Britain's Largest Battery Is Actually A Lake

  • Published on: 05 November 2018
  • Dinorwig Power Station, otherwise known as Electric Mountain, is a pumped-storage hydro station in Llanberis, Wales. And yes: it's Britain's largest battery. Here's how it works, and why some of the things you think you know about TV pickups might not be so true any more.

    Thanks to all the Engie team! More about them:

    Public tours of Electric Mountain are closed until mid-2019, but you can find details here:

    Camera op: Ryan Priestnall
    Editor: Michelle Martin (@mrsmmartin)

    I'm at
    on Twitter at
    on Facebook at
    and on Instagram as tomscottgo
  • Runtime : 4:56
  • tom scott tomscott amazing places dinorwig llanberis electric mountain engie


  • Frank Suhai
    Frank Suhai   21 hours ago

    I have to say this is basically a dam which needs to be recharged by pumping the water back into the reservoir. Stupid. Build a dam!

    PRIYANSHU ASHIYA   1 days ago

    Can someone please explain- the amount of energy generated by falling water from higher reservoir should be equal to work done by pumps in getting water back to the reservoir . So, how are they generating energy exactly?

  • Vasilis GHC
    Vasilis GHC   1 days ago

    Quick question: how much of the generated energy does it take to pump the water back at the start? So what is the net gain of energy?

  • ClarinoI
    ClarinoI   2 days ago

    I saw the title: Britain's Largest Battery Is Actually A Cake. Have to say I did a double take.

  • Krishnendu Chatterjee

    I don't understand that the energy needed to pump back the water at night would be higher than the energy one can extract while that water rushes down during the day. How does the energy math work out? Smells like a perpetual machine.

  • Middle Class Chemist

    Fun fact: If you explore deep enough into the disused slate quarries above the station, you can hear the hum of the turbines beneath your feet, through many meters of rock.

  • Audio World
    Audio World   4 days ago

    I have a friend that works there. It truly is a magnificent piece of engineering.

  • GoodLuckLima
    GoodLuckLima   4 days ago

    Isn't this inefficient, as you pump the water you just shot down? you have to have lost energy somewhere in that exchange.

  • Sphinx Rising
    Sphinx Rising   4 days ago

    Ok, so, it produces power when drained, so, how much energy dose this system consume when it reverses?

  • Paul Productions
    Paul Productions   5 days ago

    Those fast spinning turbines are intimidating. Like damn I can feel the energy even sitting on the toilet watching this video.

  • Flexable
    Flexable   1 weeks ago

    Should you really consider chemical as potential energy? I'd call that chemical energy.

  • John Keepin
    John Keepin   1 weeks ago

    Well presented. I was already aware of this one. I think the system has changed a fair bit since it was originally built, especially with the advent of significant wind and solar generation. What’s not mentioned is that one of it’s ‘near neighbours’ is a redundant power station - Trawsfynedd, an old pair of Magnox reactors. Whether that site will ever be redeveloped along the lines of Hinkley Point C or not is uncertain. It may have been that hydro storage was helpful in the past when the old nuclear station was operational, as they were not able to cope with rapid changes. Probably depends on the market value (of power station output), but most of those like to run at ‘base load’, and it could be that a certain amount of it’s ‘surplus’ output was temporarily stored in Dinorwig, in effect.

  • Mr.Nerd3.14
    Mr.Nerd3.14   1 weeks ago

    Electric Mountain sounds like the name of a place in a Pokémon game.

  • AustiPriest
    AustiPriest   1 weeks ago

    They briefly mentioned it at the end of the video, but storage mechanisms like these are going to be crucial to developing renewable/intermittent energy. Not only can these stations activate when solar/wind electrical production are lagging, they can also store any excess energy that's produced as well! So say you overbuild your solar capacity, so that on the sunniest of days when solar is producing more power than is actually needed, that excess power is stored. Then at night, when the sun is down, that power is then sent back into the system. I do think storage systems like this are the future.

  • zapfanzapfan
    zapfanzapfan   1 weeks ago

    The lake is just for show, the real power source is the Balrog :-)

  • hetspook666
    hetspook666   1 weeks ago

    Engie the company that change its name like every year.cofly engie gti gdf suez to name a few

  • Moesia Testecles
    Moesia Testecles   2 weeks ago

    What if we heavy weights instead of water? Just dig some holes in the ground and raise/lower heavy things for energy storage.

  • rob murray
    rob murray   2 weeks ago

    Here I am on a lockdown Saturday.... Been "asked" by my other (better?) half to paint..... Coming up with more feeble excuses every minute as to why I can't..... All because I have been sat watching this channel continuously for the last 5 hours! 5 hours! Mr Scott, you are a legend and a true joy to listen to (a cross between David Attenborough's soothing voice and Johnny Ball's enthusiasm).Thank you!

  • Nissim SLAMA
    Nissim SLAMA   2 weeks ago

    We have the same thing here in Israel :-)

  • Evil Otto Jr. Productions

    I never knew about that water hammer thing; the pipes in my house do it quite loudly because they aren't secured to anything at all apparently

  • James H
    James H   2 weeks ago

    Stupid title and stupid video. A 'battery' means stored chemical energy. This lake is just potential energy, it has nothing in common with a 'battery' at all other than they have to do with energy, which everything in the universe does.

  • Radu Cristian Dumitrescu

    What a waste of energy to run that pomps.But here is all about money.Only single thing to help is battery power packs to charge at night but engie does not want that.

  • Krato
    Krato   2 weeks ago

    If it uses gravitational energy then it technically isn't a battery because it doesn't use chemicals to generate electricity

  • Bob Cranberries
    Bob Cranberries   2 weeks ago

    That’s possibly the stupidest thing I’ve ever heard. there’s no way that will ever break even more or less make money.Must be heavily government funded or something

  • jocapoc
    jocapoc   2 weeks ago

    I feel like if UK made sense your channel wouldn´t be viable. Great content!

  • maxime aloe
    maxime aloe   2 weeks ago

    so Britain's battery is made by a French company...

  • Liam Tahaney
    Liam Tahaney   2 weeks ago

    I would call this the Sisyphus generator

  • dedium
    dedium   2 weeks ago

    this is too genius... why haven't i though of that......... this is amazing..

  • Grant Bitman
    Grant Bitman   3 weeks ago

    What an utterly inefficient use of resources. This has got to be the most wasteful means of electric generation.

  • Fraser Hughes
    Fraser Hughes   3 weeks ago

    Interesting you didn't mention the Russian hydropower station that blew up after it didn't account for water hammer

  • DiscoReaper
    DiscoReaper   3 weeks ago

    Similar configuration of pump & generate built in Ireland at Tourlough Hill in Wicklow Mountains outside Dublin

  • colin higgins
    colin higgins   3 weeks ago

    I was in charge of removing the last major bit of rock (in the draft tube valve gallery for those of a technical bent) in 1979 as a student engineer. Amazing place and even more awe inspiring when it was an empty hole with no machinery!