4 ms·

Scientists propose converting tall buildings into batteries

dexwiz 4y ago
Any high rise I have worked in seems to have a rotation of elevator engineers always fixing various shafts. In not so frequently used buildings, the elevators seem to be the first thing to degrade. I am no elevator engineer, but I assume they are not trivial to maintain. So my question: is this method worth the wear and tear on the elevator? While the shafts are already there, I assume lift specifications are much more inline with a few people, and not literal tons of wet sand, so they would need to be retrofitted. Also maintenance seems much harder on a closed-in elevator than a typical crane or a bridge crane over a pit.
- jaclaz 4y ago
  Though as well not an elevator engineer, I have some experience with cranes, bridge cranes and similar. Simplifying, any of these are a winch, any number of pulleys and support for them. Elevators normally are "direct drive", i.e. the winch is right over the shaft. In cranes there are normally a few pulleys to "move" the cable from the winch to the lifting point, but - additionally - cranes use sets of pulleys to demultiplicate the tension on the cable. Example: https://www.zoke-crane.com/posts/2708/ https://www.zoke-crane.com/posts/2708/ the more turns around pulleys you have the more you increase the lift capacity BUT at the same time you slow down the speed. In normal operation of cranes you change the way the cable goes around the sets of pulleys, if you have less weight to lift you use a more direct drive (and have more speed) if you have more weight to lift you use a less direct drive (and have less speed). In theory if an elevator winch (and cable) can lift 1 ton at (say) 3 m/s, it can also lift 2 tons (but at 1.5 m/s speed) by using a set of pulleys (it will also need double the length of cable, that the drum may not be able to receive) BUT you cannot change the cable path on-the-fly, and surely the beams that support the winch were designed for 1 ton, not 2. So you could devise a smart way to have small (1 ton each) containers of some heavy material (of course not wet sand, which is in practice the worst cause of corrosion for metal) more likely cubes made of concrete be loaded and unloaded (and translated horizzontally to and from storage). It is not like you can put that many of these 1 ton cubes on the highest floor of a tall building without structural consequences for the building, so it is not just a matter of replacing/retrofitting the elevator winch. There is a very clever similar idea/experiment using a crane and concrete blocks: https://www.wired.com/story/energy-vault-gravity-storage/ https://www.wired.com/story/energy-vault-gravity-storage/ but at least they built a dedicated plant.
  - dexwiz 4y ago
    I’ve seen this project, and the reason I mentioned bridge cranes was this critique. https://m.youtube.com/watch?v=iGGOjD_OtAM https://m.youtube.com/watch?v=iGGOjD_OtAM
    - jaclaz 4y ago
      Yep, but this is a (IMHO) better critique: https://cleantechnica.com/2022/04/20/energy-vault-loses-1-2-billion-40-market-cap-co2e-kwh-worse-than-natural-gas/ https://cleantechnica.com/2022/04/20/energy-vault-loses-1-2-...
      - dexwiz 4y ago
        Yeah thats a pretty good write up. Dude should have shorted the stock, would have made a pretty penny.

Any high rise I have worked in seems to have a rotation of elevator engineers always fixing various shafts. In not so frequently used buildings, the elevators seem to be the first thing to degrade. I am no elevator engineer, but I assume they are not trivial to maintain. So my question: is this method worth the wear and tear on the elevator? While the shafts are already there, I assume lift specifications are much more inline with a few people, and not literal tons of wet sand, so they would need to be retrofitted. Also maintenance seems much harder on a closed-in elevator than a typical crane or a bridge crane over a pit.

jaclaz 4y ago
Though as well not an elevator engineer, I have some experience with cranes, bridge cranes and similar. Simplifying, any of these are a winch, any number of pulleys and support for them. Elevators normally are "direct drive", i.e. the winch is right over the shaft. In cranes there are normally a few pulleys to "move" the cable from the winch to the lifting point, but - additionally - cranes use sets of pulleys to demultiplicate the tension on the cable. Example: https://www.zoke-crane.com/posts/2708/ https://www.zoke-crane.com/posts/2708/ the more turns around pulleys you have the more you increase the lift capacity BUT at the same time you slow down the speed. In normal operation of cranes you change the way the cable goes around the sets of pulleys, if you have less weight to lift you use a more direct drive (and have more speed) if you have more weight to lift you use a less direct drive (and have less speed). In theory if an elevator winch (and cable) can lift 1 ton at (say) 3 m/s, it can also lift 2 tons (but at 1.5 m/s speed) by using a set of pulleys (it will also need double the length of cable, that the drum may not be able to receive) BUT you cannot change the cable path on-the-fly, and surely the beams that support the winch were designed for 1 ton, not 2. So you could devise a smart way to have small (1 ton each) containers of some heavy material (of course not wet sand, which is in practice the worst cause of corrosion for metal) more likely cubes made of concrete be loaded and unloaded (and translated horizzontally to and from storage). It is not like you can put that many of these 1 ton cubes on the highest floor of a tall building without structural consequences for the building, so it is not just a matter of replacing/retrofitting the elevator winch. There is a very clever similar idea/experiment using a crane and concrete blocks: https://www.wired.com/story/energy-vault-gravity-storage/ https://www.wired.com/story/energy-vault-gravity-storage/ but at least they built a dedicated plant.
- dexwiz 4y ago
  I’ve seen this project, and the reason I mentioned bridge cranes was this critique. https://m.youtube.com/watch?v=iGGOjD_OtAM https://m.youtube.com/watch?v=iGGOjD_OtAM
  - jaclaz 4y ago
    Yep, but this is a (IMHO) better critique: https://cleantechnica.com/2022/04/20/energy-vault-loses-1-2-billion-40-market-cap-co2e-kwh-worse-than-natural-gas/ https://cleantechnica.com/2022/04/20/energy-vault-loses-1-2-...
    - dexwiz 4y ago
      Yeah thats a pretty good write up. Dude should have shorted the stock, would have made a pretty penny.