14 votes

Can gravity batteries solve our energy storage problems?

12 comments

  1. [12]
    cmccabe
    (edited )
    Link
    Of course the answer to the title question is “no” (someone was going to make that remark), but it looks like they very well could serve as part of the solution.

    Of course the answer to the title question is “no” (someone was going to make that remark), but it looks like they very well could serve as part of the solution.

    "What goes up, must come down" – this is the immutable Newtonian logic underpinning gravity batteries. This new field of energy storage technology is remarkably simple in principle. When green energy is plentiful, use it to haul a colossal weight to a predetermined height. When renewables are limited, release the load, powering a generator with the downward gravitational pull.

    5 votes
    1. [2]
      stu2b50
      Link Parent
      I wouldn't say it's a straight up "no". It is the, perhaps more bland, "maybe", after reading the article. There's no outright reason brought up to think it couldn't be the primary method of...

      I wouldn't say it's a straight up "no". It is the, perhaps more bland, "maybe", after reading the article. There's no outright reason brought up to think it couldn't be the primary method of energy storage for most grids in a renewable future.

      4 votes
      1. skybrian
        Link Parent
        It seems like to answer this you need to know what the costs will be, and also the costs of the competing energy storage solutions that people will come up with. I think it will be difficult to...

        It seems like to answer this you need to know what the costs will be, and also the costs of the competing energy storage solutions that people will come up with. I think it will be difficult to pick the winners.

        2 votes
    2. [9]
      Eric_the_Cerise
      Link Parent
      Curiously, I got a pretty clear-cut "yes" out of reading it ... they're comparable to lithium batteries in efficiency, cheaper, more environmentally friendly, and they last longer. About the only...

      Curiously, I got a pretty clear-cut "yes" out of reading it ... they're comparable to lithium batteries in efficiency, cheaper, more environmentally friendly, and they last longer. About the only "maybe" I read is getting comfortable with using them at scale and en masse.

      Obviously, this is not going to become 100% of the solution, but they sound like a great new tool for the toolbox, and they could become the first choice in most circumstances.

      What led you to conclude the answer was "no"?

      3 votes
      1. [5]
        Greg
        Link Parent
        I can't remember where I originally saw this, maybe even here, but it's now the first think I think of for these systems as it highlighted a few things I'd wondered about and several more I hadn't...

        I can't remember where I originally saw this, maybe even here, but it's now the first think I think of for these systems as it highlighted a few things I'd wondered about and several more I hadn't thought of: https://youtu.be/iGGOjD_OtAM

        As it happens, the video's talking not just about the same tech but the same actual company as the BBC article. I don't have the expertise to judge either side's claims well, but the counterpoints seem broadly to be:

        • Making concrete blocks emits a large amount of CO2

        • Concrete blocks will degrade from repeated stacking/unstacking. Environmentally friendly packed-earth blocks will degrade much faster

        • One giant stack will only hold two days of output from a single turbine

        • The above-ground high precision stack is very susceptible to wind, and the circular six-crane arrangement is highly suboptimal

        • Putting the whole thing in a rectangular pit with a gantry crane solves those two issues

        • If you're building earthworks of that level anyway, why not just fill the pit with water and use a pump?

        • In fact, in a lot of environments you can even use much larger natural features rather than digging new holes!

        To my non-expert ear, it seems a compelling argument for pumped hydro over other forms of gravity storage.

        6 votes
        1. [2]
          Omnicrola
          Link Parent
          I have not watched the video, but OP's article mentions making blocks out of recycled material. Pumped hydro seems like a good tool in the toolbox, but also seems much more dependent on a...

          I have not watched the video, but OP's article mentions making blocks out of recycled material. Pumped hydro seems like a good tool in the toolbox, but also seems much more dependent on a location's geography. The tactic of using gravity seems much more flexible to me. There are going to be some ideal materials (concrete, iron) to use for a gravity battery, but it also easily scales and adapts technologically. You can literally throw trash into a bucket, hoist it up, and connect it to a dynamo. A country can source whatever heavy material is easily available and use it.

          3 votes
          1. Greg
            Link Parent
            It's only four minutes and presents the ideas better than I can as a middleman, if you happen to be somewhere that you can spare the time! Like I said, though, I'm certainly no expert in the...

            It's only four minutes and presents the ideas better than I can as a middleman, if you happen to be somewhere that you can spare the time! Like I said, though, I'm certainly no expert in the field.

            My read wasn't that the concrete issue specifically was a killer, just that (a) the designs in the PR video had visible problems, and (b) solving those problems, at best, leads to a situation where you're digging a big pit anyway and would be better off filling it with non-potable water rather than whatever other ballast for a number of reasons.

            3 votes
        2. KapteinB
          Link Parent
          Seems like someone at Energy Vault saw that video as well, because their newer EVx design looks like it won't collapse catastrophically in a storm. The video ends on the note of "don't build this,...

          Seems like someone at Energy Vault saw that video as well, because their newer EVx design looks like it won't collapse catastrophically in a storm.

          The video ends on the note of "don't build this, build pumped hydro instead", but as the article explains, that's simply not an option many places in the world.

          The article also mentions another company that plans to repurpose old mine-shafts for underground gravity batteries, and yet another company developing a different water-based solution.

          3 votes
        3. FlippantGod
          Link Parent
          I think most out of service open pit mines that could be swiftly converted to energy storage should not be filled with water, as nasty stuff might leach? And I imagine water is not suitable in...

          I think most out of service open pit mines that could be swiftly converted to energy storage should not be filled with water, as nasty stuff might leach? And I imagine water is not suitable in many locations.

          I don't know if open pit mines are suitable for energy storage due to geographical location.

          2 votes
      2. [2]
        cmccabe
        Link Parent
        I shouldn't have added that comment as it turned out more of a distraction than anything. I only meant to preempt the cliched response that a title question always implies an negative answer. I'm...

        I shouldn't have added that comment as it turned out more of a distraction than anything. I only meant to preempt the cliched response that a title question always implies an negative answer. I'm far from an engineer, but gravity storage definitely seems to me a good candidate for storage of green energy. Plus, I have a pet interest in technologically simple solutions, and a mechanical system, even at this scale, checks that box for me. (Some day I'll post about my server that runs on human lifted weights and gravity storage (I have to get past the long-delayed planning stages first though)).

        4 votes
        1. aphoenix
          Link Parent
          I just wanted to let you know that I immediately understood what you were saying / doing with your response and also enjoyed the article.

          I just wanted to let you know that I immediately understood what you were saying / doing with your response and also enjoyed the article.

          2 votes
      3. NaraVara
        Link Parent
        They're only practical at scale. The "lithium battery efficiency" assumes you've got basically a parallel power generation system to store and release the potential energy. This is useful for...

        About the only "maybe" I read is getting comfortable with using them at scale and en masse.

        They're only practical at scale. The "lithium battery efficiency" assumes you've got basically a parallel power generation system to store and release the potential energy. This is useful for large scale utilities but it's unlikely to be helpful for a home or even a huge office park once you factor in parts and maintenance costs.

        I also think most of these novel systems like lifting stuff with cranes are going to be less useful than the simple, tried and true methods. These would be pumped hydro or just sending carts full of rocks up a hill.

        2 votes