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!

Cruachan @ 7.1 GWh stores 10 billion times more energy than this TV remote battery. Strathdearn @ 6800 GWh would store 10 billion times more energy than this car battery.

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.


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

  1. [This comment previously posted on wrong thread]

    December 30, 2015 at 4:46 am

    I had a brief look at your pumped hydro scheme. I’d suggest and alternative design. I’d suggest connecting to Lochness by tunnels and with an underground power station. 620 m average hydraulic head and ~ 20 km horizontal. You can add incrementally in future.

    Problem with your design:

    1 Pumping seawater up to the upper late will almost certainly not get past environmental concerns.

    2. There are limits on amount and rate of drawdown for environmental reasons, so cannot use all the storage volume. I’d suggest you assume 10 m active storage depth.

    3. You cannot get the hydraulic head in canals the is necessary to get the required flow rate. You need pipes and/or tunnels

    4. If the high pressure penstocks are on the surface the thickness and cost of the steel pipes is prohibitive, so the power station and high-pressure tunnels need to be underground

    5. Most of the tunnel length can probably be unlined tunnel, so cheaper than steel pipes on surface.

    6. However, 20 km is probably too long for conventional pumped hydro – calculate the mass of water in the tunnel and the power needed to accelerate it from 0 to 3 m/s in say 5 minutes.

    You might be interested in my post on a conceptual 9 GW, 400 MWh pumped hydro scheme connecting existing reservoirs in the Australian Snowy Mountains Scheme . It is not viable but many people have learn’t a lot from reading and discussing it. The reviewers comments are also very informative, as are many of the comments.


    1. ScottishScientist,

      Here’s a very rough estimate of the cost of a 6.4 GW pumped hydro project between your dam and Loch-Ness by factoring from my conceptual Tantangara-Blowering pumped hydro scheme (link in previous comment). This does not include the cost of the dam. You could consider this as the first stage of a staged development. Key assumptions:

      Average hydraulic head = 620 m
      Tunnel distance = 20 km
      Tunnels = 3 x 12.7 m diameter
      Flow velocity = 3 m/s
      Flow rate = 1132.7 m3/s in each tunnel
      Head loss = 9 m
      Power = 6.4 GW
      Total estimated cost = $8 billion
      Cost per kW = $1,200/kW

      I suspect this estimate is too low.

      Also, as pointed out in my previous comment, 20 km tunnels are probably too long for pumped hydro.


    2. Welcome to my Scottish Scientist blog, Peter!

      “I had a brief look at your pumped hydro scheme. I’d suggest and alternative design. I’d suggest connecting to Lochness by tunnels and with an underground power station. 620 m average hydraulic head and ~ 20 km horizontal. You can add incrementally in future.” – Peter Lang

      The problem about using Loch Ness as the lower reservoir is that there is insufficient water in Loch Ness to take full advantage of the site in terms of energy storage capacity.

      The upper reservoir can hold up to 4.4 billion metres-cubed of water but Loch Ness only holds 7.4 billion metres-cubed of water, so to fill up the upper reservoir from Loch Ness would only leave 3 billion metres-cubed of water in Loch Ness, only 40% of the original volume which would likely prove to be unpopular and unacceptable.

      “1 Pumping seawater up to the upper lake will almost certainly not get past environmental concerns.”- Peter Lang

      Care to elaborate why not? Before you do though, please read about Wikipedia – Okinawa Yanbaru Seawater Pumped Storage Power Station which pumps seawater up to its upper reservoir and must have got past environmental concerns anyway.

      “2. There are limits on amount and rate of drawdown for environmental reasons, so cannot use all the storage volume. I’d suggest you assume 10 m active storage depth.” – Peter Lang

      What? What “limits”? What “environmental reasons”? Give me an example of a pumped-storage facility so limited, and a link so I can read about it.

      “3. You cannot get the hydraulic head in canals the is necessary to get the required flow rate. You need pipes and/or tunnels” – Peter Lang

      Yes you can get the hydraulic head in the canals that is necessary to get the required flow rate. Not only that, but I even published in my “Canal” section how to calculate the hydraulic head –

      • 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

      and I also published a table of results for the 2-way head-loss (which is twice the one-way hydraulic head) with canal width.

      I can only presume you are in denial about the application of the Manning formula to determine hydraulic slopes and heads.

      “4. If the high pressure penstocks are on the surface the thickness and cost of the steel pipes is prohibitive, so the power station and high-pressure tunnels need to be underground”- Peter Lang

      Well there are plenty of pictures of pumped-storage hydro schemes with pipes on the surface which can been viewed from an image search on Google proving you wrong about that Peter.

      “5. Most of the tunnel length can probably be unlined tunnel, so cheaper than steel pipes on surface.” – Peter Lang

      Tunnelling has a cost and unlined tunnels can collapse and that can be very expensive and time consuming.

      “6. However, 20 km is probably too long for conventional pumped hydro – calculate the mass of water in the tunnel and the power needed to accelerate it from 0 to 3 m/s in say 5 minutes.” – Peter Lang

      Well no worries because my scheme does not require a 20 km tunnel or pipe. A 30 km canal takes the water to a well-head about 5 km from the sea-side pumping station.

      “You might be interested in my post on a conceptual 9 GW, 400 MWh pumped hydro scheme connecting existing reservoirs in the Australian Snowy Mountains Scheme ” – Peter Lang

      Yes I am interested in other such schemes and welcome people posting links to them. So thank you for that and thank you too for your comment here.


  2. Just on one of the points above. There are environmental reasons and guidance regarding draw down. E.g. SSE are allowed, by SEPA I presume, to alter the level of Loch Ness through the Foyers scheme by “4 inches” if memory serves me correctly.

    Given the number of hydro schemes already influencing the level of Loch Ness I reckon one as big as that mentioned above is not likely to get through planning or feasible as the River Ness could not handle the additional flow.


    1. Welcome back Donald.

      I think the point you are talking about was this one

      “2. There are limits on amount and rate of drawdown for environmental reasons, so cannot use all the storage volume. I’d suggest you assume 10 m active storage depth.” – Peter Lang

      “What? What “limits”? What “environmental reasons”? Give me an example of a pumped-storage facility so limited, and a link so I can read about it.” – Scottish Scientist

      That point, yes?

      Well my scheme published here in detail doesn’t propose to draw-down any water whatsoever from Loch Ness. Not one drop. Rather my scheme uses the sea only as its lower reservoir. By the way, one can “draw-down” all the water one likes from the sea and its level would not go down measurably. So there are no environmental limits on “draw-down” from the sea, that I know of.

      It was Peter Lang, a commentator here yesterday for the first time who was commenting after his brief look only at my scheme, who suggested an “alternative scheme” daring radically to re-design my scheme to draw-down water instead from Loch Ness, rather than from the sea.

      What I took umbrage at and wanted clarification about was Peter Lang’s apparent suggestion, reading his point “2” that my design could somehow not use all the storage volume in the new upper reservoir, because in my design, which takes water from the sea, it certainly can use all the storage volume and in no way would the active storage depth in the upper reservoir be limited to “10 metres”, but would be unlimited and the upper reservoir could be drained entirely, with an active storage depth of 300 metres!

      It is really for you Donald, if you so wish, to take up with Peter Lang his own suggestion of using Loch Ness in a radically redesigned version of my scheme – so different it is barely recognisable as the same scheme – if that’s what the two of you want to discuss.

      But I sincerely hope that none of the two of you would dare to suggest here, commenting on my blog post, which details my design, which uses the sea only as a lower reservoir, that my design would have environmental draw-down limits of “10 metres” or whatever imposed upon it, OK?


      1. I’m no scientist or scholar, but I did design and build what I was later informed was the largest autonomous building in the UK, powered by wind, hydro & solar…
        But I will say that I think this proposal would have an incredible effect on Scotland’s future prosperity.
        Not only as a massive income generator via its electrical output, but also through tourism, and as a natural result of such a specialized project… off-shoot specialized projects which would also lead to a dramatic reduction in reliance on fossil fuels both home and abroad!
        And with regards to planning… Planning can always be gained when there is a will, and a goal!
        Funny how tens of BILLIONS of funding can be gained for HS2, for Trident 2, for foreign wars etc, but I suspect a project such as this will be ignored by Westminster because on completion, it dramatically enhances Scotland’s ability to be autonomous.
        So when people reply with negative comments, I would say this to them…
        Suggest solutions, not problems. Be part of the answer.

        This project is viable, and would take huge effort and funding… and is worth incredible value, especially when compared to projects such as Trident 2!

        Liked by 1 person


        You have to have an operational range – In this case it is effectively some 49% of the volume., and is about 28 metres difference in height. The reason is in the link, in the form of the silt that is carried in the water and which needs time to settle out each time the system is cycled.

        If you absolutely red-lined this proposal and ran the upper reservoir at those speeds and quantities, right down the bottom, you would be sucking thousands of tonnes of rock, mud and boulders the size of buildings right into your civil infrastructure – Namely, the canal – As well as all the dead marine life that got pumped up there in the first place.

        You could build this thing, I don’t doubt that. You could even use it, exactly once. Then you’d have to clean it all out and repair it.


  3. The purpose of this comment is to “reduce the emissions of twaddle” (to borrow a term from David MacKay’s book ‘Sustainable Energy – without the hot air’, p viii.


    • Generating capacity: 255 GW
    • Energy storage capacity: 6,800 GWh
    • Flow rate: 51,000 m3/s [the equivalent of the discharge flow from the Congo River, only surpassed by the Amazon!]
    • 300 m high dam with crest at 650 m elevation
    • Bottom reservoir is the sea
    • 30 km canal, 51,000 m3/s, triangular cross section with 1:1 side slopes, 170 m wide, 85 m deep, manning value 0.013, velocity 9.8 m/s, head loss 11.1 m (each direction).

    Comments, Issues, Criticisms:

    The World’s biggest-ever pumped-storage hydro-scheme, for Scotland? is not viable. Even if we assume a highly optimistic 15% average capacity factor the LCOE would be >10 times higher than LCOE of nuclear power. However, 15% capacity factor is virtually impossible if using power for pumping from weather dependent renewables. In fact, even if it could buy electricity for free, it would still need to sell it at around 10 times the cost of nuclear to be viable.

    Reasons why the 255 GW Inverness seawater pumped hydro proposal is impractical and not financially viable:

    1. Could never be financially viable – LCOE is ~10x the LCOE of nuclear.

    2. Therefore, it would never get funded.

    3. If built, it couldn’t buy renewable energy cheaply enough and sell at high enough price to pay for the scheme.

    4. Ignoring costs, the capacity factor, if powered by weather-dependent renewables, may be 1% to 15% at best.

    5. Capital cost of a hydro plant (not pumped hydro) 255 GW @ £10/W = £2,550 billion (say £3 trillion for your seawater pumped hydro project) (DECC, ‘Electricity Generation Costs 2013’, p67).

    6. Add capital cost of transmission (255 GW x 2000 km x £500/ = £255 billion.

    7. Total overnight capital cost = ~ £3.255 trillion (i.e. ~ £12.5/W).

    8. LCOE = £1,050/MWh (NREL ‘Simple LCOE Calculator’ , inputs: £12.5/W, 40 year life, 10% discount rate, 15% capacity factor, £104/kW.yr FOM, DECC, ‘Electricity Generation Costs 2013’, p67).

    9. Add: buy excess wind and solar power at say £100/MWh (DECC, ‘Electricity Generation Costs 2013’, p34) when available (= £133/MWh after pumping efficiency losses @ 75%); total LCOE = £1,183/MWh.

    10. Why would any rational buyer buy electricity from the scheme at £1,183/MWh instead of from nuclear power at around £93/MWh? (DECC, ‘Electricity Generation Costs 2013’, p33)?

    11. Even if an investor could be persuaded to invest over £3 trillion in your concept, how long would it take to build? 20 years, 30 years? Adding interest during construction would probably double the total capital cost that has to be recovered over the life of the plant.

    12. Environmental issues with pumping sea water into a reservoir at 630 m elevation that then infiltrates into the ground water and pollutes it with salt water (and some sea life that survives) would almost certainly preclude environmental approval.

    13. The purpose of the well is not explained? What is its volume? How many hours of water can it hold at 51,000 m3/s?

    14. The canal would be hugely expensive, prone to disruptions and impractical for many reasons.

    15. What is the land elevation profile along the centre line of the canal? How long would the canal be if it followed the contours? How much cut and fill would be required? Bridges across valleys?

    16. The land surface along the canal route seems to start at 300 m elevation at the well, fall to 267 m at Moy and rise to 350 m at the base of the dam. So the ground surface falls 33m and rises 87 m to the base of the dam . How is this going to be levelled? The cost will be enormous.

    17. How deep does the canal have to be to get the required flow rate in both directions? (e.g. 85 m + 11 m = 96 m deep at each end and 91m in the middle?)

    18. What is the cross section topographic profile at say 100 m intervals along the line of the canal? How much excavation is required for a 91-96 m deep by 170 m wide canal on the side of steep sided valleys?

    19. How will landslides, debris slides and erosion by freak floods be prevented for the life of the project?

    20. What will be the diameter of the pipes, and the steel thickness needed to hold the internal pressure at 300 m static head plus dynamic head? What is the estimated cost of the steel pipes?

    21. How many turbines and penstocks will you need for 255 GW generating capacity? – e.g. 500 turbines at 500 MW each (250 at sea level and 250 at base of dam)? Where would you fit them at the base of the dam? Underground? Cost?.

    22. How large would the two power station be with 250 x 500 MW turbines in each – e.g. 80 times ‘Tumut 3’ (6 x 250 MW turbines) – see photos:

    23. Cost of dam, canal, penstocks, pump-generating station?

    24. How long does it take to change from pumping to generating?

    25. Why would any rational utility buy electricity from the scheme at £1,200/MWh instead of from nuclear at around £93/MWh? (DECC, ‘Electricity Generation Costs 2013’, p33).

    26. Rough guestimate of uncertainty in cost estimate: -50% to +200%

    27. The generating capacity and/or storage capacity is overstated. Either the system is operated with the dam kept near full for maximum head, in which case the generating capacity is ~255 GW but the storage capacity is ~550 GWh, not 6,800 GWh. Or the system is operated to use all the storage in which case one would have to assume that the available head is with reservoir near empty because an operator would have to guarantee 95% reliability for his peaking power. Thus, the gross head for power generation is 300 m, so the generating capacity is ~132 GW and the storage capacity ~5,500 GWh. You should not claim 255 GW generating capacity AND 6,800 GWh energy storage capacity.

    Main Point

    No doubt there will be many errors in this and valid criticism about some details I’ve stated, but the main point is that the scheme is about 10 times too expensive compared with simply buying reliable nuclear power.

    The excellent 2015 ERP report ‘Managing Flexibility Whilst Decarbonising the GB Electricity System, also shows that energy storage is hugely expensive and ineffective. The ERP analysis shows that nuclear power is the cheapest way for GB to meet its 2030 CO2 emissions targets (e.g. Figure 14).

    The ERP analysed the cost to largely decarbonise the GB electricity system by 2030 with a wide variety of technology mixes. The ERP report is co-chaired by Prof John Loughhead FREng, Chief Scientific Advisor to DCEE. ERP members include a broad spectrum of stake holders from electricity industry, academics, government agencies and environmental NGOs. The ERP analysis considers and does sensitivity analyses on important inputs and constraints that are rarely included in analyses intended for informing policy analysts regarding policy for a whole electricity system.


    1. I was intrigued to read your proposal on pumped storage. While at Strathclyde University doing a Post Grad. our team, were tasked with storing wind energy. We came up with pumped storage using existing hyro schemes, which gave a potential storage capacity of 514GWh the link to our article is Storage Available. The main draw back is that these schemes are owned by one major energy company. They have their own pumped storage agenda. All the UK pumped storage schemes are owned by the same energy company. It is rumoured within the industry that prices as high as £50,000 per MWh were paid to Foyers for 90 secs, while old Longannet was struggling to get £11/MWh on a Friday afternoon. Unfortunately it is all about how much subsidies, grants or guaranteed payments per KWh that can be extracted from the government.
      Unlike most people I worked on the construction of some of the hydro schemes. I served my apprenticeship with Glenfield and Kennedy who made all of the Sluice Gates, Needle Valves and Butterfly valves for all the Hydro schemes constructed in Scotland. Starting with the Galloway schemes and finishing up with Cruachan. It is not about have we the capacity to store renewable energy, we do. It’s about who pays for it and how much.
      Bring back Nationalisation


      1. Hi Gilbert and welcome to my Scottish Scientist blog.

        You didn’t successfully link to your “Storage Available” page hosted with Strathclyde University’s Energy Systems Research Unit (ESRU) but I have been aware of the page since at least when it was linked to from daryanenergyblog Loch Ness monsters of energy storage.

        So I took the liberty of editing your post to add the link to that “Storage Available” page. Your Post Grad team article pages don’t seem to have links to a title page, only an “Overview” page, but with no title.

        What is the title of your post-grad team’s article, anyway?

        Without an obvious title which can be read on all, or indeed any, of your web pages, it makes it difficult to reference your team’s article in a standard way.

        This image is from my “Modelling of wind and pumped-storage” post which shows that only 160GWh of energy storage would be needed, along with 33GW of maximum wind power, to serve a peak demand of 6GW.

        With the realisation of 514GWh of potential pumped-storage hydro energy storage capacity that your article suggests, Scotland’s pumped-storage hydro could back up wind power to serve a peak demand of at least 3 times more peak demand than that, maybe 19GW, enough for when Scotland has electrified our heat and transport too.

        However, your page simply lists claimed pumped-storage hydro potential for 14 different sites, without describing what additional work is required at each site, for example in terms of having to build new lower reservoirs (which conventional hydroelectric schemes don’t need) to achieve pumped-storage hydro operation.

        Neither does your page suggest how much storage capacity could be achieved by changing the conventional hydroelectric turbines for pumped-storage turbo-pumps (or keeping the old turbine and adding a new pump), in sites where there is already something of a lower reservoir there.

        It’s not normally possible simply to swap out turbines and replace them with turbo-pumps because the pump needs to be housed underground far enough below the level of the lower reservoir to create enough pump input hydro-pressure to prevent cavitation.

        It would be interesting to know what scale of engineering work is required at each of those 14 sites to make good on the claimed potential. Then perhaps the costs of such enhancements might be estimated against the cost of building completely new schemes at undeveloped sites, whether Strathdearn, Coire Glas or elsewhere.

        We certainly do have the capacity to store renewable energy, the government should borrow from the central bank, courtesy of the nation’s savers, costing nothing to the taxpayers and electricity consumers, to invest in pumped-storage hydro as national renewable energy infrastructure.

        If there is to be a new nationalised entity created to provide energy storage services for the National Grid then I would like to suggest the title – the National Energy Storage Service (NESS).


        1. The title was “Storing the Wind“. While at Strathclyde .I came across the North of Scotland Hydro Board Annual Reports from 1946 to 1952 they are housed in the main Library These reports are not financial reports but engineering reports, listing each hydro scheme, with area to be served, storage capacity. in essence all the technical data needed to justify building the scheme. The records are only available to Post Grads on request. they are housed in an upstairs annex with its own librarian.
          The schemes I looked at had an upper reservoir, with the discharge into an existing loch.
          The owners of Loch Sloy have plans on the drawing board to build a pumped storage unit adjacent to the existing hydro Station. Similar to cruachan. Inside the mountainside. this would require a new tunnel to be drive, up to the catchment reservoir. I don’t know if it has been to planning yet.
          While at Strathclyde the team attended a lecture at the Institute of Electrical engineers, where we were informed as far back as the 1970’s. SSEB had plans drawn up for a pumped storage station on the Ben Lomond side of the loch, with the reservoir being near the summit of Ben Lomond. Early on they realised this was a non Starter, and that was before the creation of the National Park
          RE-engineering works for these sites. We realised new stations would require to be built. All we were trying to show was that Scotland had the potential to store all the renewable energy it could produce.
          The new Beauly to Denny Grid up grade is complete, but can it handle additional pumped storage.
          I Have a photograph taken of Glenfield and Kennedy Heavy Engineering workshop every thing in it is hydro related From the 14ft-6inch butterfly valves for the Snowy Mountain Scheme in Australia The photo was taken in 1955. it also shows parts of needle valves, roller sluice gates, etc and me. Unfortunately my printer won’t scan. my e-mail address is perhaps we could meet up


          1. Gilbert,

            Thank you for this comment. I loved this bit: “From the 14ft-6inch butterfly valves for the Snowy Mountain Scheme in Australia The photo was taken in 1955.” I was on the coffer dam for Guthega Dam when the diversion tunnel was opened in about 1951 or 1952. Then we went into the headrace tunnel which had just started excavating. We went in about 100 m (no hard hats, not safety equipment in those days). I was about 5 years old. I remember it to this day. The Resident Engineer (a Norwegian) gave me a 2 ft length of diamond drill core (granite). I had it at home for many years and it influenced my life. Guthega was the first hydro plant to be built in the Snowy Mountains Scheme. It was built first because it could be constructed without affecting the overall design of the rest of the scheme. The overall design of the scheme was still in a state of flux and any other development could have compromised the options. Much to tell about all this. It’s a fascinating story. If interested, there is an excellent book called “Engineering Features of the Snowy Mountains Scheme”. It contains all the engineering and contract details including costs and dates for each contract. It’s not easy to get any more. I got a copy second hand for a friend (now a professor) who worked with me on BC Hydro and other projects in the 1970 and 80s.


          2. Gilbert seems to be the only one on the web calling that site “Storing the Wind”. I did however find it referenced in a couple of academic papers, for example, like this.

            Day, G., Foote, P., McCloy, D. & Wilson, G. 2009, ‘Scotland Wind Power and Pumped Hydro Potential’ ESRU, The University of Strathclyde, Glasgow, [Online]:

            But although I have searched and I can find neither title (“Storing the Wind” / “Scotland Wind Power and Pumped Hydro Potential”), nor any other title, on the site itself, nor any indexing to Gilbert’s website on the Strathclyde University Energy Systems Research Unit site, though it may be indexed somewhere, under another title, it is not at all easy to find.
            Thanks to Gilbert for the additional information.
            Well I think I will leave it for now to Peter Lang, if he wants, to email Gilbert Wilson. Then you two old-timers can reminisce about the golden age of pumped-storage hydro and exchange photos, arrange for reunions etc. as you please. 😀
            I’m off back to my Fortress of Solitude / Bat Cave / Prison Cell and good luck in trying to find me for a meet up.


  4. I commend the schemes ambition and vision. It would be interesting to reconceptualise this project as a store of winter wind for summer usage. Relatively small pumps and turbines using relatively small amounts of fresh water from Loch Ness pumping a lot and generating a little in the seasons with the most wind, to later generate a lot and pump a little in the seasons with least wind. It would be a completely different project but with far far less engineering and capital needed, and far less environmental impact albeit not minor, with the loss of the upper Findhorn Valley being the principal issue.
    There is a 600MW sea water pumping station being planned in Northern Chile where I’m currently based, and the local fishermen are very concerned about the impact of sea life from the protozoa and larvae being hoovered up and pumped to 750 metres where they will be exposed to temperature differences and slight differences in salinity, as well as the pressures and velocities of the pumps themselves.
    The outflowing of a sterilised saline river Congo into the Moray firth could possibly create an ecological deadzone in that area. In Chile the project overcame some of these concerns by lining the upper reservoir with plastic sheeting to minimise chemical changes to the water composition from the higher soils. In Scotland the lining may also be required for the different reason of protecting the groundwater and soils in the upper valley itself.
    The reconceptualisation I suggest would overcome the majority of these issues, as well as changing the economic profile of the project very substantially in a favourable way.
    In general I’m not a big fan of pumped hydro, or any large scale hydro. The loss of entire valleys and the impact of massive engineering and construction projects are rarely fully mitigated! However I do recognise the enormous transformative potential of energy storage on the rest of the electrical generation and distribution system. The problem really is that pumped hydro is often the best of a bunch of old energy storage technologies. However there is very interesting work being done all over the world on developing new energy storage solutions such as flow batteries, heat batteries, compressed air batteries, fly wheels and much more. Any new pumped-hydro scheme would have to carefully consider the trajectory of these substitute technologies, any of which could render a 1 Trillion pound investment uneconomic before construction was even complete.
    I myself am part of a team working on a prototype compressed air technology which radically improves efficiency and cost over previous generations of AA-CAES systems. We’re aiming to be able to make more details public in the next few months. So if you are interested in investing in clean, cheap, reliable Energy Storage solutions that are easy to site and permit, let me know so we can keep in touch.


  5. After reading an article in Scottish Energy News by Professor Paul Younger, entitled “With the closure of Longannet, Scotland has become the first area of the UK to take a serious gamble with electricity supply”, I wrote to Professor Younger to bring the details of my “Strathdearn Pumped-storage Hydro Scheme” proposal to his attention.

    I am pleased to report that Professor Younger has just now replied to me by email in the following terms.

    • "Thanks for contacting me. I am very keen on pumped storage having spent years running a project at Cruachan), so enjoyed reading this.

      My immediate reaction is that there will be at least four wicked issues:

      1. Buildability of a canal of this magnitude through such terrain, with all the breaches of local drainage and transport routes this would entail.

      2. The sheer cost of the scheme.

      3. The introduction of sea water far inland, into the headwaters of one of Scotland’s most cherished salmonid rivers. This would necessarily entail loss of spawning grounds, and any leakage of the saline water could badly compromise the ecology of the Findhorn.

      4. Flood management: the Findhorn has the second-highest flood flows in Scotland (after the nearby Spey), and most of these originate in the headwater area you suggest impounding. Re-directing the flood runoff would entail a lot more canal construction beyond that needed just to shift the sea water.

      Best wishes

      Paul Younger

      Professor Paul L Younger FREng, FRSE
      Rankine Chair of Engineering, and
      Professor of Energy Engineering
      School of Engineering
      James Watt Building (South)
      University of Glasgow"


    1. Well done Professor Paul L Younger, FREng, FRSE. Thank you for your excellent, short, succinct, clear statement of what would be obvious to any engineer with hydro experience and others with expertise in energy, economics and financing of electricity systems.


  6. Well, my 2 ct also
    a) the proposal shows, that, if necessary pumped storage of nearly any size can be built, if politically wanted.
    b) there are technical risks, but for technical risks there are usually solutions.
    c) So what remains is the economic question. To keep in mind, there are >150.000 GWh useable storage capacitys in existing dams in Europe. Most of them are not pumped storages, but storages which store the energy of natural water flows, but to many of these Storages pumped schemes can be added, with additional storages below, or more often with additional storages above existing lakes, or by connecting existing lakes.
    d) So there is no foreseeable need to build new big dams like the proposed one. There is enough capacity in existing lakes, with just a little additions around them. The need to balance renewable also becomes smaller the bigger the grid becomes which one looks at.
    e) There are already HVDC-Transmissions with 1100kV in China.
    f) The diameter of the cables used for HVDC Transmission can be increased, there are no real technical limits to increase the cross section by factor 1000 So the losses along the grid can be adjusted as low as it is economical reasonable. The problem is many people have a block in the head excluding all cross sections above 250mm², without any technical reason. It is correct that bigger cross sections were rarely used because it was not necessary to transport so much power over so long distances. But this is far away from not being possible.


    1. Hi Mark and welcome to my blog. 🙂

      Your expectation of “3365 GWh” for the energy storage capacity for the Strathdearn pumped-storage hydro scheme is an underestimate, arrived at most likely because you have erroneously assumed the head always to be “of only 300 m”, whereas 300 metres would be lowest operation head that only applies when the upper reservoir has drained to almost empty.

      As the reservoir fills up the head rises, to a maximum of 650 metres in the super-sized version of the Strathdearn scheme. Then the average head of the 4.4 km3 of water is 570m.

      Also your calculations that arrive at a necessary energy storage for the UK of “17,464 GWh” are an overestimate. You have assumed –
      “A wind powered Britain would need 171 GWe of wind”
      – whereas my scientific computer modelling has previously recommended

      annual maximum wind power = 5.5 x peak demand power

      which for a UK peak demand of 52.5 GW would be 290GW, which is 119GW more wind power than the mere “171GW” which you have assumed.

      This graph, again from my modelling, based on wind and demand data from April 2015, suggests that 1,400GWh would be all the energy storage capacity needed to serve British April 2015 power needs from a simple wind power and pumped-storage hydro system.

      Line graph of power grid and energy store timeline – April, UK

      I have today applied my computer spreadsheet model to the wind and demand data from Mark’s selected time period – September 2014 – and was confounded to discover that my (up until now) recommendations of

      store energy = 1.11 days x peak demand power
      annual maximum wind power = 5.5 x peak demand power

      would not work well, the reservoir would run dry and a power deficiency would require the import of power into the system to meet demand.

      Wind Pumped-storage September 2014 (50%)

      After further research today, I found that with my new recommended

      store energy capacity = 1.5 days x peak demand power
      annual maximum wind power = 7 x peak demand power

      the system has enough wind power and energy storage to cope with the very low wind conditions of September 2014.

      Wind & Pumped-storage September 2014 UK 370GW 1,900GWh - 50%
      Wind & Pumped-storage September 2014 UK 370GW 1,900GWh


  7. After the Oroville Dam crisis, should we risk new big dam projects?

    Oroville Dam Spillway, February 2017
    Oroville Dam Spillway, February 2017

    BBC: Oroville Dam risk: Evacuated not allowed home immediately

    In my opinion, yes, we should risk new big dam projects world-wide.

    New pumped-storage hydro schemes are needed for energy storage to back-up intermittent renewable energy generators, such as wind turbines, in the cleanest, greenest possible way. (Cleaner than bio-mass burning though requiring much more capital expenditure and investment, admittedly.)

    The problem with the Oroville Dam is a poorly designed and constructed spillway system from the day it was built in 1968.

    The main spillway looks like it has been built using lined-canal engineering – with foundations sitting on the sloped ground underneath being subject to erosion and landslide. So it looks like the spillway has failed in exactly the way a road would fail where a sinkhole has opened up underneath it.

    The main spillway design should have followed aqueduct engineering practice – meaning built as strong as a bridge with deeply driven pile foundations, highly resistant to erosion and landslides.

    The spillway design job can be made easier with appropriate choice of route for the spillway – helpful are gentle slopes and bedrock conveniently close to the surface. Looks like the Orville Dam designers took the shortest, cheapest route for their main spillway.

    There’s no reason to assume that in future, the best project managers would make such a poor job of designing and building our big dam projects.


    If you can promote your hydroelectric scheme when all about you
    Are losing theirs and blaming it on the weather
    If you can trust your science when all men doubt you
    But make allowance for their doubting too

    My proposed more powerful Strathdearn Pumped-Storage Hydro Scheme has some similarities to the Oroville-Thermalito Hydro-electric Power Complex.

    The 2 Dams (Strathdearn & Oroville) would be about the same size.

    The Strathdearn Dam could be built as high as 300m high x 2000 m long.
    The Oroville Dam is 230m high x 2100 m long.

    The impounded reservoirs would coincidentally be the same volume of 4.4 km3.

    Both schemes feature a power canal.

    The Strathdearn power canal would be much wider, longer and the flow rate 100 times higher, up to 51,000 m3/s.
    The Thermalito power canal is tiny by comparison with a small flow rate of only 430 m3/s.

    (By comparison, the maximum flow rates we have seen thundering down the Oroville Dam Spillway in recent days of 100,000 cfs = 2830 m3/s, are only about 1/18th of the maximum flow through the mighty Strathdearn Power Canal)

    The Strathdearn scheme could be powerful enough to serve all of Britain’s needs for energy storage and the needs of some of our European neighbours too.

    The UK peak demand is about 55GW but the Strathdearn power capacity could be super-sized to supply up to 180GW – that’s plenty for future expansion needs too.

    The Oroville-Thermalito complex supplies only about 1GW. That’s very little in comparison to what Strathdearn could supply.

    So although the 2 dams – Oroville VS Strathdearn – are roughly the same size and the water impounded the same volume, the flows of water are very much more powerful in the Strathdearn scheme.

    Although the Oroville Dam is the tallest dam in the US, the Oroville-Thermalito hydroelectric scheme is a modest scheme when considered next to the colossal scale of the Strathdearn Pumped-Storage Hydro Scheme.


    1. Welcoming today’s post “How California’s electricity sector can go 100% renewable” on Energy Matters, I’m posting now here on my blog 2 concepts for California Energy Storage which I had developed and first published elsewhere in July 2017.

      Lake Tahoe for energy storage
      Lake Tahoe for energy storage

      Edmonston Pumped Storage Hydro Scheme
      Edmonston Pumped Storage Hydro Scheme

      Whereas Energy Matters has today suggested serving California from the south from Mexico, it is also worth considering the option of serving California from the north from British Columbia in Canada, which has the ideal geography for pumped-storage hydroelectricity schemes, such as the adjacent freshwater Lakes Chilko and Tatlayoko; sites for sea-water schemes are plentiful in B.C. too.

      BBC – “Sturgeon signs climate agreement with California”

      I do hope that First Minister Nicola Sturgeon and Governor Jerry Brown and the people of Scotland and California are duly grateful and that they do appreciate these credible suggestions to use pumped-storage hydroelectricity schemes for the large scale of energy storage which is required for the transition to 100% renewable energy.

      These serious and scientific energy storage proposals are modestly suggested in a manner that contrasts with the incredible hyperbole which accompanies the flogging by Tesla and others of inadequately small and far too expensive batteries as a “sticking plaster” “snake oil remedy” that cannot be fit for the purpose of achieving our ambitions to support low carbon energy to resist climate change.

      Elon Musk – that don’t impress me much.


  8. It is all about economics, it would likely be a lot cheaper to build an inter-connector to Norway and or Iceland and use a ‘cheaper’ hydro power scheme built where there are better mountains and shorter tunnels required for High Head schemes than Loch Strathdearn, (and believe it or not this is what is happening with National Grid investing in a non regulated businesses overseas in Norway).

    I am all in favour of renewable electricity generating but I don’t wish to pay over the odds for my electricity. My business has to compete globally and having higher electricity costs and taxes CCL (Climate Change Levy) used to subsidise high cost re-newables make it more difficult. From a global perspective it would be better to invest in the Congo River Hydroelectric scheme 12 – 20 GW installed capacity which would run throughout the year and move the energy hungry businesses of Aluminium production there from all around the world and close it down fossil electricity production elsewhere used for Aluminium manufacture. Lets use a bit of Lateral thinking.


  9. In the course of my spirited defence of this proposal on Energy Matters last week, I made a few remarks about the alternative fresh-water variants of this scheme, although my final comments in our exchange haven’t as yet been approved by Euan for publication on his blog so I will quote here from my remarks there and reveal one of my two final comments.

    “The location of the site for my Strathdearn Pumped-Storage Hydro-Scheme – particularly the upper reservoir, dam and power canal are located south of Inverness, rather than “south of Loch Ness”, in an area quite well-defined by the “Inverness South” ward of Highland Council.

    The residents thereof would, I trust, be well-compensated for any compulsory land buy-outs, relocation costs or disruption caused by the re-engineering of the local environment.

    The default version of the scheme proposes to use sea water. However, fresh water variants of the scheme are possible, using fresh water from Loch Ness and the River Ness.

    Aerial photo of Lake Oroville, Oroville Dam, the spillway, and the Feather River

    The volume of Lake Oroville which is impounded by the Oroville Dam, which so spectacularly over-topped a couple of years ago, is about the same “giant” volume as the upper reservoir of the Strathdearn scheme at its grandest scale, as I commented upon at the time in my blog.

    The Oroville–Thermalito Complex is a group of reservoirs, structures, and facilities located in and around the city of Oroville in Butte County, California. The complex serves not only as a regional water conveyance and storage system, but is the headwaters for, and therefore perhaps is the most vital part of, the California Department of Water Resources’ State Water Project, the world’s largest publicly built and operated water and power development and conveyance system.”

    So a scheme of that grand scale is demonstrably not “utterly bonkers environmental destruction on a grand scale” but is an entirely responsible re-engineering of the environment with irreplaceable benefits for the people, on a grand scale.

    I propose that Strathdearn would be paid for by additional government borrowing, not by the tax-payer and not ever by diverting funds intended for “hip replacement operations and care for the elderly” or the like.”

    “Assuming an active or live storage reservoir volume of 4.4 billion metres-cubed, then to fill or empty the upper reservoir from or to the lower reservoir in a day would require a flow rate of about 51,000 metres-cubed per second.

    The discharge rate of the River Ness would not limit the operational flow rate between the upper and lower reservoirs of any of the fresh water variants of the scheme which I have in mind.

    Whatever the flow rate of the River Ness is, it is not an issue and not a problem and I might suggest a bit of a red herring as far as the options for the Strathdearn scheme are (concerned).

    There was no good reason me to consider the discharge flow rate of the River Ness in the first place and no good reason to remind you or anyone else of that either.

    If you’d like to claim that the River Ness discharge rate could be a game-changer or particularly relevant for Strathdearn pumped storage hydro fresh-water variants then you’ve not explained why you think that?”

    “It seems you are not aware that river discharge rate is a major issue at Coire Glas that is a much smaller scheme than your proposals. I don’t have time to engage in this kind of pointless exchange.”
    Euan Mearns

    “Actually, Euan, I am very well aware of the issues at Coire Glas which empties into Loch Lochy, NOT into the sea.

    Even the fresh-water variants of Strathdearn include a power canal etc. which BY-PASSES the River Ness, allowing for whatever controlled overflow into the sea is required.”

    “Yes, but when you pump the reservoir Ness will run dry.”
    Euan Mearns


    Only with the fresh-water scheme variant which uses Loch Ness as the lower reservoir would the River Ness “dry run”, admittedly.

    In which case, the Caledonian Canal could be extended for another 20+ miles along the length of Loch Ness to allow for continued navigation.

    However, with the other fresh-water variant which uses an artificial fresh-water lagoon constructed in the Moray Firth, the levels in Loch Ness are UNCHANGED and the River Ness DOESN’T “run dry”.

    In this case, the outflow from the River Ness would be diverted into the fresh-water lagoon.

    The discharge flow rate from the River Ness would NOT limit the operational flow rate between the upper reservoir and the fresh-water lagoon but would only determine at commissioning how long (months) it takes to fill the fresh-water lagoon before the scheme can be operational at full energy storage capacity.


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