miscalculation appearing anywhere here I would be happy to have a look.

When the Coire Glas reservoir is full, then the water level of Loch Lochy should be prevented, by new water works - drains, dams, flood barriers etc. - from rising due to rainfall and natural flow into the loch above a safe level which allows for the reservoir to empty into the loch without overflowing and flooding.

The safe "upper-reservoir-full" loch level will likely turn out to be around about 15 metres below the maximum loch level.

The next diagram showing the new loch drain and the reservoir pump inlets indicates how this might be achieved.

Now, what seems to be the problem exactly? Can you be more specific?

[ianoz]

Yeah I stuffed up ,with the post . I should have quoted your part of it . I had a reasonable space between what i wrote and what i had pasted, but the forum removed the space . I just Googled Loch Lochie And found this You tube video . It is of a motor bike traveling beside the loch .. There appears to be a reasonable amount of traffic on the road and a number of houses .If you increase the height of the loch All of this will be underwater . Does you plan Allow to compensate the owners of these flooded propertys . And Buld a new road ? Video Link
http://www.youtube.com/watch?v=I-UZX4JxVyI
I will go and see if i can find the piece you wrote .

[Peter Dow]

Yeah I stuffed up ,with the post . I should have quoted your part of it . I had a reasonable space between what i wrote and what i had pasted, but the forum removed the space . I just Googled Loch Lochie And found this You tube video . It is of a motor bike traveling beside the loch .. There appears to be a reasonable amount of traffic on the road and a number of houses .

Google streetview is best for having a roadside view around there.

If you increase the height of the loch

I'm not.

The natural surface elevation or "height" of Loch Lochy now is 29 metres above sea level. 29 metres would be the maximum operational level in my scheme.

I do propose to permanently lower the surface elevation of Loch Arkaig, to bring that down from its current 43 metres to the very same 29 metres that Loch Lochy is now at, by joining the two lochs with a wide and deep water channel.

The surface elevations would at times go down to a surface elevation of 14 metres above sea level or perhaps a little lower.

In operation, the volume of water in the upper reservoir up Coire Glas (when full) has enough water to add about 15 metres in depth to the new combined Loch Lochy & Loch Arkaig system (when the water flows down from the upper reservoir into the lower lochs).

So 14 + 15 = 29 and so the water level in Loch Lochy won't ever be any higher than it is now.

All of this will be underwater . Does you plan Allow to compensate the owners of these flooded propertys . And Buld a new road ? Video Link
http://www.youtube.com/watch?v=I-UZX4JxVyI
I will go and see if i can find the piece you wrote .

So no. None of that would be under water.