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China built a 40-story tower that stores wind power by stacking concrete (boingboing.net)
submitted 2 months ago by to c/technology@lemmy.ml
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[–] [S] 20 points 2 months ago (33 children)

I would expect it would be pretty similar, in each case you're lifting a mass to create some potential energy and then draining it later. I can't imagine the work involved in pumping up water is all that different in terms of efficiency from lifting concrete. The advantage with concrete is that you can do it in places where you don't have huge amounts of water to spare though.

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  • [–] 7 points 2 months ago (16 children)

    Water is way, way cheaper, and concrete requires a massive amount of water.

    Just saying.

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  • [–] 9 points 2 months ago (2 children)

    Water also doesn't get damaged through constantly moving it.

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  • [–] 5 points 2 months ago (1 child)

    Thats a pretty fucking big on. Also, the technology to "turn a wheel" to create electricity.. pretty fucking established.

    And.. god forbid, if the community you are in ends up needing water more than electricity, well, you've got a bunch stored and ready for other uses.

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  • [–] [S] 3 points 2 months ago (12 children)

    the article says it's recycled though...

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  • [–] 3 points 2 months ago (3 children)

    I mean I would guess it's for energy density not environmental savings of any kind.

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  • [–] [S] 4 points 2 months ago (2 children)

    I would guess it's because it's likely very low cost and easy to build, but there are obvious environmental savings that fall out of it naturally.

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  • [–] 1 point 2 months ago* (1 child)

    savings that fall out of it naturally.

    sigh.... Buh dim tish.

    On the topic, I really doubt it's about savings at this scale, which is very much proof of concept. I mean it could be but at this stage it's more important to show it's potential. And for some thing that's gonna run for thousands of cycles..

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  • [–] 2 points 2 months ago* (7 children)

    I mean, unless they're directly cutting up old buildings into the final block shape for this (which would be a nightmare to actually do), it doesn't actually help that much. You can't practically un-make concrete and turn it back into that slurry that comes out of the mixer truck, AFAIK all "recycled" concrete means is old concrete gets crushed into fragments and used in place of gravel. But the gravel is not the truly problemic part, you still need more cement to bind those fragments into your desired shape, which releases carbon and consumes water.

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  • [–] [S] 2 points 2 months ago (6 children)

    But you do that once, and the thing lasts 35 years, somehow I can't imagine environmental impact would be worse than mining and refining rare earths for regular batteries here.

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  • [–] 2 points 2 months ago (5 children)

    I can’t imagine environmental impact would be worse than mining and refining rare earths for regular batteries here.

    I mean it depends on the energy density. Where the batteries go. Can they be just "slapped into" existing infrastructure? Can they rare earths be used effectively indefinitely once mined, and on and one and on.

    An inability to imagine isn't a form of evidence.

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  • [–] [S] 1 point 2 months ago (4 children)

    Energy density has nothing to do with this. It's the cost of how much pollution refining the rare earths and making batteries produces vs the amount of pollution associated with construction of a building with pulleys that move weights up and down.

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  • [–] 2 points 2 months ago (3 children)

    Energy density has nothing to do with this.

    No it absolutely does, and it matters because:

    It’s the cost of how much pollution refining the rare earths and making batteries produces vs the amount of pollution associated with construction of a building with pulleys that move weights up and down.

    If an entire building could be supplied with a few elevator shafts and some weights, because the energy density of the system is so high, it would be silly not to do so. But the energy density of these systems isn't remotely close to that. Where as yes, a building absolutely can be built with batteries as a part of it to support its typical duty cycle.

    Gravity is just not a particular energy dense form of storage. Its not really debatable. And like you said, building buildings comes with all kinds of other forms of pollution. Not to mention, we could be building them to house people, not pulleys and weights.

    Its an idea that sounds good, but once you engage with it seriously, its limits become obvious. Pumped hydro will almost always make more sense. A big tank at the top and a big tank in the basement, and bam. Battery built. not to mention you've got a semi-permanent back up reservoir now built, which could help with flood control, drought tolerance, fire control, all kinds of other things. And you don't need to build new buildings for this. They can go into/ on existing buildings.

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  • [–] [S] 1 point 2 months ago (2 children)

    I would imagine that hydro would actually have to deal with more friction leading to more energy loss.

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  • [–] 4 points 2 months ago (13 children)

    High friction is my guess.

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  • [–] [S] 13 points 2 months ago (12 children)

    I mean, it's not like concrete is scraping on the walls going up and down, it's on a pulley system which would be efficient in terms of doing energy transfer. The article mentions round-trip efficiency above 80 percent, so I'm not sure pumping water could be much more efficient than that.

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  • [–] 7 points 2 months ago (5 children)

    https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/

    The main problem with gravitational storage is that it is incredibly weak compared to chemical, compressed air, or flywheel techniques (see the post on home energy storage options). For example, to get the amount of energy stored in a single AA battery, we would have to lift 100 kg (220 lb) 10 m (33 ft) to match it. To match the energy contained in a gallon of gasoline, we would have to lift 13 tons of water (3500 gallons) one kilometer high (3,280 feet). It is clear that the energy density of gravitational storage is severely disadvantaged.

    It seems the problem is not necessarily one of conversion efficiency, but rather of scale. In order to store significant amounts of electrical energy using mechanical means, you need to move a lot of weight. Manufacturing the concrete blocks requires money and raw materials, and a pulley system robust enough to move them around wouldn't be cheap either. The pumped storage hydroelectric systems which currently provide the vast majority of our grid energy storage partially circumvent this expense by taking advantage of natural bodies of water and advantageous topography.

    That being said, it's definitely a fascinating concept and one worth exploring. But there are well established difficulties that explain why this type of energy storage isn't already widespread.

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  • [–] [S] 1 point 2 months ago (4 children)

    right, it only makes sense if you do it at large scale

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  • [–] 4 points 2 months ago (3 children)

    it only makes sense if you do it at large scale

    Or rather, it specifically might NOT make sense at scale. It might only make sense in middle scales, where there isn't a topographic advantage to use, but the requirement is more than batteries can support.

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  • [–] [S] 1 point 2 months ago (2 children)

    What I meant is that you need to build a unit of a certain size before it becomes efficient enough to be practical.

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  • [–] 1 point 2 months ago (5 children)

    What about friction within the pulley?

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  • [–] [S] 2 points 2 months ago (4 children)

    Again, they state over 80% efficiency in the article. So, that's your answer.

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  • [–] 2 points 2 months ago (2 children)

    Well, this 80% efficiency is what they are targeting not what the system will do. The test system Energy Vault build in a MUCH smaller form factor had a round-trip efficency of 75%

    The EVx ™ system is projected to achieve an impressive round-trip efficiency exceeding 80%. Source

    Only time will tell if they can reach 80% with a bigger system or at all. If they actually manage this it would be a decent alternative to Hydrodams in areas where these are just not possible since it would be a similar round-trip efficency.

    Pumped storage systems have a round-trip efficiency of about 80%, which is competitive with battery storage. Source

    In my opinion these systems are inferior to fly wheel energy storage (can reach up to 90% round trip efficency Source) but might still be an option depending on price.

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  • [–] [S] 1 point 2 months ago

    Fly wheels are pretty cool too, it could be that this is just easier to build and maintain though. I imagine the primary considerations are around how cheap it is to produce and whether it holds enough energy to make it worthwhile.

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