Why Scotland’s huge renewable energy production may need no huge energy storage breakthrough to flourish


My headline is a shameless rewording of the title of a US piece in CleanTechnica on March 4th, which naturally made me think of Scotland. Much has been said and written about the weakness in our massive growth in renewables, storage. I’ve already written about solutions already being developed in Scotland, such as batteries, conversion to hydrogen and the exploitation of more reliable offshore wind and tidal forces. For more on these see:

Storing Scotland’s over-production of electricity in 100Mw batteries

Europe’s biggest hydrogen-powered bus fleet and now the UK’s biggest hydrogen cell installation are both in Scotland

Re-opened Scottish dock to build state-of-the-art floating windfarm to begin to exploit Scotland’s 25% share of all of Europe’s offshore wind potential

As world’s largest tidal energy plant in Pentland Firth generates 1GWh which is enough for 700 000 homes, will Scotland become the most energy-rich country in Europe?

Always at the back of my mind, though, has been another technology, well-established here, which I’ve read little of in a Scottish context. You may have thought of it yourself (before seeing the photograph above) but before I get to it, see this from the CleanTechnica report based on the USA:

‘In the last couple of years, there has been a growing a number of news articles and blog posts published about energy storage, particularly in the form of battery systems. This interest is very reasonable, and the news is exciting because these systems can fill in wind power and solar power electricity production gaps.  However, it appears as though pumped hydro storage is being overlooked, with all the hype about batteries. It still has huge potential to help balance clean, renewable energy. In fact, all the discourse about battery storage seems to be supporting the idea that this form of storage is going to solve clean energy intermittency issues, but there are gaps in what batteries can provide, so let’s take a look at pumped hydro so we can see just how large a factor it could become.’


‘Pumped hydro storage’ is, as far as I can see, the same thing as out long-established hydroelectric power stations, such as the one at Cruachan. Here’s how the US system is illustrated:


I’m no technologist so is it just a hydroelectric power plant of the kind we have decades of working with? If so, why is this technology not being talked about for storage? My first reaction is that perhaps our hydroelectric power stations generate all the power they need by themselves to pump water back up for storage. There may however be other sites which would need the electricity from renewables to achieve their full storage potential. I don’t know. The US report suggests that there are potentially around 22 000 pumped hydro energy sites in Australia and that Germany already has plans to use the technology to store around 23Gw by 2050 so there must be something in this.

Finally, of course, there are environmental and safety concerns with battery storage while hydro is, to my knowledge, safer and more ecologically sound.

As in some earlier pieces, this is a social scientist dabbling in the physical sciences and technology but I know some readers are equipped to clarify or correct.


23 thoughts on “Why Scotland’s huge renewable energy production may need no huge energy storage breakthrough to flourish

    • johnrobertson834 March 6, 2018 / 5:16 pm

      Thanks, I’ve driven by it and wondered about the lack of drop compared to Cruachan.


  1. Holebender March 6, 2018 / 10:28 am

    Pumped storage is a bit more than just hydro-electric because the system has the capability of generating electricity AND feeding electricity into the turbines to reverse them and have them act as pumps to move water back up the hill. The technology’s been around for decades and it’s excellent but it does have some drawbacks; it requires a lot of real estate to build reservoirs and there’s a high initial capital outlay, for starters. I don’t know why it’s not talked about more than it is, though.


    • Alasdair Macdonald. March 6, 2018 / 12:04 pm


      As you say this has been around for almost as long as the hydro schemes have been going, with Cruachan being the most famous. Of course, the Second Law of Thermodynamics means that there are energy losses in all parts of the cycle, but, nevertheless, using the off peak electricity to pump the water back up replenishes the head loch and avoids the kind of seasonal variations in water level that occur, which can have an effect on sustaining the banks of the loch and also the ecosystem, because these schemes are always colonised by an ecosystem.

      The hydro dams were, of course a huge job creation scheme and, this could be one excellent way of providing employment. Of course, the opposition is mainly political, although there are ecological arguments, too. This raises issues of land ownership and the ‘sporting’ estates, so roll on land reform! It also raises issues about the so called ‘national (i.e. UK) grid, where we are in the ludicrous position that all of these places around Scotland producing various kinds of renewable energy are having to pay exorbitant costs to connect to the ‘national’ grid. It is politics much more than economics.

      The skills of the shipbuilding industry could be deployed to support and sustain a wave/tidal energy production system, which electrolyses seawater to produce hydrogen which can be piped ashore and distributed by a Hydrogen ‘national’ grid. Because of the corrosive saltwater environment, the infrastructure would require continuous maintenance and replacement, thus sustaining continuous jobs in the fabrication yards. Technology, would allow much of the corroded metals to be recovered and recycled into new parts for the infrastructure.

      Of course, the aforementioned Second Law would mean that there would always have to be some fresh materials brought in, the rate of usage of resources and the consequent ecological damage would be slowed.

      These kind of things, coupled with land reform could have a significant effect on repopulation of Scotland’s sparsely populated areas and would enable the population to grow. We will need specific Scottish powers over immigration to enable this to happen.

      Liked by 1 person

  2. Roland Smith March 6, 2018 / 10:28 am

    Google Craigroyston. Would have been biggest pumped storage in the UK until Westminster stopped NOSHEB building it. I did some ancillary IT work to do with the problem then of measuring the depth of Loch Lomond at various points.


  3. Alan M Johnston March 6, 2018 / 11:50 am

    During WW2 Churchill appointed Tom Johnston as Secretary of State for Scotland. He referred to him on occasion as King of Scotland. One of Johnston’s greatest achievements was to have areas identified for the building of dams for power generation. Many of these large reservoirs were built and are still in use. With pumped storage we should consider the following, at times of high electrical demand the water flows through the turbines from the dam generating the necessary power. At times of low demand, i.e. overnight, the pumps can then replenish the water in the dam by pumping eater from a lower “reservoir” such as Lochs Lomond,Awe and Ness. Given the ever increasing tidal power generation we have this is the perfect way to generate power. As we know the tides are a given. They are on a 12 and a half hour cycle and are so regular that we can tell what the tidal position of any part of Scotland will be for 1,000 years ahead. We can also tell the amount of water movement there will be with the same accuracy. Allow me to explain, the rise and fall of the tide can be ascertained with the same accuracy. There are “Spring tides” and “Neap Tides” . Spring tides are the ones with the greatest rise and fall. Neap tides are those with the smallest rise and fall. These are all determined by the positions of the sun and moon. Again, all very regular through the ages. The tides don’t rise and fall around Scotland at the same time. Its not like the hokie cokie. For instance, today’s times for the high tides at various places in Scotland according to the BBC weather site are as follows. Campbeltown-15.07, Oban-08.14, Wick-14.15, Dundee-17.35. That means there are tidal flows all around our coasts at all times, night and day. At times of low demand the reservoirs can be refilled by use of this excess power. There were other Hydro schemes identified but never built. Today we have the technology to make best use of our renewable resources. One last point, given that so many of our land owners spent so much time and effort clearing the glens there will be minimal disruption to people when the new dams are built and in fact many opportunities to repopulate now empty areas as a result of the opportunities.


    • Alan Gordon March 7, 2018 / 10:44 am

      All good points. I would add only two things and one is definately in the nerd/nitpicky class. First the nerdy one, the calculations for the tides are based on “tidal constants” and they are only good for 19 years, then they are recalculated. Doesn’t really affect your point of tidal flows around the country. Personally I would prefer pumped storage as far less better quality grazing or cropping land is lost from the alluvial areas.
      Yours the nitpicker.


  4. Marlene Halliday March 6, 2018 / 12:31 pm

    In the back of my mind I have the notion that one of the reasons for building a Scotland -Norway interconnector cable was so that Scottish renewable electricity could power Norwegian pumped storage schemes. There being a lack of suitable sites to build more pumped storage in Scotland. There are plans for the interconnector but I Haven’t been able to confirm the pumped storage bit of that memory. But there are grand designs to expand Norway’s pumped storage capacity and of course they have the billions to do it from their Oil Fund. https://www.greentechmedia.com/articles/read/norway-could-provide-20000-mw-of-energy-storage-to-europe#gs.2cpscVA


    • johnrobertson834 March 6, 2018 / 5:20 pm

      Interesting. I knew there were readers who knew more than I do on this. Thanks.


  5. Willie Hogg March 6, 2018 / 2:15 pm

    The.main problem is that the energy will be stored at times of low demand and released at times of peak demand. So there will be a huge markup between the purchase price and the sales price. Since these sites are in Scotland and Wales that is where the profit will made. However, battery sites could be located in England.


  6. Inverschneck March 6, 2018 / 7:23 pm

    Loch a Choire Ghlais is a scheme in planning that might interest @ 1500 MW it’s a beast.

    Click to access Coire-Glas-2017-Final-Exhibition-boards-Final-210617.pdf

    Planning was passed by the highland council quite the thing.

    The rumour is the developers (SSE) wanted unit price guarantees of half what the French/Chinese were getting for Brinkley point – they didn’t get it so they downed tools.


  7. William Henderson March 6, 2018 / 8:34 pm

    There is a problem with pumped hydro that no-one has mentioned in the comments – that is efficiency. Because of the nature of turbine technology the efficiency both of pumping and of generation is around 50% at best. This means that of all the energy devoted to pumping water to a height only about a quarter will be delivered to the grid during the generation cycle. Economically this is not sustainable and existing pumped storage schemes are justified only on the grounds that a quickly accessible source of power is needed for short term surges in demand. For this, combined gas turbine installations are better and cheaper as well as being more efficient.

    Hydro power really only comes into its own when it can harness the energy of very large rivers where water flow rates are guaranteed.

    Tidal power, as you mentioned, holds a huge potential for predictable power generation. The variation in output due to the behaviour of the tides can be overcome to a large extent by distributing the tidal stations geographically to take advantge of tidal times at different locations.


  8. Alan Gordon March 6, 2018 / 10:15 pm

    All good stuff. I think Cruachan was commissioned to make use of surplus, therfore cheap off peak electrcity from Hunterson nuclear to pump up to the reservoir. The turbines could act as pump as well as generator. The one in Wales, Ffestiniog? is a true pump storage system, it has no need for an electric supply to pump. My older boy works in Wales on renewable install and maintenance, and I’m sure I remember him saying it was something like 70 to 75% efficient. I and no doubt William H think this seems a bit too efficient. Maybe Welsh water is heavier when it comes down. Also remember Cruachan being about 3 times the output of the Welsh one, something like 350mw to 900mw+. Don’t know why I’m not more positive with the figures wiki will have them.


  9. johnrobertson834 March 7, 2018 / 9:47 am

    Apologies for the delay in approving many of these later and very useful contributions to the discussion. All very much appreciated. I think if you ‘follow’ the blog your comments go straight in.


  10. David Connelly March 8, 2018 / 12:07 pm

    This hydro-energy storage is a great system. The electric mountain in Snowdonia works well and is a tourism attraction . We have something similar here already which is decades old so why not build more. The Scottish National Investment Bank could fund the development and receive a percentage of the profits for the nation.


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