World’s biggest-ever pumped-storage hydro-scheme, for Scotland?


Design for the biggest-ever pumped-storage hydro-scheme.
Design for the biggest-ever pumped-storage hydro-scheme.

Click for a larger image

The map shows how and where the biggest-ever pumped-storage hydro-scheme could be built – Strathdearn in the Scottish Highlands.

Energy storage capacity

The scheme requires a massive dam about 300 metres high and 2,000 metres long to impound about 4.4 billion metres-cubed of water in the upper glen of the River Findhorn. The surface elevation of the reservoir so impounded would be as much as 650 metres when full and the surface area would be as much as 40 square-kilometres.

The maximum potential energy which could be stored by such a scheme is colossal – about 6800 Gigawatt-hours – or 283 Gigawatt-days – enough capacity to balance and back-up the intermittent renewable energy generators such as wind and solar power now in use for the whole of Europe!

1000km 2000km & 3000km from StrathdearnTransmission losses

Most of Europe is within 3,000 km of Strathdearn meaning that one-way transmission losses to or from anywhere in Europe could be as low as 10.5% using existing high-voltage (800 kV), direct current (HVDC) electric power transmission system.

In theory, transmission power losses are inversely proportional to the voltage-squared so it is possible that if and when even higher voltage than 800 kV transmission technology were to be developed, transmission losses could be reduced still further.

Transmitting power at 800 kV to and from a well-designed efficient pumped-storage hydro-scheme, two-way transmission losses are

  • at distances of 2000 km to 3000 km, from 14% to 21% and represent the single most significant loss factor, indicating that 800 kV is an inappropriately low transmission voltage for service at this distance – 800 kV at this distance is not recommended but possible meantime if and while no better option is available
  • at distances of 1000 km to 2000 km, from 7% to 14% and so the losses at the pumped-storage hydro scheme itself are likely to be the single most significant loss factor – 800 kV at this distance is not ideal, may be practical but reconsider if and when there are any better options
  • at distances of less than 1000 km, less than 7% and so losses are acceptable – 800 kV at this distance is ideal and recommended for full service life for Scotland, England, Wales, Ireland, southern Norway, Denmark, north-west Germany, Netherlands, Belgium and northern France.


There would need to be two pumping and turbine generating stations at different locations – one by the sea at Inverness which pumps sea-water uphill via pressurised pipes to 300 metres of elevation to a water well head which feeds an unpressurised canal in which water flows to and from the other pumping and turbine generating station at the base of the dam which pumps water up into the reservoir impounded by the dam.


To fill or empty the reservoir in a day would require a flow rate of 51,000 metres-cubed per second, the equivalent of the discharge flow from the Congo River, only surpassed by the Amazon!

The power capacity emptying at such a flow rate could be equally colossal. When nearly empty and powering only the lower turbines by the sea, then about 132 GW could be produced. When nearly full and the upper turbines at the base of the dam fully powered too then about 264 GW could be produced.

Modelling of a wind turbine power and pumped-storage hydro system recommends –

  • store energy capacity = 1.5 days x peak demand power

suggesting that a store energy capacity of  283 GW-days would be sufficient to serve a peak demand power of 283 / 1.5 =  189 GW, though this could only be produced from reservoir heads of at least 430 metres, at least 8% of energy capacity, assuming a flow rate of 51,000 m3/s. To supply 189 GW from the lowest operational head of 300 metres would require increasing the flow capacity to 73,000 m3/s.

This represents many times more power and energy-storage capacity than is needed to serve all of Britain’s electrical grid storage needs for backing-up and balancing intermittent renewable-energy electricity generators, such as wind turbines and solar photo-voltaic arrays for the foreseeable future, opening up the possibility to provide grid energy storage services to Europe as well.


The empirical Manning formula relates the properties, such as volume rate, gradient, velocity and depth of a one-directional steady-state water flow in a canal.

Application of Manning Formula To Power Canal Design

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For 2-way flow, the canal must support the gradient in both directions and contain the stationary water at a height to allow for efficient starting and stopping of the flow.

2-way Power Canal

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The “2-way Power Canal” diagram charts from a spreadsheet model for a 51,000 m3/s flow how the width of the water surface in a 45-degree V-shaped canal varies with the designed maximum flow velocity. The lines graphed are

  • Moving width – from simple geometry, for a constant volume flow, the faster the flow velocity, the narrower the water surface width
  • Static width – the width of the surface of the stationary water with enough height and gravitational potential energy to convert to the kinetic energy of the flow velocity
  • 30km 2-way wider by – using the Manning formula, the hydraulic slope can be calculated and therefore how much higher and deeper the water must begin at one end of a 30km long canal to have sufficient depth at the end of the canal and therefore by how much wider the canal must be
  • Canal width – adding the 30km-2-way-wider-by value to the static-width determines the maximum design width of the water surface.

The equation thus derived,

y = 2 √ ( 51000/x) + 0.1529 x2 + x8/3/40

where y is the maximum surface water width in the canal and x is the designed maximum flow velocity

predicts a minimum value for the canal width of about 170 metres (plus whatever additional above the waterline freeboard width is added to complete the design of the canal), containing up to 216 million cubic-metres of water, at a design maximum flow velocity between 10 and 11 metres per second, similar to the velocity of the 2-way flow of the fastest tidal race in the world at Saltstraumen, Norway.

Video of the tidal race at Saltstraumen

Guinness World Records states that the widest canal in the world is the Cape Cod Canal which is “only” 165 metres wide.

Strathdearn Power Canal width compared to Cape Cod Canal

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The construction of the Panama Canal required the excavation of a total of 205 million cubic-metres of material but the Strathdearn Power Canal would need more excavating and construction work than Panama did.

The Panama Canal

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So the Strathdearn Power Canal, too, would be the biggest ever!

Canal efficiency

To improve the power canal’s energy efficiency requires designing for a slower maximum flow velocity which requires a wider moving and static width of the water surface to maintain the maximum volume flow rate which –

  • increases the canal’s construction costs
  • decreases the canal flow’s hydraulic slope
  • decreases the canal’s 2-way hydraulic head height loss, at most equal to the 30km-2-way-wider-by
  • decreases the canal’s energy loss
  • increases the canal’s energy efficiency

So a wider canal would be more expensive to build but would be more energy efficient in use, saving energy costs over the longer term. A wider canal also allows for a higher flow rate. For example, 62,000 m3/s – which could be useful to power 159 GW when the reservoir was running low, assuming additional turbines were installed for such a purpose – would require a minimum canal width of 182 metres.

For a minimum canal width of 170 metres and a flow rate of 51,000 m3/s, implying a maximum flow velocity of 9.8 m/s, the 30km-2-way-wider-by  is 11 metres so the maximum 2-way hydraulic head height loss as a proportion of the reservoir operational head heights from 300 to 625 metres would represent an energy loss from 11/625 = 1.8% to 11/300 = 3.7%, averaging presumably somewhere around 11/462 = 2.4%, estimating the power canal to be about 97.6% efficient when operated at full power and even more efficient at reduced power. The follow table indicates how energy efficiency increases with canal width.

Table of canal efficiency for a flow rate of 51,000 m3/s

Width (m) 2-way head loss (m) Energy loss Efficiency
170 11.1 2.4% 97.6%
180 5.1 1.1% 98.9%
190 3.3 0.72% 99.3%
200 2.3 0.51% 99.5%
210 1.7 0.37% 99.6%
220 1.3 0.28% 99.7%
230 1.0 0.22% 99.8%

Canal lining and boulder trap

Boulder Trap for Power Canal

To maximise the water flow velocity, canals are lined to slow erosion. Concrete is one lining material often used to allow for the highest water flow velocities, though engineering guidelines commonly recommend designing for significantly slower maximum flow velocities than 10 m/s, even with concrete lining.

Water flowing at 10 m/s has the power to drag large – in excess of 10 tonnes – boulders along the bottom of a canal with the potential of eroding even concrete, so I suggest that the bottom 6 metres width of the lining, (3 m either side of the corner of the V) may be specially armoured with an even tougher lining material than concrete and/or include bottom transverse barriers of 2 metres depth to impede the flow along the corner of the V and trap boulders, smaller stones and gravel, in which case the water flow is more precisely modelled for Manning formula calculations as a trapezoidal canal with a bed width equal to the 4 metre width of the top of bottom transverse barrier (“boulder trap”) and a 2-metre smaller depth from the top of the boulder trap to the water surface.

Main Dam

Strathdearn Dam

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The image shows the location of the main dam at latitude 57°15’16.2″N, decimal 57.254501°, longitude 4°05’25.8″W, decimal -4.090506°.

Assuming the dam would be twice as wide as its height below the dam top elevation of 650 metres, the superficial volume is estimated at 80 million cubic metres, not including the subterranean dam foundations which would be built on the bedrock after clearing away the fluvial sediment.



Click to view a larger image

The image shows an extract from the British Geological Survey’s bedrock map overlaid upon my plan for the Strathdearn Pumped-storage hydro scheme. Readers are referred to the BGS’s Geology of Britain viewer for details.



60 thoughts on “World’s biggest-ever pumped-storage hydro-scheme, for Scotland?”

  1. When the facility is generating, will there be problems maintaining the required flow along the canal to maintain the head in the Inverness pipe/generator? Assuming the goal would be to be able to generate a few GW, I wonder if the design would need to include a quite-large holding pool at the Inverness end of the canal?


    1. David,

      I’m honoured to welcome your first comment on my blog – the first of many I hope. Your book – “Sustainable Energy – without the hot air” by David JC MacKay is the 2nd-most quoted reference source (after Wikipedia) in the online discussions I have been party to regarding renewable energy, especially your Chapter 26 “Fluctuations and storage” in the context of pumped-storage hydro.

      I rushed this post out in the early hours of this morning because I am keen to share my design concept at the earliest opportunity regardless that many key details of my proposal remain unspecified in the post at this time (15 April 2015). I intend to update this post on my own initiative and in answer to comments such as yours.

      The most important missing detail in the first draft of this post is (was) any estimate for the power capacity. Whilst we may agree that power capacity should be in proportion to the energy storage capacity, we may differ on precisely what constant of proportionality to recommend.

      On page 189 of your book, you recommend storage capacity equivalent to 5 days of average power. Attempting to follow the guidance in your book, from an energy storage capacity of 100 GW-days, would not your book’s recommendation for power capacity be the peak power equivalent of 20 GW average power (1.6 x 20 = 32 GW peak power) or for 200 GW-days energy storage then the peak power equivalent of 40 GW average power (1.6 x 40 GW = 64 GW peak power), which is a lot more than “a few GW”?

      Peak-power is the more relevant nameplate specification for a pumped-storage hydro-scheme because pumps and turbines must be able to handle peak power, not only average power.

      In my blog post “Modelling of wind and pumped-storage power” I modelled a smaller constant of proportionality for energy storage capacity of only 1.11 peak-demand-days (equivalent to 1.6 x 1.11 = 1.77 average power-days), with satisfactory results. So, as of now, I’m recommending only “1.77 days” equivalently compared to your “5 days”, a constant of proportionality of about a third of yours.

      Accordingly, I’d recommend for 100 GW-days, a nameplate peak power capacity of 100 / 1.11 = 90 GW, and for 200 GW-days, 180 GW. As you can see this is considerably in excess of UK peak demand of 60 GW, opening up the possibility to provide grid energy storage services to Europe as well.

      Those figures had to be discussed first before turning to the requirements for water flow through the pumps, the pipe and the canal because all of the features of the hydro scheme must be scaled appropriately.

      The required flow rate of water can be calculated, as you know, from the head and the power capacity and the empirical Manning formula may be used to design the cross-sectional area of a canal to achieve the required flow rate.

      So to get to your question David, yes there would indeed be problems in maintaining the required flow along the canal to maintain the head – at both ends because flow is in both directions – but a holding pool at either end, however large, would not solve those problems. Only a canal of a sufficient cross section with additional design features as required could hope to do so.

      I’ve not done any estimates for the required minimum cross section of the canal as yet but that’s of interest certainly.

      Once again, David, I must tell you how ‘fair chuffed’ I am that you commented on my post!

      Liked by 1 person

      1. As it’s only 16 metres above sea level, I’d say it would be highly desirable to use Loch Ness as the lower reservoir, so that the entire system is fresh water.

        I agree with David Mackay, continuous pipes or tunnels bored through the mountain would seem to be the best option to connect upper and lower lochs. To my knowledge, all existing PHS uses that design principle. Is the flow capacity an issue here?
        The main problem I see, aside from the undoubtedly high cost and objections to flooding a valley, would be the massive transmission capacity required to make this scheme work. The proposed NorthConnect cable is costed at £1.7bn for 1.4GW. I must say, the idea of selling Scottish wind power to Norway and buying it back at a higher price strikes me as ridiculous.


        1. Hi Dave and thanks for your comment.

          Such is the volume of water in the reservoir were it to be emptied into Loch Ness, it would massively flood Loch Ness and flood the surrounding land.

          Likewise, filling the reservoir up from Loch Ness would drain Loch Ness and soon leave the pumps running out of water to draw in. The problem arises because the volume of the reservoir would be comparable to the volume of Loch Ness. For such a large reservoir, the Scottish lochs are simply too small to serve as the lower reservoir.

          I think my canal concept may be somewhat new in the context of pumped-storage hydro schemes, yes.

          Flow capacity is indeed an issue with attempting to go very far underground because of the size and number of tunnels required. As you can read in the updates to the post, the canal I have designed to carry the full flow would be the biggest-ever.

          I’ve not filled in the details for the “pipe” indicated in the map but I think I may be straying into “biggest-ever” territory again. Going underground may not the best solution here. Perhaps extending the canal concept to go over the surface to the sea, including a number of smaller hydro-schemes steps on the way, may be the way to go?

          The required transmission capacity would be massive too, admittedly.

          Pumped-storage schemes buy power when it is cheap – when the wind is blowing a gale or the sun is blazing – and sell it when it is more expensive, when it is calm or dark, not the ridiculous other way around.

          Norway is very well served with pumped-storage, as is Sweden (Edit: Swedish hydro-schemes which could be upgraded to PSH operation), so the market for European grid energy storage services is likely to come from elsewhere in Europe.


  2. Thanks for your response. I think that working out the rough intended flow rate and required cross-section is a priority. My guess (without having done the Manning calculation either!) is that your canal’s cross-section (in the current design) would have to be unrealistically large; but if you redesigned to include holding ponds (sized to be able to serve up say 6 hours of water without significant loss of head) then maybe you could get by with a more realistic canal. Let me know when you’ve done the Manning thing!

    My instinct is that this issue I’m raising is critical, and it might be best to focus on locations where a continuous pipe can be bored or laid all the way from top loch to the bottom. I think there are lots more places in the Highlands where mega-reservoirs could be created.


    1. David,

      I’ve updated my post to include more detailed estimates for the reservoir volume, maximum flow rate, energy storage and power capacity.

      I’ve also used the Manning formula to estimate a canal size to cope with the maximum flow rate and as with seemingly everything else in this design, the canal too is “unrealistically” large.

      I think your “holding ponds” idea and smaller canal would turn my well-thought-out design into a cobbled-together system performing essentially not unlike two normally-powered separate pumped-storage schemes – the lower sea-side scheme limited by its smaller holding pond for an upper reservoir and the upper dam-side scheme limited by – presumably – its own holding pond near the base of the dam functioning as the pump-at-the-base-of-the-dam’s lower reservoir?

      The sizes of both holding ponds would severely limit the power and energy capacity performance of the scheme as a whole and defeat the whole purpose of a design incorporating such a big reservoir. So no David, I don’t support your holding ponds idea but will stand by my concept for a canal to carry the full flow of the scheme at full power.

      As I think we’d agree, the location of the upper reservoir is just too far from the sea to go underground all the way but my opinion is that it is such an exceptional site for a such a big reservoir that I think it is worth figuring out a design to get maximum power from it and the biggest-ever canal is my solution.

      I’m not stuck for design ideas but I do appreciate your interest, David. Thank you very much.


    1. David, I have come across another proposal for a pumped-storage hydro-scheme which uses much the same location as you have identified in your comment.

      Energy Storage Solution for the UK: Large Scale Pumped-Storage Site – by Julian Hunt – published on The Energy Collective – the world’s best thinkers on energy and climate.

      I can see from your book that you had scoped Loch Morar out as one of your 13 potential sites for pumped-storage.

      Figure 26.10. Lochs in Scotland with potential for pumped storage.
      Figure 26.10. Lochs in Scotland with potential for pumped storage – from Sustainable Energy – Without The Hot Air – by David MacKay.

      Did you have in mind, as Julian Hunt does, using Loch Morar, immediately to the north, as the lower reservoir?

      The upper reservoir which is only identified on Google maps with the text Allt a’ Choire is named on another map as Loch Beoraid.

      Julian Hunt suggests using Loch Morar sufficiently drained so that its lowest level in use would be minus 300 metres below sea level.

      Were you of a mind to use Loch Morar without prior draining it so low?

      Julian Hunt reckons he can get 1300GWh energy storage capacity with a 300 metre dam and 1800GWh with a 350 metre dam.

      My own modelling indicates that a capacity of 1,400 GWh would be appropriate to serve all of the UK’s needs for energy storage for an essentially renewables-only generation capacity to serve all of the UK’s electricity demand, without nuclear or fossil fuel power stations, except perhaps mothballed for emergency power.

      So a claim of “1,300 GWh” is of interest. As is Julian’s further claim of “1,800 GWh” with a higher dam.

      I can identify some issues and questions now with Julian’s proposal which are mainly to do with the lower reservoir.

      1) The surface area of the lower reservoir when drained to a depth of -300 metres and therefore the volume which can be lowered to that depth is likely to be small.

      It would be nice to read some of Julian’s thinking as to what assumptions he made to get to the 1,300 GWh or 1,800 GWh figure.

      2) There would be a greater difficulty in sealing the lower reservoir from ingress from sea water from factures in the bedrock.

      Sealing water in to an upper reservoir is not too hard because the water pressure forces the sealant further into the fractures.

      But in the lower reservoir, any sea water ingress will be forcing any sealant to pop out of the fractures which makes sealing much more difficult.

      This is not an insurmountable problem for tunnels which go under seas or rivers and mining operations below sea level but is a lot easier if the bedrock is impermeable to start with – otherwise pumping out continuously may be the obvious solution but that takes energy, not an issue unless that energy is too high, which it could be in this case but I don’t know.

      I wonder if Julian has worked out a figure for the energy it would take to drain the lower reservoir of the water to the sea which could not be contained in the upper reservoir? The operators would not want to be wasting energy bailing the lower reservoir out of sea water too often.


  3. Physics, and even civil engineering, is a lot easier than economics and politics.

    What would be the capital cost, delivery time, and return on capital of this project?

    The present instability of the United Kingdom militates against any major new central investment north of the border (some of us remember the nationalisation of the Suez Canal) so the project must either be funded from taxes raised in Scotland or entirely from private venture capital. It would be difficult to sell a project to the Scottish Parliament where the intended principal beneficiaries would be in England (Scotland probably doesn’t need this project at all, and certainly not on this scale), and difficult to pitch for private capital if there is no chance of a 20% per annum return witin 5 years.

    Since the project only generates revenue when (a) the grid is heavily dependent on unreliable sources of power (b) there is sufficient overcapacity of free power to recharge the reservoir whilst meeting current demand and (c) those sources have failed, how do we avoid a chicken and egg situation? Existing pumped storage systems of any significant size have been built as part of a planned and integrated generating and transmission system but the modern political trend is towards relatively small, private, opportunistic generators and there is almost no recent history of significant grid-sourced storage.

    Longterm, say over the next 50 years, wind power and some form of storage makes a lot of sense, but neither governments nor modern capitalists tend to think beyond the next general election.


    1. Hi Alan and welcome to my blog after we replied to each other in the “How can renewable energy farms provide 24-hour power?” topic in the University of Cambridge’s “The Naked Scientists” forum, where you made a similar point.

      "Scale is important because this project requires capital input. There is obviously no physical reason why it can't be done but the practicality is that you need enough money up front to start the work, with a sufficient promise that it will be funded to completion. Failing that, a project will run into the sand as lack of continuing funding means delay, which increases costs and makes further funding less attractive.

      Whilst Scottish independence remains a serious possibility, it won't be funded by the UK government, so the money has to be raised either by private investors or by taxing the Scots for long enough to build up the required capital reserve (and not spending it on something else, which politicians are bound to do)."

      Scottish Scientist
      “I think the way to build this is not all at once but first to build part of the sea-side scheme, using a length of canal as an upper reservoir.

      Get a system working for Scottish 2020 renewables-only needs then once the team which has done that has a working scheme in place, hopefully the investment to complete the rest of the sea-side scheme and the reservoir and dam-base pumps would become available.

      That way at least we’d have working pumped-storage to show for any investment if the money ran out before final completion.”

      "So, let's have some cost estimates, please!"

      Scottish Scientist
      “8 GW / 8.5 GW-days – £5.4 billion (Scottish needs demonstrator project, using about 20km of canal as the upper reservoir)
      264 GW / 280 GW-days- £180 billion.”

      As for delivery time, that depends on how quickly the money is spent.

      Government deficit spending could finance the entire project so private capital would not be necessary but could be attracted by a government-guaranteed return on any private capital invested.

      I take inspiration from the many collaborative international projects – the international space station, CERN – the European Organisation for Nuclear Research, the Channel Tunnel, Concorde, Airbus etc.

      Politically independent countries and the devolved countries within them do find a way to give permission to, to fund, to build and to run mutually advantageous projects which span international borders, government term limits and bank loan repayment dates.

      Where there is an international will, there is an international way.

      I think the people of many countries do appreciate the efforts of scientists and engineers to innovate with a view to providing clean renewable energy which protects the environment.

      That’s why I have presented this plan and why I think it may be considered respectfully and be given a fair wind, by Scots, by Britons and by Europeans and in due course by their elected representatives and governments. This would be a project which would need government backing and indeed bankrolling to proceed to construction.

      You are one of those who has remembered Suez Alan but are you also one of those who has learned nothing from it?

      If I may digress to teach as a social scientist, the UK remembers its history with pomp, circumstance and flummery but is ignorant when it comes to learning the appropriate lessons from the events it remembers so well.

      The lesson to learn from Suez is that the UK’s error has been sometimes to pursue the opposite approach to international collaboration.

      Rather the UK has sometimes resorted to the dangerous approach of imperialism, overriding national sovereignty by brute force
      – overriding Egypt’s national sovereignty in the crisis over the Suez Canal
      – overriding Britain’s national sovereignty and the sovereignty of the home nations as our soldiers were dragged ineptly into the imperialist conflict over the Suez canal.

      The UK is, by definition, a kingdom and therefore a bastard state, a creature of the monarch and not a nation state democratically accountable to the people.

      So the UK is institutionally unwilling to educate the people about the difference between the nation and the state because to do so would lead the people to question the legitimacy of the UK’s own existence.

      Here is the difference between the “nation” and the “state” for you to learn Alan.

      The state does what PM Cameron or FM Sturgeon decides or what the UK’s judges or other officials decide.

      The nation supports what the nation’s people freely support – “freely” meaning not only on election day, not by brainwashing the people via state control of broadcasting and not by arresting those who vociferously dissent.

      The successful projects are those which win the support of all of the collaborating nations, all of the people who are involved.

      The unsuccessful imperialist ventures are those which are imposed by the state or states against the will of the people and the nations.


      1. You most certainly hit the nail on the head about the way our nation operates. I am not a professional in this industry, but I did build the largest autonomous building in the UK… Powered by wind, hydro and solar all working with each other intelligently.
        I think Scotland needs a bold vision to take us forward in the fight to become totally renewable.
        The dreamers should dream big, and capture the nations hearts, so public opinion eventually demands we take this further.
        I sincerely wish you well with this bold concept brother.
        And maybe an independent Scotland would ambitiously draw on private enterprises to engage with us on such a grand plan.
        It pisses me off that on the one hand, we have to chip in for HS2, yet it’s openly discussed how the South will never back a major Scottish enterprise like this in case we go it alone at some point.
        GOOD LUCK!!! 🙂

        Liked by 1 person

        1. Fran,
          If I’ve hit the nail on the head this time it is only after practice, mishits and injuries.
          What’s the name of your “largest autonomous building in the UK”? I’m curious to search to see what information there might be on the internet about it.
          My Strathdearn pumped-storage hydro-scheme plan is so big that it far exceeds the requirements for energy storage capacity required to make Scotland’s energy totally renewable and it exceeds by about 5 times the requirements for energy storage capacity required to make Britain’s electricity totally renewable. Britain may in future eventually electrify much more of its transport and heat energy usage but not until this future eventuality could Britain conceivably need all of this energy storage capacity.
          So that’s the practical reasons why I’d like to engage with European energy experts to propose this scheme to serve our European neighbours’ needs for energy storage as well.
          Every such scheme would require the permission and licence from the Scottish government so persuading Scottish energy experts and winning the support of Scottish public opinion would be an essential step along the way.
          On a personal emotional level, capturing the hearts of the Scots for any vision of mine would be a dream come true for this patriotic Scot and so I’m moved to song by your generous comment Fran. Thank you.

          Towering in gallant fame,
          Scotland my mountain hame,
          High may your proud
          standards gloriously wave,
          Land of my high endeavour,
          Land of the shining river,
          Land of my heart for ever,
          Scotland the brave.

          Scotland the Brave – YouTube


  4. I am familiar with pumped storage because I have a mountain cabin in Clear Creek Colorado USA which is the home for the Cabin Creek PHES plant. It takes the resources of a large number of engineers, scientists and even economists to determine if it is even feasible to develop any a large scale PHES and here you are taking about GW of power and GWh of energy. As you know, funding for even the primary development work is hard to get unless you are associated with a university, NGO or government agency (at least in the USA). Have you tried crowd funding? You are talking about pounds (dollars) in the high six figures just to start.

    I have tried to use KICKSTARTER just to fund my travel expenses to give a paper in Rome titled “The Levelized Cost (US$/MWh; €/MWh) of Storing PV (Wind) Electricity (LCOSE) at a Grid-Connected Utility-Scaled (MW) Energy Storage System (ESS)”. Check my project and its funding progress on


    1. Let me reply to my own comment. My paper’s levelized cost of storing energy (LCOSE) algorithm is energy storage system (ESS) technology agnostic (pumped storage, flywheel, capacitor, CAES, hydrogen, PV (wind) “battery” [Pb-a, NaS, NiMH, Li-Ion, etc.], etc.). The nine required ESS LCOSE specifications are ESS power-MW; ESS electric storage capacity-MWh/day; ESS Plant CapEx-[ US$/plant; €/MWh],ESS efficiency-η; cost of the electricity to be stored-COE-US$/MWh (; fixed and variable O & M expense; physical life-yr; cost of capital-%.


      1. Let me tidy up my spec list: The nine required ESS LCOSE specifications are: 1. ESS power-MW; 2. ESS electric storage capacity-MWh/day; 3. ESS Plant CapEx-[US$/plant; €/MWh], 4. round trip ESS efficiency-η; 5. cost of the electricity to be stored-COE-[US$/plant; €/MWh]; 6. fixed and 7. variable O & M expense; 8. physical life-yr; 9. cost of capital-%.


    2. The internet allows for scientists and engineers cheaply and efficiently to consider the feasibility, pros and cons of suggested projects such as this one, by-passing previous progress-bottlenecks of having to get employed to research something, get your proposals published in journals, present papers at meetings etc.

      I’ve ALREADY STARTED so sit up and take notice of this blog all those in their ivory towers!


  5. I would reduce the scale, make it 100 % fresh water, and use three dams to set up three reservoirs. The head would be reduced, but it sure looks more practical. What are the rocks like? Granite? Are they fractured?


    1. I’ve edited my post to add an image showing an overlay of the British Geological Survey’s bedrock map to my site map. I’d invite you to research the rock types if you are interested and let us know your findings.


  6. The design assumes a symmetrical flow along the canal. If the aim is to provide pump storage for longer supply / demand variations than the daily cycle that most PS schemes cater for then you probably only need to recharge at 10 – 20% of capacity. That means your canal can have a gradient, and therefore be much smaller. As long as the top of the lower reach of the canal is still say 20m above the bottom of the upper reach of the canal then the slower recharge flow rates would be achieved.
    The reality of trying to build such a wide canal on such steep terrain is probably the biggest engineering challenge, just following the contours will require huge cuttings and embankments on the respective uphill and downhill sides. The scheme might be more viable with several shorter steps, each with a head of say 70-100m; shorter canals would mean smaller cross sections needed.
    For my money, if I had the odd billion to invest, I would start with a smaller scale scheme on the site, with a smaller dam engineered to allow for future expansion. A less risky investment proposition, with the built in future option to grow if the finances stack up.


  7. The aim is to provide for shorter, not only “longer” supply / demand variations so recharging power must be possible at 100% of discharging power.

    Most of the canal follows the course of rivers, within wide river valleys / glens, so I’m not sure why you say “such steep terrain”?

    I have already suggested in an earlier comment beginning with a smaller scheme.

    “I think the way to build this is not all at once but first to build part of the sea-side scheme, using a length of canal as an upper reservoir.

    Get a system working for Scottish 2020 renewables-only needs then once the team which has done that has a working scheme in place, hopefully the investment to complete the rest of the sea-side scheme and the reservoir and dam-base pumps would become available.

    That way at least we’d have working pumped-storage to show for any investment if the money ran out before final completion.

    8 GW / 8.5 GW-days – £5.4 billion (Scottish needs demonstrator project, using about 20km of canal as the upper reservoir)”


  8. It is a lovely idea, but there are several huge obstacles that I can envisage.

    1./ Efficiency.
    PS systems are at best c. 85% efficient and there is no reason to think this large system would be above that – indeed for various reasons it would probably be lower.
    Transmission – we do not have the technology to transmit such huge amounts of power over such large distances other than by HVDV – nothing big enough and vastly expensive.
    No country has the grid capacity to do this so all the participants would have to upgrade.
    Even if all power in/out interlinks were in the right place/s the losses would be huge as well.
    3./ Timing –
    When it is dark in the UK it is dark over Europe plus tides and winds are interrelated as well.
    In other words we would be storing and discharging at the same time – you would not need two sites you would need many.
    Surplus power.
    To fill(charge) the reservoir from ‘spare’ renewable capacity to run our systems 24/7 we would need a massive over capacity.
    We are not even close and with existing coal and nuclear plants closing and a moratorium on low carbon footprint fracked gas, we are at least a generation away from that.
    Chicken and egg – Not only do we not have even close to capacity, we cannot utilise more than a certain amount of renewables without storage.
    We would have to build a staggeringly huge renewables infrastructure and not use it until the reservoir was completed, plus it would take about a year to fill at full power from all Europe’s spare capacity…. that it does not have.

    You’d be far better off building a few new nuclear plants.

    They’re half the cost of off shore wind, don’t need ANY storage or interlinks to run and the latest molten salt reactors can recycle our old nuclear waste, turning it into low grade waste and the electricity is affordable to the consumer, thus avoiding fuel poverty.

    Only the Luddites stand between us and Zero carbon energy from recycled nuclear fuel -enough to power the Uk for c. 500yrs.

    No hazard to costly shipping from windmills, no costly interlinks or grid restructuring or fleets of support vessels and not a single drowned sheep.


    1. Thank you for your comments Nikki.

      1. Efficiency. The canal is a unique feature of this design which introduces a potential inefficiency so I’ve edited my post to add a section titled “Canal Efficiency” which explains how, by widening the canal and slowing the flow, energy losses be minimised to the point of being negligible.

      2. Transmission. I’ve edited my post to add a section titled “Transmission losses”.

      3. Timing. Concurrent needs across Europe make the case for, not against, greater energy storage capacity in order fully to exploit renewable energy generation.

      4. Surplus power. My post on Modelling of wind and pumped-storage power demonstrates that an over capacity of a factor of 5.5 (“massive” maybe) of wind power generation capacity in proportion to peak demand (operating in a system with 1.11 peak-demand-days of pumped-storage hydro) would provide 24/7 power in the weather conditions of 2014. It is a mistake to close the existing fossil fuel generators because we’ll need them kept operational and perhaps “mothballed” for emergency power. Whether it takes “a generation” to implement 100% renewable generation and supply, really depends on how much of a priority we make it.

      5. Chicken and egg. It’s not true that we can’t use power from renewable generators until the energy storage via pumped-storage hydro-schemes are available. We could use fossil fuel power stations to back-up renewables until such time as the energy storage capacity becomes available.
      As my modelling demonstrates, the reservoir can be filled up in a little over a day with the pumps operating at full power and Europe will have the power as and when it increases its renewable generator capacity.


  9. Firstly, I would like to congratulate the Scottish Scientist for his ambitious thinking. One needs to be very ambitious to provoke great changes that we need.
    Secondly, I would like to ask the members of this discussion if you would be interested to help me organizing the first Conference on Large-Scale Pumped-Storage in Scotland. This way we can invite industry players and present our projects and ideas for how this energy storage technology can contribute to the UK energy sector.
    Any ideas of sites for such conference? I would imagine Scotland to be the most appropriate location.
    Kind regards,


    1. A very warm welcome to you Julian to my blog and especially honoured are you in the comments to this post concerning a large-scale pumped-storage design proposal – a subject in which you have exceptional experience and expertise.

      I have already commented above about your proposed large-scale pumped-storage and linked to your post Energy Storage Solution for the UK: Large Scale Pumped-Storage Site – by Julian Hunt – published on The Energy Collective – the world’s best thinkers on energy and climate.

      I have also been privileged to receive from you a couple of emails attaching several files detailing your scientifically sound approach to engineering design, supported throughout by a meticulous technical rigor and colourful presentation, all of which prove further testament to your outstanding abilities in this field. Well done!

      As I intimated to you in my reply email, I and no doubt many others, would value all of your ideas for large-scale pumped-storage becoming more readily accessible on the internet, via links and internet searches. So please do blog post, reply comment or otherwise publish your thoughts because you have leadership to offer us Julian, of that I am sure.

      I welcome your proposal for the first Conference on Large-Scale Pumped-Storage in Scotland and I am curious to see what future interest there might be in such a thing.

      Meanwhile, I believe that there is so much more which we can all do to publish our respective project proposals on the internet, perhaps even collaborating on internet presentation – via, say, a multiple-expert-authors “Large-scale pumped-storage” blog – so as to demonstrate a growing unity of principles and approach. Here I have in mind, the exemplar of the “Energy Matters” blog, authored by both Euan Mearns and Roger Andrews.


  10. I live in Inverness and I think this is a good example of an idea approached from one narrow view point. I commend the effort and vision though.

    Until we have major land reform in Scotland this project, and the many others such as Coire Glas, these projects are generating millions for absentee land owners. What is Scotland for? If we export capital as we have been doing so for centuries then we can only blame ourselves.

    Much of the land in Strathdearn is owned by absentee Swedish land owner Sigrid Rausing. Fine, but until the community gets a controlling stake in all of this it shouldn’t happen.

    I am shocked at this link:

    It appears that this guy thinks you can get a 600m head from a height difference of 300m. Is there is something I am missing here. The biggest head in Scotland right now is 462m at Loch na Lairige.


    1. Welcome Donald. Thank you for bringing to this discussion your view point and the special interest of the residents of Inverness, especially concerning the sea-side elements of the scheme, such as the sea-side pumping and turbine station, which offers the shortest route to the sea if located somewhere, as per my map, by the sea at Inverness.

      I say “if” because the requirement for the scheme is primarily to connect to the sea somewhere convenient. Whilst locating the pumping station on the coast of the Inner Moray Firth, the Firth of Inverness, offers the shortest route, which appears to be the most convenient and economical, nevertheless a somewhat longer route locating the pumping station further up the coast of the outer Moray Firth, perhaps nearer Nairn or Findhorn, could be considered also if necessary.

      I consider myself to be a supporter of major land reform and no defender of the privileges of absentee land owners to obstruct the best land use as would benefit the people.

      I trust that the communities of Inverness and Strathdearn would be fully informed and consulted at every stage along the way and would be guaranteed to be stakeholders and beneficiaries of the Strathdearn Pumped-Storage Hydro Scheme and that any and all locals dislocated or inconvenienced by the requirements of construction would be generously compensated.

      My view is that control, over this scheme and all else in Scotland, should be democratic, according to laws made and consented to by the Scots.

      My view is that Scotland is for the Scots, for us, for “we, the people”.

      This project would require a major import of investment capital into Scotland. Any capital outflow from Scotland to compensate an absentee Swedish land owner may, I surmise, be more than offset by investment by Sweden into this scheme. Sweden has much more to gain, as does every country in Europe, if this scheme goes ahead, than if Sigrid Rausing is allowed to veto it.

      Julian can defend the claims of his own project more authoritatively than I, but to quote him

      “an upper reservoir with a water level of 300 metres above sea level can be created. As the water is drained from Loch Morar its altitude could reach as low as -300 metres. This results in a height difference of 600 metres between the two reservoirs”

      I think you may be missing Julian’s plan to drain Loch Morar to below sea level, so that when empty, the surface level is minus 300 metres, below sea level.


      1. Yes but that still doesn’t give you a head of 600m as the water on the downstream size of the turbines is 300m below the surface. I see where he gets his 600m from but fear basic physics may prove to be an obstacle.

        I hadn’t seen his idea to empty Loch Morar. That is so far from reality that there is more chance of me winning the lottery tonight. It’s Sunday and there is no lottery on. The ecological damage would be huge.

        The landownership issue, I think there should always remain a 51% controlling stake at community level. Also, I would be in favour of a legal requirement which meant that the community, however you define that, gets 51% of the revenue. No landowner should control this.


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