back to article Inside Electric Mountain: Britain's biggest rechargeable battery

From the outside, Elidir Mountain looks like an old industrial site that has returned to nature. The slopes facing the Llyn Peris reservoir have been hacked into terraces by slate quarrying – this was once the second-biggest quarry in the world, with 3,000 workers – but they are now peaceful. Only a few buildings at ground …


      1. MonkeyCee Silver badge


        The UK builds trains for Germany and the Netherlands. I get a Bombardier built small train twice a day normally :)

        1. John Brown (no body) Silver badge

          Re: Trains

          "I get a Bombardier built small train twice a day normally :)"

          Yeah, but isn't Bombardier a Canadian company?

          1. Peter Ford

            Re: Trains

            "isn't Bombardier a Canadian company?"

            Depends how you say it. I think they prefer "bom-BAR-de-ay" so yes: (French?) Canadian.

            If it were British it would be "BOM-a-deer"

  1. Valerion

    Went there a couple of years ago

    I loved the tour, the wife and kids were not quite so impressed. Damn non-geeks.

    The cafe served some very nice cake if I remember correctly.

  2. GrumpenKraut Silver badge
    Thumb Up

    For anyone interested in this kind of stuff, but down under

    Check out Snowy Hydro, it's really awesome. They used (IIRC) up to 60 thousand workers. They had to build the infrastructure in the first place!

    Let me add a "thank you" for the article. I'll surely go through those fine articles on the Reg before I visit the UK (admittedly no concrete plans yet).

  3. Booty003

    For those of you so inclined - there is an awesome Triathlon in this are called The Slateman. I have done it a few times and the run element involves running past the station itself and then trekking up said mountain and through some truly stunning scenery. The whole event has some beautiful views - well worth a look. The 2016 event is actually this weekend.

  4. Anonymous Coward
    Anonymous Coward

    Rate this article: 11 out of 10

    that is all

  5. Commswonk Silver badge

    Don't gloat yet awhile...

    @massivelySerial:While travelling I met a Californian who had discovered the "Amazing electric fast water boiling jug!!!" for the first time in his life.

    Seems he'd never seen a real kettle before because:

    240v x 13 amp ~ 3kW

    110v x 15 amp ~ 1.6kW

    While 3kW is more than enough to boil a litre of water during a commercial break, 1.6kW simply isn't. Gotta feel sorry for the yanks sometimes.

    I'd hold on to that "sorry" for a bit; if the rumours are true the EU Commission is itching to reduce the rating of kettles within the EU, much as it did with the size of vacuum cleaner motors. Just wait to see what happens after the June referendum.

    1. Yet Another Anonymous coward Silver badge

      Re: Don't gloat yet awhile...

      But if Britain leaves Europe it will have to join America and so will be forced to use 110v.

      1. MachDiamond Silver badge

        Re: Don't gloat yet awhile...

        The US may have a lower line voltage, but the residential installations are safer. I'm just amazed at what qualifies as "code" in the UK.

    2. Anonymous Coward
      Anonymous Coward

      Re: kettle

      Does the name Revd Adrian Kennard mean anything to you? He's a geek and he runs a boutique ISP and leads the BT fan club (not) and he has a personal blog. He wrote about kettles a few days ago. Conclusion: misreporting. What a surprise.

    3. John Brown (no body) Silver badge

      Re: Don't gloat yet awhile...

      "I'd hold on to that "sorry" for a bit; if the rumours are true the EU Commission is itching to reduce the rating of kettles within the EU, much as it did with the size of vacuum cleaner motors. Just wait to see what happens after the June referendum."

      Yes, they already did it to toasters! (Well, someone did anyway) FFS it takes bloody ages to get that first portion of toast out nowadays and the next lot isn't that much quicker. My feeling is that since so much heat rises up out of the toaster that having a lower heat for longer is more wasteful than a fast "blast" of high heat.

    4. fnj

      Re: Don't gloat yet awhile...

      @Commswonk - it's actually (nominally):

      230 x 13 = 2990

      120 x 15 = 1800

      So the ratio is 1.661, not 1.891.

      1. Richard 12 Silver badge

        Re: Don't gloat yet awhile...

        The UK might be 230VAC nominal, but almost everywhere is actually 240-245VAC.

        230VAC +10% -5%

        A lot of new builds are tapped high to allow for sag without retapping.

        1. John Hughes

          Re: Don't gloat yet awhile...

          That's how they fixed the difference between 240V in the UK and 220 in Europe. They both moved to 230.

          In fact nothing changed but the labels as 220V ~= 230 - 10% and 240V ~= 230 + 10%. Everyone is happy.

  6. TRT Silver badge

    I hear been camping in Wales many times...

    the last time, when we did a trip to Dinorwig, we were woken at 5am by the farmer coming round and banging on the tents saying "Everyone up! The river's rising... higher ground, people." And the time before that, which was after a charity trek up and down Snowden, the farmer didn't bother to get us up, and we awoke to water lapping over the top of the the bucket sewn-in.

  7. Prst. V.Jeltz Silver badge

    surely the "ad break power surge" is fading into the past now?

    with on demand blah blah , and timeshifting gizmos

  8. TRT Silver badge

    There is actually a company...

    called Di Electric.

    Di-Electric services

    Tel: 01443 834630

  9. Boris the Cockroach Silver badge

    Just dont go in the basement

    where they filmed "aliens"... there maybe a few left over eggs still in there.....

  10. fnj

    Just keeping it real

    Everybody going on about 110/220 V please get with the program. It's been 120/240 V nominal at the entry into the house in the USA for simply ages. It's actually only spec'ed +-5%, so anything in the range 114-126 V is in spec for the supply. Equipment must be capable of working without appreciable handicap anywhere from 110-130 V. Most computers and TVs are perfectly happy working with 90 V or less, up to at least 130 and very often over 240 without any circuit switching.

    I am informed that the UK is 230 V, so the ratio is not "over 2.0"; not even exactly 2.0, but rather less than 2.0.

    I have a very strong memory of reading that the nominal voltage in the US used to be 110/220, but that was at least 50 years ago. I cannot now locate any trace of information on the web to that effect.

    1. TRT Silver badge

      Re: Just keeping it real

      The UK tends to use 110 on building sites simply because it's less lethal and those places are notorious for cut cables.

      1. Uffish

        Re: 110 on building sites

        When I was working on a building site (a very long time ago) it was 110V with the centre tap connected to earth. Thus an exposed wire would only be at 55V wrt earth.

  11. crediblywitless

    Can I just say "one point thirty-two gigawatts?" More than enough to run a time machine.

  12. Anonymous Coward
    Anonymous Coward

    Remember it being built

    Whilst working as a trucker, I delivered the framing for the underground control room, from a fabrication specialist in Preston. was eerie driving down the access tunnel, to the massive undergorund cave at the heart of the mountain.

  13. This post has been deleted by a moderator

  14. RichardPSmith

    green lunacy

    pumping - generating - pumping - generating.

    Each time, what, 30% efficiency?

    This is not storing electricity, it is using it.

    1. cray74

      Re: green lunacy

      pumping - generating - pumping - generating. Each time, what, 30% efficiency?

      Pumped storage hovers in the 70-80% efficiency range between storing electricity (pumping with some efficiency loss through the 90%+ efficient electric motors) and generating (releasing water through the 90%+ efficient electric generators.) There are additional losses, like turbulence, heating, friction in pipes, etc. that bring you a bit below 80%.

      It's much better than, say, batteries. The only competitor on a similar scale is underground compressed air storage, though I might be forgetting another GW-scale power storage system.

      1. Vic

        Re: green lunacy

        The only competitor on a similar scale is underground compressed air storage


        I've not seen any figures for such a system - but I've pumped a lot of scuba cylinders in my time, and the losses due to adiabatic compression heating were *enormous*...


        1. Anonymous Coward
          Anonymous Coward

          Re: green lunacy

          "I've pumped a lot of scuba cylinders in my time, and the losses due to adiabatic compression heating were *enormous*..."

          Losses might well be proportionally enormous on that scale and for that purpose.

          If someone was using compressed gas for grid-scale energy storage it wouldn't be done quite the same way:

          "Liquid Air Energy Storage (LAES), also referred to as Cryogenic Energy Storage (CES), is a long duration, large scale energy storage technology that can be located at the point of demand. The working fluid is liquefied air or liquid nitrogen (~78% of air). LAES systems share performance characteristics with pumped hydro and can harness industrial low-grade waste heat/waste cold from co-located processes.

          Size extends from around 5MW to 100s+MWs and, with capacity and energy being de-coupled, the systems are very well suited to long duration applications."


          The engineering is tried tested and proven. The big snag is getting market pricing today (quarterly profits to be made, or else) to reflect a problem/solution a year or four down the road (no money to be made this quarter from stopping the lights going out in four years time).

          See also: Highview, Linde etc, e.g.

          [Linde is a company which, amongst other things, supplies high volume industrial gases, e.g. liquid nitrogen produced on-site by liquefying air]

          1. Vic

            Re: green lunacy

            Liquid Air Energy Storage (LAES), also referred to as Cryogenic Energy Storage (CES)

            OK that's not actually a compressed-air storage system as mentioned earlier. Rather interesting, though.

            Efficiency without scavenged heat/cold seems to be about 60% - which is higher than I had expected, TBH.


    2. Anonymous Coward
      Anonymous Coward

      Re: green lunacy

      Electrical plants can produce so much electricity per day.

      This allows you to store energy produced during the off peak hours and bring the generators on line during peak hours to distribute the "stored" electricity.

      Makes a lot of sense.

    3. MachDiamond Silver badge

      Re: green lunacy

      No, the efficiency is much higher than 30%. You also have to factor in that the National Grid has to switch off a lot of wind power at night due to over supply. Coal and Nuke plants don't like to be turned on and off frequently. If the excess power can be stored even partially, it's a good investment. The 12 second turn on time is very handy for accommodating peak loads. There isn't any other system that can do that.

      Eventually, it may be possible to supplement and then replace pumped storage with electric cars that can move power in both directions as needed. The business model will need to be worked out and there will be a need for people to be able to opt-out from time to time if they are planning on a long trip and need a full charge in their cars.

  15. Nonymous Crowd Nerd

    Just a little more needed!

    While it's quite impressive that the power generated is sufficient to keep Wales going for five and a half hours, I'm afraid we need a little more than that to be able to get all our power from renewable sources. To cover a spell of windless dark days in mid winter would need about five and a half weeks power for the whole of the UK.

  16. Sean o' bhaile na gleann

    Getting back to the subject of the article, I noticed a small 1-paragraph report in the Times last Saturday, to the effect that ' coal was burned last week for generating electricity in the UK. It all came from hydro or wind power.' (I'm not sure I actually believe that last bit). Due to many coal-fired power stations having been shut down, and the rest all down for maintenance, apparently. There was no mention of how much was imported from nuclear France, etc., but the report struck me as hugely significant. Worth far more than 5cm below the fold on page 5.

  17. nagyeger


    In case anyone ever tries arguing with you that lower powered kettles are more efficient... Please apply the following simple bits of physics: convection, radiation, evaporation.

    The longer the kettle spends getting from 30°C to 100°C, the more these sources of heat loss will come into effect, therefore low power kettles are better at heating the air, and less efficient in heating the water.

    (The icon is for a nice efficient way of heating /lots/ of water.)


    PS. Would someone like to test how hot a 25W fish tank heater (without a working thermostat) will actually get a typical fish tank? My guess is somewhere around 50°C, but I don't have a fish tank to test it these days.

    1. Anonymous Coward
      Anonymous Coward

      Re: Pot, kettle, black body

      No sensible person should try to argue that there's much of an 'efficiency' difference between kettles, in the same way that no sensible person will try to argue that there's much of an 'efficiency' difference between various forms of electric heating of the usual kinds (yes Rointe and similar, I'm looking at your garbage arguments).

      What might well be argued, and is valid, is that lower power kettles are more likely to motivate people to **only heat the water they need, when they need it** rather than heating a kettlefull, using a cupful, and wasting the rest. Because it takes longer (just in case anyone hasn't worked it out).

  18. MachDiamond Silver badge

    Now I'm boggin' for a cuppa

    Robert Llewelyn has a video posted of a tour of the plant on his "Fully Charged Show" YouTube channel.

    Amazing tech and a perfect compliment to wind power. Natural gas doesn't make sense as a back up for wind. To get a minimum start time for the NG plant, one has to use combustion turbines and it's much less expensive (more efficient) to just use combined cycle NG turbines all of the time and skip putting up the wind turbine. With pumped storage, it's a simple thing to push some water uphill when there is excess capacity in the grid.

    1. ShadowDragon8685

      Re: Now I'm boggin' for a cuppa

      I just read the titles of all of his Fully Charged videos and I couldn't find it. Was it taken down?

      1. MachDiamond Silver badge

        Re: Now I'm boggin' for a cuppa

        My mistake. It was on How do the do it? Which Robert hosted, but not this particular season.

  19. Alan Bourke

    Of course we've had one here in Ireland

    since 1974.

  20. Marketing Hack Silver badge
    Thumb Up

    Pumped storage is pretty useful

    I haven't been to Electric Mountain, but I have been to the Helms and Castaic pumped storage plants in California, and the one way up by Birney California, who's name I forget.

    They can be a bit hard on the local environment, because they take a lot of water and chew up a lot of fish life in the upper and lower reservoirs, but they are still a very useful option for peak and intermediate load generation. It's good to diversify generation sources anyway.


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