24 ms·

I never understood why wind turbine towers are built as hollow, tapered cylinders. Isn't the best mass-to-strength ratio acheived with truss/grid type structure

I never understood why wind turbine towers are built as hollow, tapered cylinders. Isn't the best mass-to-strength ratio acheived with truss/grid type structures, like in construction cranes?

lostlogin 1y ago
I’d be interested to hear the answer to this, but don’t really want to see it. Wouldn’t it look terrible?
looofooo0 1y ago
https://gicon-hoehenwindrad.de/ https://gicon-hoehenwindrad.de/ They test-building a 380m wind turbine in such a style now.
- patall 1y ago
  I know it's a test project and one shouldn't be to stoked about a test project, but for the last year I have again and again searched for updates about it. Unfortunately, they keep it (understandably) low. Let alone the story of the 90+ year old engineer that envisioned such a project (and they are only implementing 20% of it) is so awesome. Looking forward to when it finishes and hopefully changes our view on wind power for good!
cluckindan 1y ago
The forces acting on the wind turbine tower are mostly perpendicular, i.e. the wind hitting the blades and the structure. Ideally, the blades have maximum wind resistance (up to a point). The construction crane rarely experiences that kind of wind load, because the truss structure is hollow and allows air to pass through. Ideally, the structure has zero wind resistance (down to a point).
flir 1y ago
UK has moved from open grid style to a cylinder style for electricity pylons. Presumably there's an advantage to it, but I don't know what it is: https://www.nationalgrid.com/national-grid-energise-worlds-first-t-pylons https://www.nationalgrid.com/national-grid-energise-worlds-f...
- scrlk 1y ago
  Ostensibly for aesthetics. However, the new T-pylon design has been discontinued for cost reasons, and there were complaints about noise in high winds: https://eandt.theiet.org/2025/01/06/national-grid-abandons-costly-t-pylon-redesign-report-claims https://eandt.theiet.org/2025/01/06/national-grid-abandons-c...
- potato3732842 1y ago
  I can't speak to the UK but in the US things like electrical towers and highway signs mostly go to tubular construction for labor cost reasons. Tube gets manufactured in a facility specializing in doing it in a low labor way (rolling or whatever). Flanges get welded on, they get slapped on cribbing and trucked to you and then assembled with minimal labor. Contrast with the lattice. Cheaper material inputs, a whole bunch of cheap channel with holes punched as needed, but all that punching, and then all that bolting, takes way more labor, a lot of it can be done cheaply, but it adds up, and when it does get to site there's more pieces to pick and connect, etc. Basically the more expensive material saves you quite a bit of human labor at each step. Same reason huge rolled steel and welded tubes displaced riveted construction.
wizardOfScience 1y ago
A wind turbine tower is essentially a cantilevered beam resisting the bending moment from lateral wind loads. The loads can come from any direction. Bending induces stresses in any beam that increase with distance from the centre. A thin walled hollow tube is the most material efficient design theoretically as it concentrates the load bearing materials along the perimeter of the beam. Any deviation from this incurs material that is not fully utilised.
- Onavo 1y ago
  This is what I come to HN for, kudos
- adwn 1y ago
  Your explanation raises the follow-up question, which svantana already hinted at: Why don't construction cranes use hollow tubes instead of their typical truss structures?
  - IsTom 1y ago
    Certainly makes them easier to disassemble and move elsewhere.
    - dguest 1y ago
      Yeah it's pretty essential that construction equipment be pretty easy to construct and deconstruct. There are some videos [1] which are worth checking out. [1]: https://www.youtube.com/watch?v=vx5Qt7_ECEE https://www.youtube.com/watch?v=vx5Qt7_ECEE
  - wizardOfScience 1y ago
    The crane manufacturing business case is not driven by material efficiency to the same degree. It is a tool that needs to be reliable and have performance in operations. Limit the need for man hours through ease of use etc. It should also be able to take many assembly/disassembly cycles. Thus does the amount of material not matter as much in a crane. For wind turbine towers the material cost can be >>50% of the installed cost.
mkj 1y ago
Nabrawind have something like that. It's still a column at the top for blade clearance, but the rest is a grid structure so it doesn't need huge external cranes. https://www.nabrawind.com/our-solutions/nabralift/ https://www.nabrawind.com/our-solutions/nabralift/
impossiblefork 1y ago
No, the optimal shape is a thin dense shell with a stiff low-density interior. Optimization only leads to trusses if you constrain the design to have no low-density elements. In practice this leads to things like a thing CFRP surface wrapped around balsa or stiff foam.
metalman 1y ago
It is likely that ,while a truss would be lighter and stronger, to counteract the forces encountered by a turbine it would also require a cross section so large, as to interfere with the blade travel, rendering the proposal, impossible. There are small wind turbines useing truss style towers, but they all have a "stub" tower on top, and they are under 10kw......10-15'blades. the wooden tower under discussion, is also "small" by todays standards, and unlike steel towers that can be made by any half respecting medium sized fabricator, will require a specialised industrial facility that cant make anything else usefull, and so the one that is doing this, is funded at great expense from government grant funding. kinda cool,kinda cringe

I never understood why wind turbine towers are built as hollow, tapered cylinders. Isn't the best mass-to-strength ratio acheived with truss/grid type structures, like in construction cranes?

lostlogin 1y ago

I’d be interested to hear the answer to this, but don’t really want to see it. Wouldn’t it look terrible?

looofooo0 1y ago

https://gicon-hoehenwindrad.de/ https://gicon-hoehenwindrad.de/ They test-building a 380m wind turbine in such a style now.

patall 1y ago
I know it's a test project and one shouldn't be to stoked about a test project, but for the last year I have again and again searched for updates about it. Unfortunately, they keep it (understandably) low. Let alone the story of the 90+ year old engineer that envisioned such a project (and they are only implementing 20% of it) is so awesome. Looking forward to when it finishes and hopefully changes our view on wind power for good!

cluckindan 1y ago

The forces acting on the wind turbine tower are mostly perpendicular, i.e. the wind hitting the blades and the structure. Ideally, the blades have maximum wind resistance (up to a point). The construction crane rarely experiences that kind of wind load, because the truss structure is hollow and allows air to pass through. Ideally, the structure has zero wind resistance (down to a point).

flir 1y ago

UK has moved from open grid style to a cylinder style for electricity pylons. Presumably there's an advantage to it, but I don't know what it is: https://www.nationalgrid.com/national-grid-energise-worlds-first-t-pylons https://www.nationalgrid.com/national-grid-energise-worlds-f...

scrlk 1y ago
Ostensibly for aesthetics. However, the new T-pylon design has been discontinued for cost reasons, and there were complaints about noise in high winds: https://eandt.theiet.org/2025/01/06/national-grid-abandons-costly-t-pylon-redesign-report-claims https://eandt.theiet.org/2025/01/06/national-grid-abandons-c...
potato3732842 1y ago
I can't speak to the UK but in the US things like electrical towers and highway signs mostly go to tubular construction for labor cost reasons. Tube gets manufactured in a facility specializing in doing it in a low labor way (rolling or whatever). Flanges get welded on, they get slapped on cribbing and trucked to you and then assembled with minimal labor. Contrast with the lattice. Cheaper material inputs, a whole bunch of cheap channel with holes punched as needed, but all that punching, and then all that bolting, takes way more labor, a lot of it can be done cheaply, but it adds up, and when it does get to site there's more pieces to pick and connect, etc. Basically the more expensive material saves you quite a bit of human labor at each step. Same reason huge rolled steel and welded tubes displaced riveted construction.

wizardOfScience 1y ago

A wind turbine tower is essentially a cantilevered beam resisting the bending moment from lateral wind loads. The loads can come from any direction. Bending induces stresses in any beam that increase with distance from the centre. A thin walled hollow tube is the most material efficient design theoretically as it concentrates the load bearing materials along the perimeter of the beam. Any deviation from this incurs material that is not fully utilised.

Onavo 1y ago
This is what I come to HN for, kudos
adwn 1y ago
Your explanation raises the follow-up question, which svantana already hinted at: Why don't construction cranes use hollow tubes instead of their typical truss structures?
- IsTom 1y ago
  Certainly makes them easier to disassemble and move elsewhere.
  - dguest 1y ago
    Yeah it's pretty essential that construction equipment be pretty easy to construct and deconstruct. There are some videos [1] which are worth checking out. [1]: https://www.youtube.com/watch?v=vx5Qt7_ECEE https://www.youtube.com/watch?v=vx5Qt7_ECEE
- wizardOfScience 1y ago
  The crane manufacturing business case is not driven by material efficiency to the same degree. It is a tool that needs to be reliable and have performance in operations. Limit the need for man hours through ease of use etc. It should also be able to take many assembly/disassembly cycles. Thus does the amount of material not matter as much in a crane. For wind turbine towers the material cost can be >>50% of the installed cost.

mkj 1y ago

Nabrawind have something like that. It's still a column at the top for blade clearance, but the rest is a grid structure so it doesn't need huge external cranes. https://www.nabrawind.com/our-solutions/nabralift/ https://www.nabrawind.com/our-solutions/nabralift/

impossiblefork 1y ago

No, the optimal shape is a thin dense shell with a stiff low-density interior. Optimization only leads to trusses if you constrain the design to have no low-density elements. In practice this leads to things like a thing CFRP surface wrapped around balsa or stiff foam.

metalman 1y ago

It is likely that ,while a truss would be lighter and stronger, to counteract the forces encountered by a turbine it would also require a cross section so large, as to interfere with the blade travel, rendering the proposal, impossible. There are small wind turbines useing truss style towers, but they all have a "stub" tower on top, and they are under 10kw......10-15'blades. the wooden tower under discussion, is also "small" by todays standards, and unlike steel towers that can be made by any half respecting medium sized fabricator, will require a specialised industrial facility that cant make anything else usefull, and so the one that is doing this, is funded at great expense from government grant funding. kinda cool,kinda cringe